Surgery of the urogenital system (Proceedings)

I. Kidneys

Anatomy

The kidneys of the dog are paired, reddish brown, and bean-shaped. They measure 5-9 cm in length, 4-5 cm in width and weigh approximately 25-60 gm (this represents 0.67% of body weight). The cranial pole of the right kidney is embedded in the renal fossa of the caudate lobe of the liver at the level of the 13th rib and is fixed to the Eivtr by the hepatorenal ligament. The left kidney is mobile and lies about 5 cm caudal to the 13th rib.

The kidneys are covered by a strong, thin, fibrous capsule and are surrounded in their sublumbar position by peritoneum and renal fascia variably infiltrated with fat. The medial border of the kidney is indented by an ova sinus (hilus) which opens into the renal pelvis. At the hilus the lymphatics, nerves, ureter, artery, and vein enter or leave the organ.

The renal artery of the dog always originates from the aorta and enters the kidney at the hilus, the right kidney usually has one artery, whereas the left kidney can have paired arteries in about 13% of the population. Paired arteries are variably located in relation to the renal vein. Most commonly, however, one lies dorsal and cranial to the vein, whereas, the other lies dorsal and caudal to it. The single renal artery usually lies dorsal and caudal to the vein, with its trunk dividing variably along its length into two primary branches.

The anatomy of the feline kidneys is similar to the dog's except that the feline kidneys are more spherical in shape, usually smaller (0.70% of body weight) more loosely attached in their sublumbar region, and are grayish in color. The renal artery is usually single and originates from the aorta, Approximately 27% of feline kidneys have paired renal veins, and 3 or 4 veins are encountered on Occasion,

In both species, the left gonadal vein drains into the left renal vein, while the right gonadal vein drains directly into the caudal vena cava.

The ureters leave the kidneys at the caudal aspect of the hilus coursing retroperitoneal and entering the bladder through the two layers of peritoneum that form the lateral ligaments of the bladder.

Pathophysiology

The functional reserve of the kidneys is large (approximately 90%) and much damage may occur before functional impairment is evident.

The anatomic interdependence of the component parts of the kidney (glomerulus, tubules, blood vessels and interstitium) implies that damage to one will subsequently affect the others. For example, disease primarily in the blood vessels must inevitably affect all the structures dependent on blood supply. Severe glomerular damage will impair the flow through the entire peritubular vascular system. Thus, there is a tendency for all forms of renal disease ultimately to destroy all four components of the kidney, culminating in the "end-stage renal failure".

Because of the large functional reserve, renal disease may not become manifest until after there has already been extensive damage.

The kidney reacts to tissue injuries in ways similar to all other tissues of the body. Acute inflammation evokes exudation, white cell accumulation, and tissue damage, while chronic, long standing inflammation produces scarring and permanent destruction of elements.

Surgical Procedures of the Kidney

Nephrectomy - indications include urethral or renal trauma affecting the majority of renal parenchyma, renal and perirenal cysts, renal and perirenal abscesses, extensive unilateral hydronephrosis resulting from an uncorrectable ureteral obstruction, Dioctophyma renal infestation, neoplasia, and advanced unilateral pylonepliritis.

Nephrectomy is rarely performed when architecture and blood supply of the kidney are normal. The procedure being the kidneys are exposed through a ventral midline abdominal incision from the xiphoid through the umbilicus, the right kidney is further exposed by utilizing the mesoduodenum as a retractor; the left kidney, by using the mesentery of the descending colon. The kidney is then freed by inserting a finger through the peritoneum and perirenal fascia at either the cranial or caudal pole and stripping these attachments from the renal capsule. Next, perirenal fat is reflected from the ventromedial surface of the renal hilus in order to expose the renal vein and ureter. By dividing the ureter between 2-O PDS ligatures, it is further mobilized to permit ligation as close as possible to the urinary bladder.The kidney is lifted from its bed and retracted medially to expose perirenal fat on the dorsolateral surface of the renal hilus. Reflection of this fat will expose the renal artery, which, with the renal vein, is separated and independently ligated with 1-0 PDS suture material, Care must be taken to preserve the gonadal vein of the left kidney while this kidney is being removed. A separate transfixation ligature of 3-0 PDS suture material is passed through the lumen of the renal artery and vein distal to the first ligature.

The intestines are returned to normal position, the greater omentum is replaced over the small intestine, and the abdomen is closed in a routine manner.

Post-operative considerations - no special aftercare is necessary unless a patient is in shock or is uremic. If infection is present, antibiotics are indicated preferably selected on the basis of culture and antibiotic sensitivity.

Nephrotomy (nephrolithotomy) - indications include removal of renoliths and early Dioctophyna renale infestation. Usually, the kidneys associated with renal calculi are diffusely infected, and therefore appropriate antibiotic therapy is mandatory pre-surgically. It should be noted if severe pyloneptiritis is present and the other kidney is normal, nephrectomy is preferred. Preoperative urinalysis should be performed and appropriate antibiotics administered within 24 hours prior to surgery.

Exposure of the kidney(s) and mobilization of the renal artery and vein are as previously described. Calculi may be removed by the incision of the renal parenchyma from the greater curvature. An assistant holds the exposed kidney cupped in the palm of his hand and occludes the renal vessels by digital pressure; vascular forceps may be used for this occlusion, but the ureter should not be included in the clamp.

An alternate procedure utilizes silk suture (1-0) passed around the renal artery and through a 2 cm length of rubber tubing and utilized to occlude the artery, and the procedure repeated on the renal vein.

A single incision to the depth of the renal pelvis is preferred to repeated incisions, The incision should provide adequate exposure of the pelvis without bisection of the kidney. The edges of the incision are gently spread, and remaining blood is irrigated from the kidney to permit inspection of the pelvis. The renal calculi are carefully removed with forceps and the renal pelvis is flushed with warm isotonic saline. A culture is then performed from the renal pelvis. (renal calculi often are very friable and will fragment if handled roughly.) A 3-½ French catheter is gently passed down the ureter toward the bladder to check for obstruction, The incision is closed with 3-0 PDS in a simple continuous suture, placed through the capsule and the renal cortex, These sutures should be inserted with a swedged-on. fine diameter, ⅜ circle tape needle; they should include a small amount of renal Cortex with the capsule; and there should be only gentle approximate tension on the sutures. Organ ischemia should not exceed 30 minutes.

The kidney should be returned to its normal position. if hemorrhage is present and cannot be controlled by gauze sponge and pressure. a strip of oxidized regenerated cellulose may be placed over the incision. The abdomen is closed in a routine manner.

Post-operative considerations - high urine volume should be maintained until the animal begins to eat and drink and until the measurements of renal function are essentially normal. Serum electrolytes and acid-base balance should be determined and used as a guide for replacement therapy. Antibiotic treatment is necessary and may be indicated for the rest of the animal's life, depending upon the extent and etiology of infection. Salts should be added to the diet to stimulate increased water consumption and urine output. Low protein diets of high quality are indicated immediately post-op for 2 3 weeks unless the patient has a continued elevated plasma creatinine and plasma urea nitrogen value. Depending on stone analysis, post-operative therapy should begin in order to prevent recurrence of renoliths of metabolic origin.

Percutaneous (Needle) Biopsy of the Kidney needle biopsy is absolutely indicated when the results of biopsy are likely to establish a specific diagnosis, to determine a type of therapy, or to indicate a prognosis, provided the patient can tolerate the procedure without the undue risk of senous complications.

Contraindications include anemia, solitary functional kidney, oliguria or anuria, severe azotemia, hypertension, hydronephiosis, intrarenal infection, renal cysts, tumors or obstructive uropathies, hemorrhagic tendencies, inexperienced clinicians, severe circulatory dysfunction, damaged needle, and an uncooperative patient.

Percutaneous biopsies are often performed regardless of contraindications because the conditions are often undetected or not considered an unacceptable risk.

Biopsy needles used are:

1) Fnaildin modified Vim-Silverman biopsy needle, designed to isolate a plug of tissue without suction, It consists of 3 components: an outer canula, a stylet, and a cutting p1ugs.

2) Metcoff pediatric modification of the Franklin-Silverman needle, is used on Sm: patients. It is a miniature replica of the Franklin modified Silverman needle.

