Diagnosing Cat Urinary Infections

Dog Breeds

Urinary tract infections in cats are diagnosed through urine cultures or a urinalysis test. Before these tests can begin, a clean sample of the urine must be obtained. A clean urine sample is vital to an accurate urinary tract infection diagnosis.

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Introduction

Urinary tract infections in cats usually are diagnosed through urinalyses and blood tests. In cases of persistent or recurrent infection, radiographs (x-rays), ultrasonography and urine culture may be appropriate additional diagnostic tools.

Diagnosing Urinary Tract Infections in Cats

Urinalysis

A routine urinalysis is one of the most valuable tests available to veterinarians to assess feline wellness. Urinalysis is a normal part of a thorough, routine check-up and is critical in cases of suspected renal, bladder or other urinary tract disorders. Urinalysis is easy and inexpensive to perform and involves four major steps after the urine sample is obtained: visual examination, chemical analysis using pre-treated dipsticks, measurement of urine specific gravity and microscopic examination of the urine.

The preferred method of collecting urine is by cystocentesis, which involves inserting a needle directly through the abdominal wall, puncturing the bladder and removing the sample by aspiration through a syringe. This procedure takes only seconds, is performed while the cat is awake and causes little to no discomfort. While routine urinalyses in dogs tend to be performed on a freshly voided urine sample collected mid-stream in a clean, dry, sterile container, it is very difficult to collect urine this way in cats. Voided samples are also prone to contamination, which can produce false positive test results. Urine can also be collected through a urinary catheter, although this method also has a risk of contamination. The urine assessment should be done within one hour of collection, regardless of collection method; if that is not practical, the sample should be refrigerated and then returned to room temperature at the time of the examination.

The attending veterinarian will assess color, turbidity/clarity, volume, odor and overall appearance of the urine by visual and olfactory inspection. Next, she will immerse a multi-test reagent strip (“dipstick”) into the urine and compare the reactions (color-changes) with different test pads. She will assess the specific gravity of the urine using an instrument called a refractometer. The next step is to centrifuge (“spin down”) the sample and examine the centrifuged sediment microscopically to analyze those parts of the urine that do not contribute to the chemical reagent strip changes. At each stage of the urinalysis, proper handling of the specimen is essential. The results of these procedures will provide an enormous amount of information to the veterinarian, including the urine pH and levels of protein, glucose, ketones, bilirubin, blood, nitrites and other components that can reflect the function or dysfunction of the cat’s kidneys and other organs. Microscopic assessment provides information about whether the urine contains abnormalities such as casts, crystals, bacteria, white blood cells, yeast or other organisms, many of which can be diagnostic of urinary tract infections or other disorders.

Urine Culture

Urine culture and sensitivity are the gold standard for diagnosing urinary tract infections in all species, including cats. Cultures should be performed on sterile samples preferably obtained by cystocentesis to reduce the chance of contamination. Culture is also highly recommended for UTIs treated with, but unresponsive to, antibiotics. The urine sample normally is sent to an outside laboratory for culture. The urine will be placed on appropriate growth media, and after several days it will be assessed for bacterial, fungal, viral or yeast growth, depending upon which organism is suspected. Different growth media are required to culture different organisms. The laboratory will identify the particular organism(s) involved, enabling the attending veterinarian to select the appropriate antibiotic or other course of therapy. Culture is usually performed only if an initial course of empirical antibiotic treatment is unsuccessful in resolving the infection.

Testing for Underlying Conditions

Routine blood work (complete blood count and serum chemistry profile) is normally done as part of the initial diagnostic data base in cats suspected of having a urinary tract infection, together with the urinalysis. The results of these blood tests may reveal a predisposing condition or disease that caused or contributed to a UTI, such as renal (kidney) disease, neoplasia (cancer) or hyperadrenocorticism (Cushing’s disease). For recurrent or persistent UTIs, abdominal radiographs (x-rays) can be helpful to identify uroliths (stones), enlarged prostate or other abnormalities. Abdominal ultrasound is useful to assess the structure of the kidneys, urinary bladder and urethra. Radiographic contrast studies are available in many veterinary hospitals, as well. Uncomplicated UTIs are normally treated with antibiotics empirically. If the infection does not resolve, or if it resolves but recurs, further diagnostics are necessary.

Treatment Options

Symptoms and Types