Urinalysis is a grouping of tests performed on a urine sample. There is a wealth of information that can be gained from analyzing urine. Proper collection and preparation of the sample will maximize the value of the results.
Collecting the sample is the first step. Veterinarians use various techniques to get samples. We can perform a procedure called cystocentesis wherein the urine is obtained directly from the bladder using a needle. Catheterization is done by passing a tube up into the bladder. Manual expression involves gentle pressure to the bladder externally to cause urine flow. Owners are often asked to collect free flow samples, especially from their dog. With cats, we can also use a special litter to collect the free flow samples.
Timing plays an important role for the best samples. A first morning urine should be the most concentrated, which gives us valuable information about how the kidneys are working. Because the urine chemistry changes after a meal, a fasted sample is preferable. Once a sample is obtained, it is ideal to run the tests as soon as possible. If there is going to be a delay, the sample must be refrigerated.
The basic urine tests look at the physical, chemical, and microscopic qualities of the urine. We do all these tests right here at Colborne Street Pet Hospital. Physical tests are about color, quantity, clarity, and concentration. Chemical tests are done with a urine stick. This is a plastic strip with 9 tiny pads that change color when the urine is applied. The stick tells us about the presence of blood, sugar, protein, and other chemical changes like pH. Once these tests are done, an accurately measured sample is put in a centrifuge to help concentrate any solids that are suspended in the urine. We take the resulting sediment and do a thorough microscopic exam looking for crystals, bacteria, blood, and other cells that may be markers for disease. Occasionally we need to do more specialized testing, such as culturing for identification of bacteria, or measuring particular compounds. These tests are done by our lab, and we prepare the samples for them.
Urinalysis is far more useful that just checking for a bladder infection. It can alert us to kidney disease before blood tests become abnormal. It helps us screen for diseases like diabetes, Cushings and Addisons. Abnormal urine crystals are a marker for antifreeze poisoning, Dalmation urates and liver disease. Bladder and prostate cancers can shed cells into the urine that we will see with our microscope. We joke about urine being liquid gold, but it is indeed an treasure house of information and an invaluable diagnostic tool.