3) Vim Tru-cut biopsy needle, operating on a principle similar to that utilized by Franklin-Silverman biopsy needle, One should always precede biopsy with a clotting survey (platelet count, PT, PTT)+

Preoperative preparations include fasting for 12 hours as recommended. Whole blood clotting time and platelet count are obtained. Electrolyte and acid/base abnormalities should be corrected prior to procedure. fluid and diuretic administration to obtain adequate urine production is recommended. if blind biopsy technique is to be employed, evacuation of colon via enema and immediate pre-op emptying of the bladder should be performed.

Biopsy may be safely performed with local anesthesia of 2% lidocaine infiltration (never exceeding 4.4 mg/kg) following pre-op sedation with morphine and atropine.

Most animals, however, require general anesthesia and this author prefers inhalants. Halothane, or halothane nitrous oxide combinations following induction with ultra short acting barbiturates has found favor. Dogs should be premedicated with atropine (.04 mg/kg) and oxymorphone (.22 mg/kg) while cats respond well to atropine (.04 mg/kg) and acepromazine (.22 mg/kg). Avoidance of renal elimination agents is advocated.

Keyhole technique - the animal is surgically prepared over the kidney to be biopsied. (The right kidney of the dog is usually chosen because its anatomic position is more constant than that of the left kidney.) An oblique para-lumbar skin incision is made, large enough to accommodate an index finger over the caudal pole of the kidney.

The incision should be made caudal to the last rib and just below the ventral border of the lumbar muscles, (Avoid the intercostal artery caudal to the last rib.) The long axis of the incision should be located approximately equidistant between the last rib and the ventral border of the lumbar muscle; the underlying subcutaneous tissue, muscle and peritoneum are then bluntly dissected with scissors; the index finger is inserted through the incision and the peritoneal cavity, and the kidney is palpated.

It may be necessary to introduce the biopsy needle through a separate site in the body wall; in that case, a tiny skin incision just large enough to accommodate the biopsy needle is made adjacent to the keyhole incision. The needle is guided into the peritoneal cavity and then to the kidney by the index finger. In this procedure, it is absolutely necessary that the kidney be immobilized by displacing it against the body wall with the index finger.

The long axis of the needle should be directed away from the renal artery, vein and pelvis, whereas the tip of the needle should be in contact with the renal capsule, the needle being positioned in such a way that the cutting prongs will not pass through the renal capsule twice.

The cutting prongs must be thrust into the renal parenchyrna. An assistant should grasp the hub of the cutting prongs and firmly hold them in exact position, the outer cannula is then advanced over the blades, As the cannula is being advanced, its continuous, alternating rotation (5 degrees clockwise and then 5 degrees counter-clockwise) will help prevent over-penetration of the renal parenchyma; but counter traction extended on the cutting prongs must be avoided, Following these procedures, the outer cannula should be advanced just beyond the landmark scratched in the shaft of the cutting prongs. One should repeat this procedure 2 or 3 times to insure a representative biopsy.

Prior to closure of the surgical wound, one should examine the area for presence of excessive hemorrhage. In the event of significant bleeding, digital pressure applied directly over the biopsy site is often sufficient to enhance clotting or surgical gelfoam may be placed on the renal capsule over the biopsy site.

Blind percutaneous technique - used primarily for cats. Surgically prepare the area over the biopsy site and induce a local or general anesthesia. (Use ketamine with caution, if at all, in cats with renal failure since the drug is excreted in urine in active form.) Next, localize and immobilize the kidney to be biopsied by digital palpation through the abdomen. Then make a small skin incision over the proposed biopsy site to facilitate entry of the biopsy needle, Proceed as described for the keyhole technique.

For patients that arc debilitated or have infectious processes of the kidney, antibiotics are initiated, the most effective method of preventing the formation of blood clots in the excretory pathways (especially in cats) has been the parenteral administration of a quantity of lactated ringers solution sufficient to initiate a mild diuresis prior, during and/or immediately following renal biopsy. The most serious complication following renal biopsy in the dog is severe hemorrhage - usually a result of faulty technique.

II. Ureters

Anatomy

The ureter is a fibromuscular tube, surrounded by a sheath composed of transverse fascia, which enters the bladder obliquely on the dorsolateral surface in its trigone and is retroperitoneal throughout its course. Its oblique course is partially responsible for preventing reflux of urine up the ureter during normal bladder function. Its blood supply is from the renal artery cranially (cranial ureteral artery) and from the vesicular artery caudally (caudal ureteral artery). Each ureter is innervated by autonomic nerves through the cellac and pelvic plexuses.

Pathopitysiology

The contractile system of the ureter is complex. The filling of the renal pelvis initiates a peristaltic contraction that begins at the pelvis and spreads down the ureter, forcing urine toward the bladder.

The ureter is capable of great regenerative powers if defects, either traumatic or surgical, are in a longitudinal direction, but it withstands cross-sectioning poorly. No matter how long the defect, it will heal if it has been made in a longitudinal direction and if the strip of ureter contains a full thickness of ureteral tissue. But cross-sectioning often results in stricture, making anastomosis an impractical technique. Similarly, the ureter responds poorly to overstretching and so should be under no tension. Finally, although the ureter can be stripped of much of its blood supply without problems, it does not tolerate an excessive number of sutures; for these may strangulate its blood supply.

Ureteritis almost invariably develops secondarily to infection elsewhere in the body, particularly in the kidneys (pylonepritis) or bladder (acute or chronic cystitis). The morphologic changes are usually quite minimal and consist of hyperplasia and granularity of the ureteral mucosa. Most of the inflammatory changes are confined to the sub-mucosal connective tissue.

The overlying epithelium is ulcerated only occasionally and in acute conditions.

Surgery of the Ureter

Repair of longitudinal defects - to expose the right ureter, the mesoduodenum can be used to retract the remainder of the abdominial contents from the surgical field. To expose the left ureter, the descending colon and mesocolon can be used for retraction. Care should be taken to protect the pancreas. With ureterolithiasis, a longitudinal incision should be made over the calculus and the calculus removed with forceps. The ureter should be flushed with saline solution through a small catheter or polyethylene tube. The renal pelvis and bladder should be palpated for detection of other calculi. The longitudinal defect is sutured with interrupted 5-0 or 6-0 PDS sutures through the muscular coat into the mucosa. The edges of the incision are brought into loose apposition; as little narrowing of the lumen as possible is ideal. The ureteral incision should be covered with adjacent adipose tissue, since this allows free movement of peristalsis and aids in prevention of periureteral fibrosis, The incision site should be drained with penrose drains to prevent accumulation of urine. In the event of a longitudinal incision or defect, no stent is necessary, the ureteral sheath provides stenting and also prevents periureteral adhesions. when there is a severe defect caused by trauma to the periureteral sheath, a stent is indicated. A No, 4 French catheter or a small polyethylene tube is passed retrograde from the bladder to the kidney and from the bladder Out the urethra. As small a stent as possible should be used; and it can be sutured in place at the vulva or sheath, It should remain indwelling for a minimum of 2 weeks. a stent is necessary for regeneration of a normal-sized lumen and for proper drainage of the operative site. No sutures are needed. With severe trauma to the ureter, a nephroureterectorny may be indicated if the ureter cannot be re-implanted into the bladder.

Transplantation of the ureter - the bladder is exteriorized, and affected ureter(s) are identified, The end of the ureter to be transplanted is isolated, and 2 through and through stay sutures of 3-0 are placed close to the end to prevent excessive handling. The distal end of the ureter is traced to the bladder, excised and the bladder defect is closed in a simple interrupted pattern with 3-0 PDS. A stay suture should be placed on the apex of the bladder, which is incised ventrally from the apex to an area opposite the trigone. Stay sutures are placed on the edges of the incised bladder wall.

A small incision (1 cm) is made dorsally through the serosa. From this incision a 2-3 cm subserosal tunnel is made with curved mosquito forceps. This tunnel should open near the normal ureteral opening into the mucosa of the trigone. It should not be made dlrectly under the serosa, but should include some of the outer longitudinal layer of the muscle wall of the bladder to prevent the serosa from tearing. The purpose of this tunnel is to act as a valve when the bladder fills, preventing ureteral reflux of urine.

After the tunnel has been made the desired length, the tops of the mosquito forceps are directed through the muscle layers to the mucosa. The mucosa is incised over the tips of the forceps through the ventral incision in the bladder. The curved forceps are introduced into the mucosal incision, passed through the tunnel, and brought out at the serosa. The bladder is then replaced in its normal position.

