CVC Highlight: How to think outside the litter box: Managing cats with nonobstructive idiopathic interstitial cystitis

A typical cat with idiopathic cystitis is 1 to 10 years old, lives indoors with people, uses a litter box, and consumes 75% or more of its diet in dry food. The cat may be unusually nervous or needy, overreactive to its environment, and often suffers from other medical conditions, such as obesity or upper and lower gastrointestinal, respiratory, and skin problems.1

Current evidence suggests that some cases of idiopathic cystitis represent a systemic disorder variably affecting the bladder and other organ systems rather than a primary bladder disease. Idiopathic cystitis may account for clinical signs related to the urinary system of irritative voiding (dysuria, stranguria, pollakiuria, gross hematuria, periuria) in up to 70% of cats that are less than 10 years old. In contrast, only about 5% of cats older than 10 years with such signs have idiopathic cystitis—instead, more than half of the cats in this age group have bacterial urinary tract infections with or without urolithiasis.2

DIAGNOSIS

Abdominal palpation sometimes reveals pelvic organ pain, bladder wall thickening, and a small bladder. In cats with recurrent signs of lower urinary tract disease, we recommend survey abdominal radiography and double-contrast cystography or abdominal ultrasonography to rule out calculi and anatomic defects and identify bladder wall abnormalities.

Urinalysis in affected cats may reveal hematuria, proteinuria, crystalluria (which is likely secondary to sterile neurogenic inflammation that leads to proteinuria and increases urine pH so that struvite crystals precipitate), and high specific gravity. In cats with lower urinary tract signs and a urine specific gravity < 1.025, investigate a systemic problem such as renal disease, diabetes mellitus, or hyperthyroidism.

TREATMENT RATIONALE

Increased noradrenergic outflow (catecholamine secretion) in response to activation of the stress response system may increase epithelial permeability and activate local neurogenic inflammation in the bladder and elsewhere.3 Thus, it is crucial to decrease noradrenergic outflow by identifying and reducing factors that may contribute to a cat's stress and epithelial compromise, such as living indoors with people, poor welfare, and inferior husbandry. In addition, providing systemic analgesia helps break the bladder pain-inflammation cycle.

TREATMENT

Clinical signs of a first or a recurrent episode of idiopathic cystitis usually resolve in about 85% of affected cats within a week with or without treatment, but about 50% of cats have another episode within a year. The signs of idiopathic cystitis are distressing to owners, and irritative voiding is presumably stressful for affected cats. Thus, we recommend the following treatment regimen.

We treat the distress and pain associated with acute flares of idiopathic cystitis with acepromazine and buprenorphine. The injectable form of acepromazine may be given orally (2.5 mg b.i.d. to t.i.d.), although some cats will exhibit hypersalivation. In these cats, the oral form may be used—1/4 of a 10-mg tablet in a Greenies Pill Pocket (Nutro Products) or made up as a suspension and administered with an oral syringe. The injectable form of buprenorphine is given orally at 5 to 20 µg/kg two to four times a day for three to five days—buprenorphine is absorbed across the buccal mucosa.

We also recommend enriching the environment of indoor cats, because captivity and housing with people and other cats or other environmental challenges may elicit stress responses in some cats. Although extensive indoor housing in an unenriched environment doesn't cause idiopathic cystitis, it may contribute to its development and ongoing occurrence. We have found that about 80% of cats with recurrent idiopathic cystitis respond to successful implementation of environmental modification.

Environmental modification

Environmental modification is an important aspect of treatment.4,5 The litter box must be a clean, acceptable, and accessible place to encourage the cat to eliminate normally. Anything that hampers litter box use may increase the time the cat retains urine between eliminations. Prolonged exposure of the bladder wall to urine in cats with increased bladder wall permeability may increase access of "toxins" (e.g. acid, potassium, nitrogenous wastes) to suburothelial structures, which also may activate local inflammatory mechanisms. Litter box design, numbers, locations, obstacles, and cleaning schedules as well as litter type all influence a cat's litter box usage and should be discussed with clients.

