Colic: The deciding factors – from referral to surgery (Proceedings)

All colics are not created equal

• Thorough and timely assessment play a significant role in successful treatment of the critical colic

• Making a decision for referral early can significantly influence the outcome

• Survival is directly correlated to early diagnosis and treatment

Field diagnostics

• Components of the colic examination

o Physical exam

o Rectal

o Abdominocentesis (belly tap)

o Ultrasound

o Nasogastric intubation

• Physical exam

o Pain status

o Heart rate

• Normal = 36-44

o Temperature

• Normal = 99.5-101

o Respiratory rate

• Normal = 12-16

o Mucous membranes

o Normal = pink, moist, CRT <2 sec

o Gastro-intestinal sounds

• Present? Not present? Increased? Decreased? Gas?

o Evidence of pain

o Abdominal distention

• Examination per rectum

o Slow initial entry into rectum

o Left dorsal quadrant to find the spleen

o Clockwise examination

o Detect all fixed structures

o Buscopan (0.3 mg/kg) can facilitate rectal

• Rectal examination

o What you are feeling for:

• Abnormal distention.

• Abnormal position.

• Abnormal mass.

• Abnormal peritoneal surface.

• Abdominal ultrasound

o Can be performed in the field

o Preferable a 5-10 MHz microconvex probe or 2.5-5 MHz sector scanner

o Can sometimes use linear probe percutaneously if it is at lease a 5 MHz, but is more difficult

o Can use reproduction probe transrectally sometimes to evaluate SI distention and motility palpated rectally

o Abdominal ultrasound

• The sweet spots:

• Inguinal region

• Just abaxial to midline

• Identify position of spleen and locate left kidney (for nephrosplenic rule-out)

• Abdominocentesis

o Can be performed in the field

• Teat cannula or 18 gauge – 1.5" needle

• Aseptic prep

• At most dependent portion of the abdomen

• Just abaxial to midline

• Gross analysis of fluid – serosanguinous or not?

o Can carry refractometer – evaluate protein (normal = < 1.0 g/dl)

o Nasogastric intubation

o Reflux and gastric lavage

o Fluid obtained should be less than 2 L

o Perform lavage if significant feed material obtained – gastric impaction??

o If > 2 L net back – do not give oil, H2O or electrolytes

Making a diagnosis

• Sequence of diagnosis

o Categorize as ileus, obstruction, strangulation, enteritis or peritonitis

o Identify segment of intestine involved

o Categorize the severity

o Look for specific signs related to a specific disease: Make a diagnosis

o Risk factors for a specific disease

Decision for referral

• 2-4 % of horses with colic will need surgery

• The decision for surgery is best made early

Questions:

o Is pain responsive to analgesia?

o Do exam findings indicate surgery?

o Do exam findings indicate extensive medical treatment (enteritis)?

o Is horse insured?

o Is surgery an option?

• Surgeon's basis for referral (Peloso JG, Proc AAEP 1996; 42:250-253)

o 100%- Unrelenting pain

o 96%- History of increasing pain

o 95%- Marked abdominal distention

o 92%- Chronic pain for 5 days

o 87%- Analgesics don't relieve pain

o 85%- Serosanguinous peritoneal fluid

o 79%- Increased protein in peritoneal fluid

o 89%- Purple/cyanotic MM

o 95%- HR, CRT, and PCV increased on second examination

o 89%-Gaseous distention of SI

o 92%-Feed impaction not resolved in 3 days

• Surgery is a diagnostic tool

• Refer for a second opinion rather than surgery

• Refer early to increase survival

• Pre-plan surgical referral for colic

Protocol for referral

• Stomach tube in place if refluxing

• Administer flunixin meglumine if > than 6 hours from 1st dose

• Administer antibiotics +/ -

• Administer intravenous fluids

• Case dependent

• Provide analgesic/sedative for transport

How is the decision for surgery made once referred?

• History

• Referring veterinarian's findings

• Repeat diagnostics - what has changed?

• Rectal exam

o In a multi-center study an abnormal rectal exam was most important factor in determining need for surgery (Reeves et al AJVR 52(11):1903-07, 1991)

o Not a sensitive diagnostic

o A normal rectal exam does not rule out a surgical problem, but an abnormal rectal is not definitive

• Reflux

o Obstruction or Enteritis?

o Pain is responsive to gastric decompression in enteritis

o Enteritis usually has large volumes of foul smelling fluid

• Ultrasound

o Marked SI distention, no motility, and thickened wall are indications for surgery

o Can confirm nephrosplenic, inguinal hernia, diaphragmatic hernia, intussusceptions

• Peritoneal fluid

o Serosanguinous

o Normal values

• Protein= 0.7 - 1.5 g/dl ???