The stay sutures in the ureter are grasped in the forceps and pulled through the subserosal tunnel. With gentle traction on the sutures, the ureter is pulled through the tunnel into the lumen of the bladder. The end of the ureter that contained the stay sutures is excised, The ureter is spatulated 0.5 cm on the ventral aspect of its opening to enlarge the lumen. The ureteral mucosa is sutured to the bladder mucosa with 3 interrupted 4-0 PDS sutures. Tension on the sutures should be minimal

Post-operative considerations - Continue to monitor urinary output and fluid intake, Patient should be kept on urinary antibiotics at least one month following discharge- At 4-6 weeks post-OP, an IVP and contrast cystogram should be performed to check ureteral patency and check for ureteral reflux or transplanted ureters. At 4-6 weeks post-op, the ureter should be normal in size and ureteral reflux should be absent.

III. Urinary Bladder

Anatomy

There are three layers of muscles in. the wall of the urinary bladder: outer and inner longitudinal layers and a relatively thick middle circular layer. The muscle fibers all take on an oblique or circular appearance at the urethral-bladder junction forming a sphincter. The mucosa is made up of transitional epithelium; a loose submucosa lies between the mucosa and muscular layer.

The ventral surface of the bladder is separated from the abdominal wall, just cranial to the pubis, by visceral and parietal layers of peritonenm. The greater omentum frequently occupies the space between peritoneal layers. Dorsally, the bladder is in contact with the small intestine and, in the female, with the descending colon, cranial to the divergence of the uterine horns from the body of the uterus.

In the male, the deferent ducts are dorsal to the neck of the bladder, whereas in the female the cervix and body of the uterus are in contact with the dorsal surface of the bladder. When empty, the bladder lies entirely, or almost entirely, within the pelvic cavity. The space on each side of the bladder is occupied by the uterus and small intestine.

The ventral ligament of the bladder is reflected from the ventral surface of the bladder to the pelvic symphysis and the mid-ventral line of the abdominal wall as far cranially as the umbilicus. It is median in position and triangular in shape. The lateral ligaments of the bladder connect the lateral surfaces of the bladder to the lateral pelvic walls. They are also triangular in shape. In the female they blend with the broad ligament of the uterus as well as the lateral pelvic wall, The ureter and round ligament cross at nearly right angles to each other at the junction of the broad and lateral ligaments.

The bladder receives its blood supply through the cranial vesical artery, a branch of the umbilical artery, and through the caudal vesical artery, a branch of the urogenital artery (the termination of the visceral branch of the internal iliac artery). The plexus of veins on the urinary bladder drains primarily into the internal pudendal veins. The bladder receives innervation from the pudendal nerve (its somatic innervation), and from the pelvic nerve (its parasympathetic innervation).

Pathophysiology

Cystitis is the most common form of lesion in the urinary bladder, Infection and inflammation are thought to play a significant role in the etiology of phosphate uroliths, which are associated with an alkaline urine and make up 60-90% of all uroliths in dogs. The first alteration in cystitis is hyperemia of the mucosa, Later, the hyperemia may be transformed to focal or diffuse hemorrhagic discolorations associated with the precipitation grey-white to yellow suppurative exudate. As the inflammatory reaction progresses in severity, the normal velvety mucosa is replaced by friable, hemorrhagic, granular surface with many shallow, focal ulcers filled with exudate. Progression of infection may give rise to sloughing and ulceration of large areas of mucosa, In time, chronic cystitis occurs where the mucosa is more edematous, and the inflammatory reaction tends to cause more extreme heaping up of the epithelium of the formation of a red, friable , granular and sometimes ulcerated surface. There is fibrous thickening and inelasticity of

the bladder wall.

Knowledge of the composition of uroliths is of clinical significance because prognosis and choice of prophylactic procedures are dependent upon composition. 60-90% of all uroliths in dogs are composed of phosphates (phosphate uroliths). They are radio- opaque and composed of varying amounts of Mg++, NH4+ and Ca++ together with phosphate. They are associated with an alkaline urine and therefore usually infectious. Urate urotiths comprise about 10% of all uroliths in dogs. They are radiolucent and are composed of NH4+ urate. There is a hereditary trait of Dalmation dogs to excrete large quantities of uric acid in urine (a purine metabolic byproduct). They can be associated with other breeds also. Cystine uroliths comprise about 5% of all uroliths in dogs. They are radiolucent and composed of the anino acid cystine. They are found in many breeds and reported exclusively in male dogs. It is thought that there may he a genetic defect of the resorption of cystine from the renal tubules, Oxalate uroliths comprise about 10% of all uroliths in dogs. They are radio-opaque and are comprised of calcium oxalate. They are more frequently found in the urethra of the male dog, as are cystine and urate uroliths.

Surgery of the Bladder

Cystotomy - a caudal midline abdominal skin incision is made, Once the bladder is exteriorized, two stay sutures of 2-0 or 3-0 silk are placed at the apex of the bladder to prevent withdrawal back into the abdomen. The bladder is isolated and packed off with towels or laparotomy pads to prevent abdominal contamination, The bladder should be reflected caudally so that the incision can be made on the dorsal surface. A second stay suture is placed at the base of the bladder A small incision should be made in a non-vascular area, as close to the middle as possible, so that remaining urine can be removed by suction, The bladder incision is extended with care between the two stay sutures. Calculi should be removed carefully and preserved for lab analysis and culture, and a direct swab of the bladder should be taken for culture. A sterile urinary catheter is passed from the bladder to the urethra and flushed with sterile saline solution to make certain that no calculi remain in the urethra. Numerous flushings of the bladder, penis or urethral papilla in the vagina are necessary A full thickness bladder wall biopsy is taken from the incision for histopathologic examination and culture before closure, The bladder can be closed in a 2 layer continuous suture pattern with 2-0 or 3-0 PDS. The first layer is placed in a continuous pattern and the second is a Cashing or Lembert. The stay sutures are removed and the bladder is returned to the abdominal cavity in a normal position. The abdomen is closed in routine manner. An alternative method in closing the bladder is the Bell (baseball) suture pattern oversewn with a Lembert pattern.

Post-operative considerations - treatment of calculi and cystitis is a long term affair. For 4-6 weeks, change every 10-14 days, and reculture 7 days after last antibiotic. Antibiotic sensitivity should be performed on the culture to determine the proper regimen for the dog. Calculi analysis should he performed on the culture to determine the proper regimen for the dog Calculi analysis should be performed and appropriate prophylaxis induced, For phosphate calculi, infections must be eliminated, PD/PU should be induced with oral NaCl given at 1-10 grams of salt per day in divided dosages. Start on urinary acidifiers if phosphate dictates until infection has been eliminated. For urate calculi induce PD/PU with salt, alkalinize the urine with administration of NaHCO3 and NaCl. Eliminate any infection if present and do not use urinary acidifiers since urates are less soluble at a low pH. Zyloprim is given for prevention. For cystine calculi induce PD/PU, alkalinize the urine by administration of NaHCO3 and NaCI (keep urine pH above 7+15). Eliminate any infection if present and consider use of D-penicillamine for recurrent urolith formation; it combines with cysteine and decreases urinary excretion of less soluble cysteine. Do not use urinary acidifiers. For oxalate calculi induce PD/PU and eliminate urinary tract infections.

IV. Urethra

Anatomy

The entire urethra is lined with transitional epitheliurn with the exception of a small amount near the tip of the penis or urethral tubercle. Urethral muscle is composed of an inner longitudinal layer of smooth muscle and an outer transverse layer of skeletal muscle that are separated dorsally by a longitudinal raphe.

Blood supplies are mainly from the urogenital and/or internal pudendal arteries depending on whether the dog is a male or female. Venous drainage is primarily through the internal pudendal vein, Autonomic nerves from the pelvic plexus supply the smooth muscle of the urethra. Voluntary control of muscle is mediated by the pudendal nerve.

Pathophysiology

Urethral reaction to foreign objects is dependent on many variables; e.g., individual patient response, length of time the foreign objects are lodged, the type of foreign object (calculi, catheter, etc.), and absence or presence of secondary infection. In humans, urethras show some reaction after 2-3 days of indwelling catheter. This reaction is superficial and does not clearly indicate that the degree of submucosal reaction is probably important in breaking down body defense mechanisms to infections as well as in causing scarring of the urethra after the foreign body has been removed.

