Your veterinarian can diagnose many common problems involving the urinary system by taking a medical history, performing a physical examination, and performing tests on the cat’s blood and urine. The history might include information regarding changes in how much water your pet drinks, how often it urinates, how much urine it produces, how the urine looks, and how your pet behaves. Your veterinarian will also need information about what medications your pet has taken or is currently taking, your pet’s appetite and diet, changes in body weight, and previous illnesses or injuries.
When performing the physical examination, your veterinarian will feel your cat’s kidneys and bladder, examine its genitalia and, sometimes, its rectum. If your pet has trouble urinating, your veterinarian may also want to perform a neurologic (nerve and brain) examination. In addition to a physical examination, there are many additional tests a veterinarian might sometimes perform in the case of a urinary disorder. These include blood tests, blood pressure tests, urinalysis (laboratory tests on your pet’s urine), other urine tests, x‑rays, contrast x-rays (tests in which a special dye is given to outline the urinary tract on the x-ray), ultrasonography, biopsies, and cystoscopy. Cystoscopy involves inserting a tube with a small camera at the tip into the urethra. This allows the veterinarian to see problems or changes in the urinary tract more clearly.
Urinalysis is a laboratory test that evaluates urine. It is one of the most important tools a veterinarian can use to diagnose urinary tract problems. Many tests are performed as part of a urinalysis. These include the specific gravity (which measures concentration), appearance, and pH of the urine. Urinalysis also tests for the presence of certain chemicals or substances in the urine, such as sugar, ketones (a byproduct of the body’s processing of fat), bilirubin (a pigment produced when the liver processes waste), blood, and protein. The urine sediment is also examined under a microscope to look for things such as red blood cells, white blood cells, other cells, bacteria, crystals, and renal casts (tube-shaped particles that come from the kidney).
Urinalysis is best performed on fresh urine samples because delays can cause inaccurate results. Your veterinarian will recommend an appropriate way to collect your cat's urine. If you collect a urine sample at home, keep the sample refrigerated and let your veterinarian know what time it was collected.
If a urinalysis finds protein in the urine, an additional urine test called a urine protein:creatinine ratio may be necessary. If your veterinarian suspects your cat may have a urinary tract infection, a bacterial culture may be performed instead of, or in addition to, urinalysis. Cystocentesis, a procedure in which urine is removed directly from the bladder by use of a needle inserted through the abdomen, is the preferred way to collect urine for a bacterial culture.
Also see professional content regarding the urinary system.