Urine Testing: Why Test Your Cat's Urine?

Having regular veterinary examinations performed for your cat is the best way to keep your cat healthy. In most cases, your veterinarian will likely recommend blood and urine testing as part of a thorough examination. If your cat is not feeling well, blood and urine testing may be necessary to diagnose your cat’s illness.

We’ve talked about common blood tests and what we can learn from them in a previous post. Today, I’d like to talk about urine tests and explain what your veterinarian may be looking for in your cat’s urine.

Urinalysis is, by far, the most commonly performed urine test. A urinalysis (or UA as it is often called) is actually made up of many different tests. A typical urinalysis tests for the following:

• Visual Evaluation: If your cat’s urine is discolored or has an abnormal clarity (i.e. cloudy urine for instance), these findings will be noted here. Normal urine should be yellow and clear.
• Urine Specific Gravity (USG): This is a measure of the concentration of your cat’s urine. Urine passed through the kidneys with no change in concentration has a specific gravity of 1.008 to 1.012. This urine is termed isosthenuric. Healthy cats should be able to produce relatively concentrated urine, often with a USG of 1.050 or higher. If the urine is too dilute, measured as an abnormally low urine specific gravity, your cat may be suffering from a disease condition that affects his ability to produce concentrated urine. This may result from diseases such as diabetes, kidney disease, and many others. It is important to remember that USG can change drastically between one urine sample and the next. In some cases, multiple urine samples may need to be tested to determine whether a cat is producing consistently dilute urine. Evaluating USG in conjunction with clinical signs, physical examination findings, and blood test results is also useful and will help your veterinarian determine the significance of the USG result or other abnormal laboratory results.
• Urine pH: pH is a measurement of acidity, in this case the acidity of your cat’s urine. The lower the pH number, the more acidic the urine. The pH of urine will impact which types of stones and/or crystals can form in your cat’s urine. Some types of stones form in urine with lower pH values and others are more likely to be found at higher pH values. Some types of bacteria also prefer specific pH ranges. Manipulating the pH value can be useful for handling some urinary tract issues.
• Glucose: Commonly referred to as “sugar”, glucose in the urine is most frequently an indication of diabetes although stress can cause glucose to show up in the urine in some cases also.
• Ketones: Ketones are most often found in the urine of diabetic animals. Ketosis occurs when glucose cannot be utilized for energy production. Body fat is then broken down into ketones that can pass through the kidneys into the urine. Ketones in the urine quite often indicate a crisis situation.
• Bilirubin: Bilirubin, a product of red blood cell breakdown, is normally removed in the liver and becomes part of the bile. When it is found in the urine, it can be an indication of liver disease or other illnesses, such as bleeding disorders.
• Blood: Blood may be found in the urine for a number of different reasons. Referred to as hematuria, blood in the urine can be an indication of urinary tract infection (UTI), cystitis, kidney or bladder stones, kidney disease, cancer of the urinary tract, or bleeding disorders.
• Protein: Protein in the urine can be caused by kidney disease as well as other illnesses.
• Urine Sediment: Examining the urine sediment involves separating the cells and other solid matter from the fluid portion of the urine through centrifugation. The sediment is examined for red blood cells, white blood cells, bacteria, casts, crystals, mucous, or other cells. Essentially, this portion of the urinalysis looks at the cellular and solid component of the urine, searching for abnormal numbers of cells or other materials which should not normally be present in the urine. It can provide additional clues as to the state of your cat’s health.

In some cases, your veterinarian may also perform even more specialized urine testing:

• If a urinary tract infection is suspected, your veterinarian will probably recommend a urine culture and sensitivity. A urine culture tests for bacteria in the urine and identifies the specific type of bacteria in the event of a positive response. The sensitivity tests the efficacy of various antibiotics against that bacteria, providing your veterinarian with information about which type of antibiotic is most likely to resolve your cat’s urinary tract infection.
• In some cases, a protein:creatinine ratio may be necessary to quantify the degree of protein loss through the kidneys and evaluate its significance.
• There are many other specific urine tests that your veterinarian may find necessary depending on your cat’s individual situation.

Dr. Lorie Huston

Image: Thinkstock

WRITTEN BY

Lorie Huston, DVM

Veterinarian