Surgery of the Urethra

Urethral prolapse - the cranial prepuce and surrounding abdomen are clipped and scrubbed. The preputial diverticulum and penis are irrigated with an antiseptic solution prior to scrubbing and draping. When the prolapse is small and not grossly engorged with blood, a conservative repair is indicated. The penis is extended from the sheath and grasped between the thumb and forefingers. A well lubricated catheter of the largest diameter that can easily be inserted is passed up the urethra as an attempt is made to reduce the prolapse. If the prolapse easily reduces, the catheter is inserted a short distance into the urethra and a purse-string suture of 3-0 or 4-0 nylon material is placed around the end of the penis The catheter is sutured to the prepuce to maintain its position in the urethra and bladder for 5-7 days. When the prolapse is severe, amputation of the prolapsed segment is preferred. Again, a well-lubricated catheter is placed in the urethra. To prevent the inner mucosa from retracting, four stay sutures are placed equidistant around the tip of the penis and through the urethral mucosa, The prolapse is excised over the catheter as close to the tip of the penis as possible. Simple interrupted sutures of 4-0 or 5-0 PDS are paced around the tip of the penis approximately 0.25 to 0.5 cm apart, uniting the urethral mucosa to the cranial tip of the penis. The catheter is sutured to the prepuce to maintain its position for 3-4 days.

Post-operative considerations - a urinary antibiotic e.g. chloramphenicol or nitrofurantoin is indicated for treatment of any infection. Antispasmodics and/or tranquilizers may be beneficial. Elizabethan collars are useful in preventing catheter removal and licking at the operative site.

Urethrostomies - creation of a new and permanent urethral orifice are performed as one of three types in the male dog, prepubic, scrotal, and perineal. The perineal region is by far the least desirable because of urine scalding of the perineal skin and scrotum. It is also more difficult to suture deep urethra to the skin, if castration is acceptable, scrotal urethrostomy is preferred. if castration cannot be per-formed, a prepubic urethrostomy is the alternative. The indications for this are recurrent stone formation untreatable or unresponsive to medical management, urethral strictures, and patients where medical management might be harmful.

Prepubic urethrostomy - the caudal ventral abdomen and prepuce are clipped, scrubbed and prepared for surgery. A well lubricated urethral catheter is inserted into the penis to the point of obstruction, A 2-3 cm ventral midline incision is wade in the prepuce over the obstructed site, just caudal to the Os penis, and 1-2cm cranial to the cranial margin of the scrotum. The penis is grasped between the surgeon's thumb and forefingers to facilitate dissection to the urethra. The subcutaneous tissue is sharply incised to the retractor penis muscle as near the midline as possible. The retractor penis muscle is identified, isolated, and retracted laterally. At this point the ventral portion of the urethra is visible, surrounded completely by corpus cavernous urethra, An incision is made into the ventral urethral lumen over the calculi or catheter and extended 1-1.5 cm in length. The calculi are removed or retrograded into the bladder as the catheter is advanced. After urethral irrigation, the urethral mucosa is sutured in a simple interrupted pattern through the edge of the incised urethral mucosa, corpus cavernous urethra and skin. The urethrostomy opening should be approximately 1.5-2cm long. One suture should be at the caudal aspect of the incision to create a rounded opening, this will help prevent the skin from growing over the urethrostomy opening.

Scrotal urethrostomy - this surgery relieves strictures of the urethra and allows calculi to pass out and not lodge at the Os penis. The scrotum and surrounding area are clipped, scrubbed and draped. An elliptical skin incision is made around the circumference of the scrotum at its base. The scrotal skin is removed and a routine castration performed. The retractor penis muscle is exposed and dissected from the corpus spongiosum penis and retracted laterally. The ventral portion of the urethra is exposed and appears as a white glistening band of tissue between two bands of cavernus tissue. The urethra is incised for 3-4 cm from its ventral-most portion to the dorsal curve (around the ischial arch). Two stay sutures are placed in the lateral urethral edges. Suturing should begin with the caudal urethral incision to insure an adequate round opening of the urethra, 4 Corner sutures at 45 degree angles are placed. The lateral skin edges are sutured to the urethra with (4-0 or 5-0) PDS suture material in a simple interrupted pattern. Undue tension on the sutures should be avoided and a cosmetic closure obtained.

Postoperative care – (following calculi analysis) culture and sensitivity, prolonged therapy as described above should be instituted.

Perineal urethrostorny - not advocated in the dog due to possible post-operative complications; i.e. urine burns of the skin. A urethral catheter is inserted into the urethra as far as possible; the patient is placed in a perineal position with the tail secured over the back. The perineal area is clipped, scrubbed, and draped after a purse string suture is placed in the anus. A skin incision is made on the midline approximately 2-3 cm dorsal to the scrotum.

The subcutaneous tissue over the urethra, which lies deep on a midline surrounded by the bulbo cavernous muscle, is incised, The urethra can be identified by palpation of the previously incised urethral catheter. The urethra and surrounding cavernous tissue are moved to the incision by gentle manipulation and help with Allis forceps or stay sutures. The fibers of the bulbo cavernous muscle are separated longitudinally over the urethra and the urethra incised over the catheter. Sutures of simple interrupted 4-0 PDS are placed in the urethral mucosa and skin edges to create the urethrostomy opening.

Post-operative considerations - if calculi are flushed into the bladder) a cystotomy is indicated, An Elizabethan collar should. be placed on the animal for at least three days. Urinary antibiotics are administered for 30 days post-operative. if the procedure is improperly performed, urine may extravate into surrounding tissue and create severe edema and inflammation Hemorrhage up to 10 days post-surgery is common.

Obstruction of the distal urinary tract in male cats is common. Stabilization of the patient with restoration of normal renal function should be attempted before surgical intervention. Should renal function be severely compromised due to prolonged obstruction, prognosis is guarded at best.

Perineal Urethrostomies in the cat - the hair of the perineum and external genitalia is clipped and the area scrubbed. A purse- string suture is placed in the anus to eliminate fecal contamination of the surgical field, The patient is placed in the ventral recumbent position with the perineum elevated approximately 30 degrees. The tail is extended over the dorsal midline and immobilized, An open-ended tom cat catheter is positioned. An elliptical incision is made to incorporate the scrotum and prepuce. The prepuce and scrotum are removed, exposing the testes in the intact male or fat in the castrated male. if the cat has not been castrated, castration is performed at this time. The penis is dissected from the surrounding tissue to its pelvic attachment on the ischium. It is reflected dorsally and the ventral dissection is begun. The attachments of ischio-cavernosis is severed, thus freeing the crus of the penis. As the dissection continues, the scissors should be kept parallel to the pelvic floor to avoid lacerating the pelvic urethra. With the penis in dorsal reflection, the ligament of the penis is incised, After this procedure, the penis and pelvic urethra can be freed from the pelvic floor by blunt dissection. The penis is reflected ventrally and the loose areolar tissue on the dorsal aspect of the penis is excised to expose the retractor penis muscles, which lie dorsal to the penile urethra. The bulbocavernosis muscle and bulbourethral glands will also be exposed at the distal pelvic urethra, In the castrated male the bulbourethral glands are atrophied, while in the intact male these glands may be quite large. The retractor penis muscle should be carefully removed from the dorsal aspect of the penis over the penile urethra and blunt finger dissection will help to free the pelvic urethra, The penile urethra is incised longitudinally through the glands penis to the pelvic urethra. This should be done carefully with a scalpel over the indwelling catheter. The incision must extend 1 cm into the pelvic urethra (cranial to the bulbourethral glands) which has a larger diameter than the penile urethra. The pelvic and penile urethra mucosa are sutured to the perineal skin with 4-0 PDS, The distal penis is amputated and the remaining penile urethral mucosa is sutured to the skin. The bladder should be expressed to demonstrate patency of the urethrostomy opening and flushed to clear debris that may be present.

Post-operative considerations - remove the purse string suture from the anus; remove sutures in 7-10 days. Do not use litter but rather shredded paper towel or Yesterday's News cat litter so debris does not stick to the surgical incision, Place an Elizabethan collar on the cat.