• WBC= 200-3,000/ul, ratio of neutrophils to mononuclear cells = 2:1

• RBC= rare

o Simple obstruction

• Normal fluid

• Increased protein

• Normal RBC and WBC

• Degenerate WBC increase with longer duration of obstruction

o Strangulation obstruction

• Increased protein >2.0 g/dl

• Increased RBC early > 20000/ul

• Increased WBC as lesions progresses; 5000 to 50,000 WBC/ul

• WBC degeneration and intracellular bacteria with intestinal necrosis

o Thromboembolic colic and peritonitis

• Protein >2.0 - 6.5 g/dl

• RBC normal to serosanguineous

• WBC normal to >400,000 /ul

• Free and intracellular bacteria

o Proximal enteritis

• Protein; 2.0 to 6.5 g/dl

• RBC; variable

• WBC; normal (increased later in disease)

o Indications for surgery

• Serosanguineous; RBC > 20,000/ul

• Acute increase in WBC >5,000/ul with > 90% neutrophils (+)

• Increased protein (+)

• Intracellular bacteria (+)

• Blood work

o Changes in WBC

• ↓ WBC of <4000 cell/µl – consumptive process

• Endotoxemia from strangulation, enteritis/colitis

• ↑ WBC >18,000 cell/µl likely non-surgical, infectious

o PCV

• Hydration status

• Circulatory status – markedly increased with shock

o Total protein

• Lost through diseased gut

• ↓ indicates GI loss and disease

• Decreased or normal TP in face of markedly elevated PCV is sign of significant GI compromise

o Blood gas / chemistry

• Metabolic derangements (acidosis/alkalosis)

• Electrolyte levels

• Renal values (BUN/creatinine) for hydration

• Lactate (normal = < 2 mmol/L)

• Marker or peripheral perfusion and elevations secondary to hypoxia

• Important indicator of systemic illness and dehydration

• Can be prognostic indicator: horses with lactate > 11.2 mmol/L have poor prognosis

o Response to treatment

o Uncontrollable pain

• # 1 is level of pain and response to analgesia and/or fluid therapy

• Secondary considerations:

o Rectal examination

o Abdominocentesis

o Physical exam findings

• Pain non-responsive to analgesia is biggest indicator for surgery

• Surgery itself is a diagnostic tool....

• Always better to err on the side of surgery, and operate on a few that don't have a surgical problem, than wait too long on a horse that does

Outcome and recovery

• Small intestine

o Strangulating lesion

• Lipoma

• Mesenteric rent

• Epiploic foramen entrapment

• Hernia

o Enteritis

• Not typically a surgical lesion

• Does cause severe pain from distention

o Factors influencing survival

• Resection or not

• Influenced by early referral

• Type of resection performed

• Jejunojejunostomy – 81-91% short term survival

• Jejunocecostomy – 71-76% short term survival

• Long term no difference between two

• Necessity for second surgery during hospitalization

• Development of ileus

• Short term survival:

o 49% (1974-1980, 1968-1986)

o 85-92% (1994-1999)

• Long term survival >7 months

o 52% (1987-1991)

o 75% (1994-1999)

• Percentage of survival has increased over time with better surgical techniques and post-operative care

• Large intestine

o Displacement

o Impaction

o Segmental infarction

o Torsion

o Factors influencing survival

• Simple large colon displacements - > 80%

• Large colon volvulus:

• Survival 12-60%

• 3% if treated less than 4 hours from onset of signs

• Time from onset to correction plays significant role in survival – greater than 4 hours significantly reduces survival

• Recovery

o 4 weeks of stall rest with hand walking followed by 4 weeks of small paddock turnout

o Complications such as laminitis or incisional infection will prolong activity restriction

o Rarely send home when intensive treatment is needed

• Myth: My horse will not be useful following colic surgery

• Fact: Following appropriate recovery period and no significant complications horses should return to previous activity and level of performance

o In 100 cases 91% returned to expected level of performance (Launois T et al Equine Colic Research Symp 2005: 53-55 )