INAPPROPRIATE ELIMINATION IN CATS

PART 2

Dr.  Kari Mundschenk

Director, American Association of Feline Practitioners

Last month we started our discussion on inappropriate elimination which encompassed those problems leading to cats urinating or defecating in places other than the desired litter box.  Together, these problems make up the number one reason for the surrender of cats in the United States.  As discussed, there are two categories of causes for this problem which, unfortunately, can interlap.  These categories are medical and behavioral.  Furthermore, behavioral causes can persist long after the medical cause has been resolved.  (I.e. post surgery).

Behavioral causes of elimination disorders were classified into five main categories:

1.       substrate aversion

2.      substrate preference

3.      litter box aversion

4.      location aversion

5.      location preference

As mentioned, your veterinarian will work with you to determine the category your cat fits into and many times a simple change in the environment will improve the problem. 

Before everything can be blamed on behavior, a thorough medical examination must be performed in order to rule out medical causes of elimination disorders, both fecal and urinary.  The initial workup will include a urinalysis with culture and abdominal imaging, usually with radiographs but may also be ultrasound.  Blood analysis with viral testing may also be advised after a review of history, age and examination findings.   The remainder of this talk will focus on urinary causes of inappropriate elimination.

Medical causes of elimination disorders can be categorized into those diseases within the FLUTD (feline lower urinary tract disease) syndrome, anatomical, trauma, neoplasia or other mass effect, constipation or megacolon and neurologic.

The clinical signs of lower urinary tract disease include hematuria, increased frequency of urination +/- dysuria or anuria (decreased or absent urine output).  If urinary obstruction is present, abdominal discomfort, licking of the perineum and if left untreated, depression, coma and death from secondary renal failure may be present.  Many times, owners call thinking their cat is constipated but at clinical presentation, there is a large, tense and painful abdomen.  In contrast, cats with cystitis, the bladder is small, firm and painful, but the cat is generally systemically well.

Depending on presentation, the disease will be broken down into nonobstructive, obstructive, behavioral (discussed in part 1) and true incontinence.  The most common causes of nonobstructive disease in cats aged 1- 7 years of age are idiopathic cystitis and uroliths.  If cats are under 1 year of age, uroliths or anatomical abnormalities are most common.  In older cats, the incidence of bacterial infection and neoplasia increases often requiring special tests.    Obstructive disease is usually caused by the present of a urethral plug, lodged uroliths, impacted crystals or severe spasms of the urethra.  True urinary incontinence can arise from trauma to the musculoskeletal or neurologic system; breed related myelodysplasia as seen in the Manx, or from diseases which cause an increase in urine output which becomes uncontrollable for the patient. 

Management of lower urinary tract disease requires separation of the problem into 2 categories, obstructed and non-obstructed, either with or without a behavioral component.  Obviously, our goal with obstructed cats is to relieve the obstruction after sufficient information as to location and cause of obstruction has been obtained.   Usually pressure is relieved by removing the urine from the bladder during a cystocentesis followed by placement of a urinary catheter.    Once the obstruction is relieved, attention to correcting the systemic effects of the obstruction will be addressed.  Usually these cats will be hospitalized for 3-5 days to monitor renal enzymes, potassium levels and urination.  Post obstruction diuresis is a common problem which requires appropriate fluid therapy to maintain proper hydration level.  Additionally, many medications used to prevent spasms take a few days to take effect.  Recurrence of obstructions does occur, most within 6 months, so owners need to be monitoring their cats.  Many times, cats will be placed on specific diets aimed at controlling their issue.  Additionally, fresh water and a clean litter box are paramount at assisting in controlling the problems.

Bacterial infection in cats does occur but is present in only 3% of urinary disease.  Age, dilute urine, positive viral status and presence of a urinary catheter do increase the risk of infection.  Urinary tract infection is not diagnosed by cytology; a urinary culture is mandatory.  Due to the existence of resistant bacteria and the fact that many antibiotics will lead to multi-drug resistance, choosing an antibiotic should be based on culture results.  Additionally, a follow up culture should be obtained 5-7 days into therapy.  If the medication is working, continue treatment for the prescribed time with another culture 1 week after discontinuing treatment.  If not working, refer to the susceptibility report for an appropriate antibiotic. 

The formation of urinary calculi usually occurs with struvite and oxalate.  Most calculi form in the urinary bladder but can also be found in the renal pelvis and ureter.  If removed, they should always be identified.  Unlike the dog, they do not form secondary to infection.  There is no breed predisposition for struvite calculi although Burmese, Himalayan and Persian cats do seem predisposed to oxalate calculi.  Surgery can be used to remove bladder calculi.  Dietary modification and frequent monitoring are required to prevent/control further problems.   It is important to note that crystals can be visualized on normal urinalyses but that does not mean calculi or disease is present or that it will ever occur.

Idiopathic cystitis is the most common cause of non-obstructive disease in cats under 7 years of age.  Many times there is no specific cause of the inflammation but recent research shows that stress is a common inducer.  The lining of the bladder is composed of GAG proteins, the same are found in the stomach.  During stress, there is a breakdown of the protective lining which exposes the underlying tissue to urine.  The urine is a very irritating substance which induces inflammation.  INFECTION IS PRESENT IN < 3% OF CASES SO ANTIBIOTICS ARE NOT RECOMMENDED.  After ruling out other causes of urinary problems, treatment should be aimed at controlling discomfort, addressing the stress factor and providing an appropriate diet and fresh water.  Most of these flare ups resolve in 3-5 days which in the past made people believe antibiotics were working.  Instead, the inappropriate use of antibiotics has led to the formation of resistant bacteria for both cats and humans in their environment. 

Neoplasia, trauma and constipation issues should be addressed when found.  Additionally, a neurologic examination and blood pressure analysis should be performed. 

Unfortunately there is no clear cause to feline lower urinary tract disease.  Research is still continuing but it appears that the syndrome is caused by a multitude of factors including viruses, stress hormones, breed and diet.  Treatment and control should be directed at controlling the discomfort, preventing recurrence and most importantly, preventing the cat from progressing into the behavioral form of inappropriate elimination by making necessary changes in the environment.