V. Uterus

Anatomy

The uterus is a hollow muscular organ that consists of a cervix, body and two horns. It is a tubular y-shaped organ which communicates with the oviducts cranially and the vagina caudally. Its size varies considerably, depending on age, size of animal, number of previous pregnancies, and whether the animal is currently pregnant.

The broad ligaments attach the uterus and ovaries to the body wall. The mesometrium is that part of the broad ligament which attaches the uterus to the dorsolateral body wall. It fuses with the lateral ligament of the bladder with attachment to the pelvic wall. The round ligament is apparently a caudal continuation of the suspensory and proper ligaments of the ovary. In most animals, the round ligament, along with the vaginal process, pass through the inguinal vaginal canal and terminates subcutaneously in or near the vulva.

The uterus is made up of three tunics: serosa, a layer of peritoneum that covers the entire uterus. It is continuous with the mesometrium of the broad ligament. The second, the tunica muscularis, consists of a thin, longitudinal outer layer and a thick, circular inner layer of involuntary muscle. Within the circular layer is the vascular layer containing blood vessels, nerves, and circular and oblique muscle fibers, The tunic mucosa (endometrium), the third, is the thickest of the three uterine tunics. It is lined with. low columnar epithelium whose cells are only temporarily ciliated, Simple branched tubular glands are present in the lamina propria. The mucosal surface of the uterus is reddish in color and may either be smooth or contain low longitudinal ridges which obliterate the uterine cavity in the non-pregnant state.

The uterus is supplied by the ovarian and uterine arteries. The uterine artery is a principle branch of the urogenital artery, which arises from the visceral branch of the internal iliac. The uterus receives sympathetic and visceral afferent fibers through the hypogastric plexus and parasympathetic and visceral afferent fibers via the pelvic nerves.

Pathophysiology

The uterus (endometrium) tends to be susceptible to infection and/or pyometritis in the metestral period, especially due to its close anatomical association with the opening of the urinary tract, During metestrus, the circulating levels of progesterone is highest; excessive or prolonged release of progesterone from retained and/or cystic corporea lutea is considered to be a major factor in the pathogenesis of pyometritis. Progesterone acts to stimulate the proliferation of endometrial glands. A pathological sequel to endornetrial proliferation is the development of cystic endometrial hyperplasia. Progesterone also increases the secretory activity of the endometrial glands which results in production and accumulation of large amounts of fluid. It also maintains a functional closure of the cervix and inhibits myometrial contractility, thus preventing adequate drainage of the uterus. Under this influence it is more susceptible to infection. Estrogens produce actions that are physiologically antagonistic to progesterone: they cause cervical relaxation and dilatation, increase strength of contraction of uterine musculature, and promote drainage of uterine contents. They augment the rate of migration of neutrophils into the uterine lumen, increasing the bactericidal environment of the uterus during estrus.

It is thought that genital bacteria gain entry' to the uterus during estrus and are able to proliferate during metestrus under the influence of progesterone.

The most frequently observed hormonally induced pathological change in the canine uterus is cystic endometrial hyperplasia (CEH). CEH is an exaggerated response of the uterus to progestational stimulation during the luteal phase, and is considered to be the initial phase in the development of canine pyometra. The lesions of CEH persist for long periods of time and may be subsequently found during any stage of the estrus cycle. CEH is characterized by a thickened endometrium with many cystic irregular elevations covering the endometreal surface. Variable amounts of clear mucous may be present. The pathological changes seen in various stages of the naturally occurring disease have been classified by Dow into four types:

Type I - an uncomplicated CEH. No clinical signs of systemic disease. Lttle mucoid discharge may be noted only during metestrus. Bacteria may be isolated from the uterus but no inflammatory reaction is present

Type II - characterized by CEH and diffuse plasma cell infiltration. Vaginal discharge is the only consistent clinical sign Lesion usually develops 40-70 days following estrus Bacterial cultures &e often positive, but no histological evidence of acute inflammation is present. Abdominal radiographs reveal an enlarged uterus, but it is usually less than 2 cm in diameter,

Type III - a variable degree of CEH and superimposed acute endometritis. Large numbers of ultra-luminal neutrophils and cellular debris are present Forty percent of these animals have some degree of myometrial involvement. In severe cases, ulceration of the endometrium results in hemorrhage into the uterine lumen. Dogs are clinically ill, with vaginal discharge, occasional vomiting, abdominal distention, and. rarely, diarrhea. Rectal temperature is usually normal.

Type IV - chronic endometritis without CEH. The uterine walls become thickened and small amounts of exudate are present in the uterine lumen. The quantity of pus in the lumen is determined on whether the cervix is opened or closed, With accumulation of large amounts of pus, the endometrium becomes atrophic and the uterine wall may becorne paper thin, The severity of systemic clinical signs varies inversely with the degree of cervical potency.

Renal involvement in dogs with pyometra may be related to pre- renal uremia, primary glomerular disease, tubular disease, or concomitant renal disease. Pre-renal uremia is the inadequate perfusion of normal glomeruli with blood due either to dehydration associated with vomiting, diarrhea, and profound depression resulting in insufficient water intake; or to shock due to toxemia, septicemia and/or surgery. With time, varying degrees of ischemic tubular disease may develop and primary renal failure may occur due to ischemia.

Primary glomerular disease is a membranoproliferative glomerulonephritis caused by immune complexes, characterized by the localization of soluble, circulating antigen-antibodies-complement complexes in the glomerular walls, These have the potential to stimulate injury (e.g. influx of inflammatory cells) by activation of complement and other mediatory of immune damage. The antigen (not yet identified) may originate from the uterus, either as bacterial antigen or antigen from damaged uterine tissue. Also, the possibility that anti-GBM (glomerular basement membrane) may be present in dogs with pyometra has not been entirely excluded. Antibodies formed against some antigenic component of tissue related to material placenta or uterus may cross-react with GBM antigenic determinants.

Tubular disease is an impaired ability of the kidneys to concentrate urine due to 2 factors: first, a decrease in the capacity of the loops of Henle, distal tubules and collecting ducts to reabsorb water, in spite of adequate circulating levels of ADH; and second, a decrease in the concentration of sodium in the renal medulla. This situation is apparently an example of "renal diabetes insipidus". The exact cause is not known, but it may be related to a thickening of the basement membranes at all levels of the nephron, a thickening due either to bacterial endotoxin (especially E. Coli) and/or immune complex disturbance. Although progesterone (associated with pyometra) causes aldosterone inhibiting effects in man and therefore impaired sodium resorption and subsequent natriuresis, this pharmacologic action of progesterone apparently does not occur in dogs.

Concomitant renal disease is indicated by renal calculi, pyelonephritis, and chronic generalized nephritis of undetermined etiology. It has been observed in dogs with pyometra, especially in dogs middle-aged and older

Other body organs, including bone marrow, liver, spleen, adrenal glands and lungs, may be pathologically altered in canine pyometra. The alteration seen most often is a marked increase in the myeloid-erythroid ratio caused by hyperplasia of myeloid elements. A marked leukocytosis (which is frequently immature) produced in response to the inflamed endometrium, occurs in many cases. In severely toxic animals, bone marrow depression may develop. Extra-medullary myelopoiesis may then occur in the liver, spleen, and adrenal glands due to the inability of the bone marrow to keep pace with peripheral demands for neutrophils. Non-specific inflammatory changes may also occur in the liver. Other abnormalities in the spleen may be focal congestion, atrophy of malpighian corpuscles, infarcts and vascular thrombosis. Occasionally one may observe bilateral adrenal cortical necrosis and the development of medullary hemorrhage; also, adrenal cortical collapse may be associated with those animals that do not recover. Pulmonary change are characterized by congestion, leukocytoses and the presence of numerous megakaryocytes.

Surgery of the Uterus

VI. Vagina and Vulva

Anatomy

Vagina - a musculo membraneous dilatable canal extending from the uterus to the vulva. The length of the dorsal vaginal wall is less than that of the ventral walls because of the oblique situation of the cervix, The vaginal walls are made up of an inner mucosal layer, a middle smooth muscle layer, and an external coat of connective tissue and peritoneum (cranially). The mucosa is non-glandular. stratified squamous epithelium. The muscle layer is composed of a very thin, inner layer of longitudinal muscle, a thick circular layer, and a thin outer longitudinal layer. The submucosa contains a rich plexus of blood vessels, The arterial blood is supplied via the vaginal veins drawn into the internal pudendal veins. The vagina is innervated by sympathetic and parasympathetic nerves from the pelvic plexus and by sensory afferent fibers via the pudendal nerve.

