Urinary tract pitfalls (Proceedings)

1. If you don't look, you don't know.

It's not enough to take radiographs if you don't take the views that you need to provide essential information. A series of radiographs will be reviewed that demonstrate the pitfall of omitting key information. Other examples of omission of key information will also be examined.

2. What you see is not always what you get.

How many times have you identified bacteria on a urinalysis, but failed to grow any organisms with a urine culture? Examples of cases will be given which offer explanations for this circumstance and other puzzling results.

3. Insanity is expecting to achieve a more favorable result with the same approach that has failed to produce the desired result multiple times.

When the administration of multiple antibiotics doesn't resolve persistent clinical signs such as hematuria it's time to take a fresh look at the problem. Ideas for resolving hematuria and other annoyingly persistent clinical problems will be presented.

4. It may look like a duck, quack like a duck, and walk like a duck, but sometimes it's only a distant relative.

Sometimes renal failure isn't as straight forward as it seems. Case examples will be given as illustrations.

5. Just because you can do something, doesn't mean you should do something.

Some urinary tract abnormalities may warrant monitoring rather than direct intervention. Criteria will be given for determining when monitoring the patient is a better option than treatment in select cases.

Pitfall Pounders

Points to remember about urinalyses and bacterial identification:

     • Ideally urine samples should be evaluated within 30 minutes of obtaining the specimen.

     • Urine should be refrigerated until examination is possible. It should be gradually warmed to room temperature prior to examination.

     • Ideally both an unstained specimen and a stained specimen should be examined. Determination of the presence of bacteria is best done on a stained specimen.

     • When bacteria are not cultured from a urine sample which was believed to contain bacteria on sediment examination, operator error is the most common reason for that circumstance to occur.

     • Obtaining an accurate bacterial culture from urine may be facilitated by using transport tubes to inhibit growth of contaminants or by performing in-house plating of urine.

What can I do about recurring urinary tract infections and FLUTD?

     • First review the therapy attempted previously:

          1. Was a culture with a sensitivity performed by an appropriate method for the suspected site of infection?

          2. Does the patient have an untreated or inadequately treated concurrent disease predisposing the pet to UTI (relapse vs reinfection)?

          3. Are you certain that the owner has been carrying out treatment appropriately?

          4. Was the duration of therapy inadequate due to the presence of a complicating factor such as:

               a. the presence of a treated or untreated concurrent predisposing disorders

               b. the patient being an intact, male dog

               c. administration of medication for other conditions that interferes with successful antibiotic eradication

               d. inaccurate localization of site of infection?

     • If recurring urinary tract infection remains a problem in spite of addressing the above factors or because a predisposing factor cannot be eliminated, you may wish to try long-term low-dose therapy (1/3 of typical daily antibiotic dose given once a day in the evening for 6 months or pulse therapy (typical antibiotic dose one week out of every month or 3days out of every week indefinitely). Changing to a different class ofantibiotics to achieve greater tissue penetration may also be helpful. For prevention, especially of E. coli, consider the use of a urinary antiseptic once the UTI is undercontrol (methenamine hippurate- 500 mg/dog PO q12 hrs or 250 mg/cat PO q12 hrs).Methenamine will not be effective with urease-producing organisms like Staph and often requires a urinary acidifier to be given concurrently to be effective.

     • Canine and feline Enterococcal UTIs Enterococcus organisms are gram positive, catalase negative cocci. This type of bacteria can be part of the normal flora of the GI and biliary tracts. Enterococcus is commonly found in patients that have received antibiotics and can be associated with urinary catheterization Antibiotics that have been found to be effective are amoxicillin, (90% effective), amoxicillin-clavulanic acid (90% effective), imipenem (90% effective), and enrofloxacin (50% effective). Some Enterococcal infections are resistant to common antibiotics. Recommendations for resistant/recurring infections with Enterococcus are as follows:

Single Isolate, No Clinical Signs

Do not treat. Infection can be transient and may resolve on its own, especially after withdrawal of antibiotics.

Multiple Organisms, With or Without Clinical Signs

Do not include Enterococcus in the antibiotic treatment plan.

Single Growth, Clinical Signs Present

Amoxicillin (25 mg/kg PO q12 hrs) + Gentamicin (8 mg/kg subQ q24 hrs) for 7 – 10 days

Or

Chloramphenicol (40 mg/kg PO q8 hrs in the dog and 12 mg/kg PO q12 hrs in the cat)

     • What else can I do to treat cats with feline lower urinary tract disease?

Determine if the patient's FLUTD has an underlying cause (bacterial, urolith-related,neoplastic, etc.) that can be treated in a specific way or if it is truly idiopathic (FIC = feline idiopathic cystitis). FIC is a diagnosis made by exclusion of other possible causes and the presence of compatible signs (hematuria, pollakiuria, periuria, and/or dysuria). Although many treatments have been advocated, only feeding a moist food has been shown to be statistically significant in bringing about improvement. It is believed that the moist food makes a difference by causing urine dilution. Increasing daily water intake by dividing the moist diet into multiple small meals, adding broth or water to foods, increasing dietary salt content (avoid in CRF cats) and using pet water fountains may also be helpful in accomplishing urine dilution. Recent emphasis has been placed on stress reduction, environmental enhancements, and appropriate litter box management with some evidence of decreasing clinical signs from FIC. Although short-term use of mitriptyline (5 – 10 mg/cat/day) has not proven beneficial in cats with FIC, it is possible that long-term use may reduce clinical signs. Amitriptyline has anti-inflammatory, anticholinergic, analgesic, and antihistaminic properties which are felt to be potentially helpful in these patients. Other medications with anti-inflammatory, analgesic, or epithelial protective activity may provide relief from discomfort in FIC-related episodes. These include buprenorphine (0.02 – 0.04 mg/kg q8 – 12 hrs transmucosally, meloxicam (0.1 mg/kg PO q24 hrs for 3 – 4 days), gabapentin (1.3 mg/kg/day PO), and pentosan polysulfate sodium (50 mg/cat PO q12 hrs).

Points to remember about prevention of struvite and calcium oxalate crystals/uroliths in cats:

     • If the patient does not have a history of urolith formation or urethral plugs of crystals and mucus, remember that the presence of crystals does not necessarily mean that the patient will develop uroliths. Place the patient on a canned diet appropriate for its age and body condition, advise the owner to watch for any signs of lower urinary tract disease, and resist the temptation to "treat" crystals.

     • Place the patient on a diet suitable for the prevention of both struvite and oxalate calculi such as Hill's c/d Multicare® Purina's Urinary St/Ox Feline Formula®, or Royal Canin's Veterinary Diet feline Urinary SO.®

     • In cats at risk for both struvite and oxalate crystals/uroliths consider using preventative measures, including diet, for calcium oxalate crystals/uroliths since an option exists formedical dissolution of struvite uroliths but not calcium oxalate uroliths.