Decreasing the cat's urine specific gravity below 1.030 is a treatment target and can be attempted by switching from dry to canned food or adding water to dry or semi-moist diet formulations, as long as the diet change or new diet is not aversive to the client or the cat. Owners also can encourage these cats to drink more water from their cats' preferred water sources such as a fresh-dispense bowl or even a running faucet in the sink, or by adding meat or fish-flavored ice cubes to their water if they like that. Acidifying the urine to minimize struvite crystalluria is usually not indicated.

Conflict between cats or other animals in the household or threats from outdoor cats can be a source of stress, so talk with owners about providing separate resources that each cat can use without interference from other animals.

Providing opportunities for owner-cat interaction and activity such as playing with toys that mimic prey motion or that intermittently release food are helpful. Methods to increase indoor space that the cat uses include providing vertical and horizontal scratching surfaces as well as objects to climb and areas in which to hide, perch, look outside, and rest undisturbed.

Based on our clinical experience, we also encourage owners to use synthetic feline facial pheromone products to augment other enrichment efforts. Feliway (Ceva Santé Animale) can be sprayed in the affected area of the environment or dispersed into larger areas by using an electric diffuser.

Additional environmental modification and medical management

If a cat continues to have signs of idiopathic cystitis, review the environmental modifications with the owners to find out what worked and what did not work and why. Suggest alternative or additional environmental modifications if needed, and consider including increased supervised exposure to the outdoors for some cats.

We sometimes prescribe amitriptyline (5 to 12.5 mg/cat orally once a day, always using the lowest possible dose) or another tricyclic antidepressant when environmental modifications as described above have not sufficiently reduced the cat's clinical signs. We taper the dose gradually and stop it whenever possible after at least three months of use, and we use the drug cautiously if at all in cats with heart disease. We also perform a complete blood count and serum chemistry profile to monitor the platelet and white blood cell counts and liver enzyme activities before and at one, three, and six months during therapy.

Additional medical therapy may include increasing the dose of buprenorphine. Unfortunately, glucosamine6 and pentosan polysulfate7 have been found to be ineffective therapy for feline idiopathic cystitis.

FOLLOW-UP

If a cat's clinical signs do not resolve or if the signs recur, you can perform additional diagnostic evaluation (repeat the complete blood count, serum chemistry profile, and urinalysis, and consider performing or referring the cat for cystoscopic evaluation) to rule out problems other than idiopathic cystitis.

Controlled clinical trials may provide additional information about the best approach to managing cats with idiopathic cystitis, but in the interim we have had success with the aforementioned environmental and medical management procedures.

Dennis Chew, DVM, DACVIM

C.A. Tony Buffington, DVM, PhD, DACVN

College of Veterinary Medicine

The Ohio State University

601 Vernon L. Tharp St.

Columbus, OH 43210

REFERENCES

1. Buffington CA, Westropp JL, Chew DJ, et al. Risk factors associated with clinical signs of lower urinary tract disease in indoor-housed cats. J Am Vet Med Assoc 2006;228(5):722-725.

2. Westropp J, Buffington CAT, Chew DJ. Feline lower urinary tract diseases. In: Ettinger SJ, Feldman EC, eds. Textbook of veterinary internal medicine. St. Louis, Mo.: Elsevier-Saunders, 2005;1828-1850.

3. Buffington CAT. Comorbidity of interstitial cystitis with other unexplained clinical conditions. J Urol 2004;172(4 Pt 1);1242-1248.

4. Westropp JL, Buffington CAT. Feline idiopathic cystitis: current understanding of pathophysiology and management. Vet Clin North Am Small Anim Pract 2004;34(4):1043-1055.

5. Buffington CAT, Westropp JL, Chew DJ, et al. Clinical evaluation of multimodal environmental modification (MEMO) in the management of cats with idiopathic cystitis. J Feline Med Surg 2006;8(4):261-268.

6. Gunn-Moore DA, Shenoy CM. Oral glucosamine and the management of feline idiopathic cystitis. J Feline Med Surg 2004;6(4):219-225.

7. Chew DJ, Bartges JW, Adams LG, et al. Randomized, placebo-controlled clinical trial of pentosan polysulfate sodium for treatment of feline interstitial (idiopathic) cystitis, in Proceedings. Am Coll Vet Intern Med, 2009.