The vulva includes the vestibule, clitoris, and labia. The mucosal surface is covered with stratified squamous epithelium. The body of the clitoris consists of fat, elastic connective tissue, and a peripheral tunica albuginea. The glands clitoris, made up of erectile tissue, contains numerous sensory nerve endings The vestibular bulbs are also composed of cavernous tissue. The labia, covered with stratified squamous epithelium, are rich in sebaceous and tabular glands and also contain fat, elastic tissue, and smooth muscle fibers. The external pudendal artery sends branches to the labia; the urogenital artery supplies the vulva via many branches; the clitoris is supplied by branches of the uteral pudendal artery. The sensory afferent nerves to the external genitalia are derived from the pudendal and genital nerves, Motor impulses to the urethral muscle and vestibular and vulvar constrictors also pass through the pudendal nerve, Automatic innervation to the external genitalia is through the hypogastric and pelvic nerves.

Pathaphysiology

During proestrus and estrus the vestibular and vaginal mucosa normally become swollen, thickened, and turgid. Exaggeration of this estrogenic response occasionally leads to development of a transverse mucosal fold on the floor of the vagina just cranial to the external urethral orifice; i.e., hyperplasia of the vaginal floor, It may protrude between the labia as a red, fleshy mess, The condition is seen most often during a bitch's first estrus and seems to occur more often in brachycephalic breeds. Spontaneous regression occurs during metestrum, but recurrence is common at the next estrus. It is vulnerable to trauma ulceration and inflammation, and interferes with mating; and it is esthetically objectionable. Small ones will regress completely about two weeks after ovariohysterectomy; thus, 0.H. is advisable in recurrent cases. Some leimyomas also mimic vaginal hyperplasia.

Vaginal prolapse is rarer than hyperplasia. It also occurs during estrus and appears as a doughnut-shaped eversion of the uterine vaginal circumference protruding from the vulva, As with hyperplasia of the vaginal floor, the external urethral orifice is ventral to the entire mass; but access to the vaginal canal is through the center of the protrusion rather than dorsal to it. Complete vaginal prolapse can also occur during parturition or advanced pregnancy, resulting from excessive straining while the supportive tissues are relaxed. This inverted structure is subject to hemorrhage, infection, and necrosis.

Surgery of the Vagina and Vulva

Episiotomy and Episiostomy - episiotomy indicated for extirpating tumors, easing parturition, correcting or amputating a vaginal prolapse, correcting congenital defects. Episiostomy indicated to correct dyspareunia and facilitate catheterization in experimental dogs. Local, epidural, or general anesthesia can be used. A purse-string suture is placed around the anal opening at the mucodermal junctions. A medial incision is made, extending the dorsal commisure of the vulvar cleft, All structures making up the vestibulovaginal wall are incised. The incision is extended dorsally toward the anal opening until the desired exposure is obtained, being careful not to excise the anal sphincter muscles. After the procedure is completed, the wall is reconstructed, The mucosa is closed with simple interrupted 3-0 PDS sutures. If the wall is excessively thick, it may be necessary to suture the musculature and/or subcutaneous tissue separately with simple continuous 3-0 or 4-0 PDS sutures. The skin should be closed with 3-0 nonabsorbable sutures or staples using a simple interrupted technique. In episiostomy, the mucocutaneous tissue is closed to enlarge the vestibulovaginal opening permanently. A simple interrupted pattern with 3-0 or 4-0 PDS is used to suture the cut edge of the skin to the mucosa,

Post-operative considerations - the patient must be prevented from licking the surgical wound. Sutures can be removed in 7-10 days usually. Poor technique in repair of the incision - i.e.. inaccurate suture placement, excessive suture tension, or use of through-and-through sutures is the principal cause of pain and discomfort following episiotomy. Permanently enlarging the vulvar cleft changes the flora of the vestibule and vagina and predisposes the animal to urinary tract infection.

Episioplasty - a specific procedure used in the treatment of perivulvar pyoderma, a condition which occurs most frequently in obese, usually spayed, bitches. General anesthesia or an epidural is administered, the area is prepared for surgery, and apurse string suture is placed around the anal orifice. A sufficient amount of skin must be excised to prevent unfolding around the vulva; therefore, the skin around the vulva should be picked up so the incision necessary to remove the redundant folds can be approximated. The incision begins lateral to the ventral commissure of the vulva, proceeds dorsally to the junction of the labia and skin around the vulva, and ends on the opposite side, the second incision starts and ends at the same point as the first but extends in a wider arc. The section of skin to be removed should be crescent-shaped and bilaterally symmetrical; it is excised with scissors. Excess subcutaneous fat is removed. Skin closure is facilitated by pulling the margins of the excision together with subcutaneous sutures (3-0 PDS sutures placed in a simple continuous or simple interrupted pattern). The skin is approximated with nonabsorbable sutures or staples placed in a simple interrupted pattern. Some surgeons prefer to use 3-0 mono-filament wire to close the skin to reduce tendencies to tick the skin, Placing the initial skin suture between the skin edges at the dorsal commisure of the vulva and anus, so as to divide the incision equally, is usually helpful in approximating the skin edges accurately.

Post-operative considerations - prevent animal from licking surgical wound and treat remaining pyoderma. Remove the sutures in about 10 days and put the animal on a reducing diet if indicated.

Removal of vaginal hyperplasia - an episiotomy is performed to expose the vaginal lumen, The protrusion is elevated so that the urethra can be catheterized and protected. The mass is amputated by making connecting transverse elliptical incisions through its base. One incision is made on the dorsal surface of the mass (cranial aspect of its base), and the other on its ventral surface cranial to the urethral orifice (caudal surface of the base of the mass). The incisions should be made no deeper than necessary to dissect the mass, Closure is accompanied with a simple continnous, transverse suture of 2-0 PDS. The suturing must begin before the entire mass is removed. This helps prevent the vagina from falling cranially out of reach with resulting excessive bleeding. The catheter is removed and the episiotomy incision is closed, These animals should be spayed to prevent reoccurrence.

Post-operative considerations - if bleeding persists, a vaginal tampon can be left in place for 12 hours following the operation.

Vaginal prolapse - the mass should be manually compressed to reduce edema and reduction is attempted; episiotomy may make the reduction easier, Reduction is maintained by heavy nonabsorbable sutures across the vulvar labia. Protection against recurrence can also be gained by hysteropexy i.e, suturing the uterine body or horns to the abdominal wall via a ventral abdominal incision. If reduction is impossible or inadvisable the protruding tissue must be amputated with catheter in place to identify and protect the urethra. A circumferential incision is made in stages through the vaginal wall. The outer everted mucosa is incised first and the incision is deepened to penetrate all layers of prolapsed vaginal tissue until the inner, noneverted mucosa is reached. Hemostasis should be maintained and the proximal mucosal margins are united with 2-0 PDS horizontal mattress sutures. The incision is extended for another short distance, the exposed segment is sutured, and the process is repeated until the amputation is compete.

Post-operative consideration - remove suture around anal orifice, Prevent the dog from licking the area during the healing process.

VII. Prostate Gland

Anatomy

A musculoglandular body that completely encompasses the proximal portion of the male urethra and the neck of the bladder. It is thin dorsally and thickest ventrally. The prostate normally lies on. the symphysis pelvis, partially separated from it by a double layer of peritoneum; this relationship varies with the degree of distension of the urinary bladder. The two defferent ducts enter the craniodorsal surface of the prostate, lying adjacent to each other, one on either side of the median plane They run caudoventrally through the dorsal part of the gland to open into the urethra by two slits, one on each side of the colliculis seminalis.

The prostate consists of numerous compound tubular glands enclosed in interstitial connective tissue containing smooth muscle fibers. It is covered by a fibromuscular capsule. The prostate is the only secondary sex gland in the dog. Its secretions neutralize the acidity of urine and carry the spernmatazoa through the urethra to the female reproductive tract.

The prostate artery, a branch of the urogenital, supplies the gland. Venous and lymphatic drainage is through the urogenital veins and the external iliac lymph nodes.

Pathophysiology

Prostatic hyperplasia - a common change in dogs from the age of two years. Sixty percent of all dogs greater than six years of age are affected to some degree by prostatic hyperplasia. The exact cause is not known; some believe that it is due to a relative increase in the amount of circulating male hormone, while others believe that middle-aged hyperplasia is an inherent growth characteristic, Histology shows epithelial hypertrophy with, often, small cystic acinar enlargement throughout the gland. Signs are usually those of obstruction of the urinary tract or rectum, Dysuria is likely to occur when the prostate is completely abdominal in position, with the bladder displaced cranially from the brim of the pubis by the enlarged gland, and subsequently pinching the urethra over the brim of the pubis. If the prostate enlarges while in its normal position, it will project upwards into the pelvic cavity and obstruct the passage of feces; the obstruction is accentuated when the dog strains to defecate, Reduction in size of the prostate can generally be achieved by administering small amounts of estrogen or antiandrogenic hormones, but recurrence is likely following cessation of treatment. Squamous metaplasia results from indiscriminate use of estrogens. Sequelae which may result secondarily from prostatic cystic hyperplasia include perineal hernia, hypertrophy of the bladder, cystitis, hydronephrosis and pyelonephitis.

Prostatitis - resulting from either hematogenous origin or from an ascending infection through the urinary tract. There may be numerous small abscesses throughout the gland and pain is obvious when the prostate is palpated. Occasionally large abscesses form and may track along the urethral and bladder wall and rupture either into the bladder or into the peritoneal cavity with fatal consequences. In differentiating this from prostatic hyperplasia, emphasis should be placed on the temperature elevation, the WBC count, pain on palpation, presence of purulent exudate, and possibly the age of the dog. With chronicity of infection, atrophy of the glandular alveoli, induration, and shrinkage of the prostate will sometimes occur, The gland may also be enlarged with the dog showing signs similar to those of prostatic hyperplasia. Recurrent anal irritation and pruritis seen in male dogs may be due in some instances to chronic prostatitis.

Prostatic cysts - may result from blockage and accumulation of prostatic secretion or from the vestigual uterus masculinus at the cranial aspect of the prostate. The presence of a Sertoli cell tumor in the testicle has been associated with the occurrence of prostatic cysts. This may be due to enlargement of the uterus masculinus because of excessive estrogens The cyst may enlarge to the point where signs similar to prostatic hyperplasia are seen. The prostate is invariably abdominal in position in these cases and, because of the degree of enlargement, tenesmus may occur with or without urinary signs. Estrogens are contraindicated in treating prostatic cysts. Prostatic abscesses and tumor (carcinoma) must be ruled out when investigating the causes of prostatic disease.

Surgery of the Prostate Gland

There are a number of different approaches one may take when operating on the prostate gland; 1) perineal, 2) extra peritoneal, 3) caudal-ventral midline, 4) pubic symphysis- splitting, and 5) pubic plate reflection.

Perineal - permits complete transurethral prostatectomy. This approach gives poor visualization of the prostatic vasculature and vesicourethral anastomosls.

Extra peritoneal - involves extensive soft tissue dissection between the peritoneum and abdominal muscles. This approach is advocated when the presence of large peritoneal adhesions of the prostate are suspected.

Caudal-ventral midline - is considered the best method if the prostate is located forward to the pelvic brim.

Pubis symphysis-splitting - large masses or glands are readily extirpated and this approach is useful for treatment of trauma involving the pelvic urethra and prostatectomy. It presents difficulties in exposure of the prostate in old or large dogs. The pubic symphysis is usually well calcified and difficult to divide

Pubic plate reflection - more desirable in large or old dogs than for small or young ones because of difficulty in splitting the pelvic symphysis without jeopardizing the iliosacral articulation or fracturing the pubic bones. This approach does require more time and special equipment is needed.

VIII. Penis, Prepuce, Scrotum, Testes

Anatomy

The penis is composed of three principal divisions: the root, the body, and the distal free part (subdivided into the bulbus glandis, and the pars longus glandis). The root and body, which are continuous, are made up of corpus cavernosum penis, the ventrally located corpus cavernosum urethrae (containing the penile urethra), and the enlarged proximal end of the OS penis. The corpora contains enlarged venous spaces. The root is attached to the tuber ischii by the right and left crura. Each crus is made up of the proximal part of the ipsilateral corpus cavernosum penis and the ischocavernosus muscle covering it. The body of the penis begins at the blending of the crura, The corpus cavernosum penis arises, one on either side, from the ischial tuberosity, and each runs distally in the dorsolateral part of the body of the penis as far as the OS penis. A fibrous median septum completely separates the right and left cavernous body. Superficially, each corpus cavernosum penis is enveloped by a thick layer of collagenous and elastic fibers, the tunica albugenea. The corpus cavernosum urethra is located in a groove on the urethral side of the penis and surrounds the penile urethra throughout its course. The bulb of the urethra is the bilobed expansion of this erectile body, located between the crura at the ischial arch, The corpus cavernosum urethra narrows in diameter from its origin just within the pelvic cavity until it dips into the glands penis. There it gives off numerous shunts that supply the bulbous glandis with venous blood. It then continues in the pars longa glandis to the external urethral orifice, At the distal quarter of the glands penis, the corpus cavernosum urethrae diverges ventrally from its groove in the OS penis. The bulbis glandis, a cavernous expansion of the corpus cavernosum urethrae, surround the proximal part of the OS penis. Its thickest part and area of greatest potential expansion is located on the dorsal surface of the penile bone. It contains large venons sinnses bound by trabeculae rich in elastic tissue. The OS penis is long and the proximal 2/3 of the bone is indented ventrally by a distinct groove. The corpus cavernosum urethrae and penile nrethra occupy the groove until they diverge from the bone toward the external urethral orifice. The principal source of blood to the penis is the internal pudendal artery, a ramification of the visceral branch of the internal ileac. The internal pudendal artery gives rise to the perineal artery, which supplies the superficial part of the penile root and the perineum. The artery of the penis is that portion of the internal pudendal between the perineal artery and the three principal vessels of the penis: artery of the urethral bulb, deep artery of the penis, and dorsal artery of the penis. The internal and external pudendal veins drain blood from the penis. The paired pudendal nerve and the paired pelvic nerve supply the penis. It receives sympathetic fibers through the hypogastric nerve.

The prepuce extends cranially from the scrotum and is suspended from the ventral abdomen by preputial ligaments and muscles. These modified cutaneous muscles keep the prepuce over the glands penis when the penis is not erect. It is composed of two layers of integument dorsally, except for the cranial 1-3cm, where it is free of the abdominal wall and there are three layers. Ventrally and laterally there are three layers of integument. The outer layer is skin; the inner layers, parietal and visceral, are made up of stratified squamous epithelium which is smooth and thin, and stippled with lymph nodules and nodes. The parietal, or middle, layer is a continuation of the outer skin layer onto the wall of the preputial cavity, and it extends to the fornix of the prepuce The visceral, or inner, layer extends from the preputial fornix to the external urethral orifice, where it is continuous internally with the cavernous urethra, The vascular supply of the prepuce is through the dorsal artery and vein of the penis and a branch of the external pudendal vessels. Sensory innervation of the visceral layer of the prepuce, covering the glands penis, is through the dorsal nerve of the penis to the pudendal. Superficial branches of the ileoinguinal and ileohypogastric nerves innervate the pareital layer.

The scrotum is a membnnous pouch divided by a median septum into two cavities. it is located approximately 2/3 of the distance from the preputial opening to the anus in the dog. The scrotal integument is pigmented and covered with fine scattered hairs. Deep to the outer integument is the dartos, a poorly developed layer of smooth muscle mixed with collagenous and elastic fibers. It forms a common covering for both halves of the scrotum and also helps to form the scrotal septum. Contraction of the dartos muscle causes the integumentary layer of the scrotum to invest the testes more intimately, and thus helps to bring them closer to the body. The principal blood vessel to the scrotum is the external pudendal artery. The genital nerve, a branch of the genitofemoral nerve (from the third and fourth lumbar nerves), innervates the skin of the scrotum, the inguinal region, and the prepuce. The perineal nerve, a branch of the pudendal (from sacral nerves one, two, and three), helps supply this region.

The testes are located within the scrotum, oval in shape and thicker dorsoventrally than from side to side. They are normally positioned obliquely, with the long axis running dorsocaudally. The epididymis is adherent to the dorsolateral surface of the organ, with its tail located at the caudal extremity of the testis, and its head at the cranial end. The surface is covered by the proper vaginal tunic, a serous membrane continuous with the parietal peritoneum of the abdominal cavity. Deep to the proper vaginal tunic is the tunica albuginea, a dense, white fibrous capsule. The testis is secured to the scrotal wall by the proper vaginal tunic. The tunic reflects onto the common vaginal tunic along its epididymal attachment. The scrotal ligament connects the testis and epididymis to the spermatic fascia; the scrotal ligament a vestige of the embryonic gubernaculum testis, runs between the caudal reflections of the vaginal tunics, not entering the vaginal. The spermatic cord and scrotum are the principal supports of the testis. The testicular artery and artery of the ductus deferens supply the testis and epididymis. The veins drain on the right into the vena cava whereas the left sperrnatic vein empties into the renal vein. The spermatic arteries are branches of the aorta and the right artery originates cranial to the left artery; this may be a factor in the right testis being retained more commonly than the left, The nerve supply of the testis is derived from the sympathetic division of the autonomic nervous system, derived indirectly from the fourth, fifth, and sixth lumbar ganglion of the sympathetic trunk. The hypogastric nerve is thought to supply only the proximal end of the ductus deferens. The blood vessels and smooth muscle fibers in the testis receive a sympathetic nerve supply, but the seminal epithelium and the interstitial secretory tissue do not. Elimination of the sympathetic nerve supply to the testis is followed by degeneration of the seminal epithelium and hypertrophy of the interstitial secretory tissue, considered to be the result of paralysis of the blood vessels in the spermatic cord and testis.

Pathophysiology

Trauma to the penis is not a common problem, but may occur with a pelvic injury. There are usually varying degrees of hemorrhage from the prepuce; infections may occur, The denuded areas also provide a favorable site for the development of fibropapillomas. The OS penis can be fractured as a result of trauma. The distraction of the fracture fragments or the swelling associated with inflammation and healing can occlude the urethra. Neoplasms of the glands penis and penis are not common. Squamous cell carcinomas may be seen on the epithelium of the glands or a hemangiosarcoma of the cavernous body. The transmissable venereal sarcoma can be found on the glands penis, prepuce, perineum, and rectum.

Acquired phemosis is caused by inflammation, edema, neoplasia, and cicatrical contraction following healing of a wound. The extension of the penis from the sheath is prevented. Paraphemosis is usually associated with sorne degree of phemosis; the glans will remain outside the prepuce and become congested and discolored. The preputial ring swells and tightens so that with time the glands becomes necrotic and the urethra is obstructed.

The scrotum is subject to many forms of trauma; e.g., lacerations, ulcers, necrosis, edema, and hemorrhage. Two common neoplasms of the scrotum are mast cell tumor and reticulum cell carcinoma. Both tumors tend to recur locally and metastasize through the lymphatics to the inguinal and preputial lymph nodes. Scrotal ablation is mandatory and follow up radiation therapy is advised, Chronic hyperplasia of the scrotum is common in old dogs. The ventral scrotal skin becomes thickened, wrinkled, deeply pigmented, and devoid of hair. There is hyperplasia of the epithelium and underlying connective tissue. Extensive infection may result, and castration and scrotal removal are indicated.

Orchitis, testicular neoplasia, and torsion of retained and non-retained testicles are the main indications for castration. The most significant inflammations of the testes are of bacterial origin and develop hematogenously, or perhaps sometimes by retrograde progression through the vas deferens from infected accessory glands. In the latter instance, an epididymitis will precede the orchitis. Acute inflammation of the tunica vaginalis commonly accompanied by an epididymitis. The common route of pathogenesis is by reflex along the vas deferens from the bladder, urethra, or prostate of infection chiefly by E. Coli, Proteus Vulgaris, and other miscellaneous organisms. An acute inflammatory response is either the epididymis or testis is usually suppurative with the formation of one or more abscesses. The acute inflammations are usually centered on the ducts with the usual degenerative and desquamative changes in the epithelium and there is edema and mononuclear cell infiltrate in the surrounding stroma, Healing occurs with dense cicatrisation which in the epididymis will cause some tubular obstruction with spermatocele formayion. Primary testicular tumors are quite common in older dogs. The three main types include the interstitial cell tumor, the seminoma, and the Sertoli-cell tumor. These types occur with almost equal frequency in the dog population. The dog can have one tumor type or all three simultaneously. One or both testes are involved and the tumors are grossly visible. It is a well-documented fact that testicular neoplasms occur with greater freqnency in retained or cryptorchid testes, There are no specific clinical signs associated with testicular neoplasia except the functional Sertoli- cell tumor The main features of the Sertoli-cell tumor are alopecia, attraction of other male dogs, and gynecomastia; however, only 1/3 of the dogs with Sertoli-cell tumors manifest signs of a functional neoplasm. Clinical problems in which there is a high incidence of testicuar neoplasia are cryptorchidism, prostatic hyperplasia, perianal gland adenoma or adenocarcinoma, perineal hernia and physical asymmetry of the testes,

Surgery

Surgical correction of phemosis - the preputial orifice is enlarged by incising the ventral preputial margin and suturing the preputial skin and mucous lining of the prepuce with fine PDS suture material. Care must be taken so as not to make the orifice too large to cause protrusion of the glands penis or paraphimosis.

Surgical correction of paraphemosis - castration can be performed to correct the prepuce. A dorsal longitudinal incision is made at the preputial orifice and extended through the skin to the mucous lining with a fine PDS suture.

Partial ostectomy - after the penis and prepuce are cleansed, a urethral catheter is put in place. The skin is incised along the ventral midline of the prepuce from two cm caudal to the urethral orifice to one cm beyond the caudal end of the OS penis. The preputial mucosa is incised and the penis is lifted from the incision; a sterile towel is placed under it. The dorsal vessels of the penis are isolated temporarily occluded with clamps or ligatures (blood should be allowed to flow every ten minutes to prevent thrombosis). The penile mucosa and underlying erectile tissue on the ventral aspect of the penis are incised. The retractor penis muscle is reflected caudally. The urethra is identified by the presence of the catheter, and an incision is made on the ventral midline down to the urethra; the urethra should not be incised. The incision is continued through the fascia between the urethra and OS penis to the top of the OS penis. The erectile tissue is carefully reflected from the lateral surface of the groove wall as close to the bone as possible. The urethral catheter is then removed, and beginning at the cranial end, the entire length and depth of the one wall of the groove is removed in small sections, using small rongeur forceps. All bleeding points are ligated after removal of the clamp on the dorsal arteries. The urethral catheter is reinserted to help avoid the urethra during suturing. Complete hemostasis may not be obtained until the tunica albuginea is closed with simple continuous sutures of 3-0 PDS. Cranially, this suture includes the mucous membrane of the penis. The fascia over the caudal part of the penis and the preputial mucosa are sutured with 3-O PDS and the skin is closed with nonabsorbable suture. The catheter should be left in place for 4-5 days if the catheter was incised during the surgical procedure.

Partial amputation of the penis - indications include primary trauma or neoplasia, or extensive disease of the prepuce. It is performed distal to the fornix of the prepuce and the bulbus glandis and necessitates transection of the pars longa glandis and the OS penis. The penis is withdrawn from the prepuce or, if necessary, it is exposed by dividing the prepuce along the ventral midline. A tourniquet is placed near the fornix of the prepuce around the bulbus glandis. The prepuce is retracted with umbilical tape. Care is taken to preserve the urethra. An incision is made through the pars longa glandis lateral to the OS penis and urethra on both sides, i.e., starting with a No. 12 Bard- Parker blade, directing the blade laterally and distally approximately 0.5cm. The urethra is carefully dissected from the groove in the OS penis to a point 2-3 mm proximal to OS penis transection. (A catheter placed in the urethra greatly facilitates the dissection.) One-half to one cm of the urethra is preserved distal to the transection. The OS penis is transected with bone-cutting forceps at the base of the pars longa glandis flaps. The tourniquet is loosened to identify arteries, which are ligated. The pars longa glandis flaps are apposed by inserting simple interrupted sutures of 4-0 PDS. One-half of the preserved length of the urethra is incised longitudinally along the ventral midline. The urthral margin is sutured to the epithelial margin of the penis with 4-0 PDS in a simple interrupted pattern.