It's very common in cases of illness for a Veterinarian to order a CBC, Chemistry Panel and a urinalysis as the baseline laboratory tests to help make a diagnosis. These three tests taken together can tell us a great deal about a pet's health and about the fucntion or organs like the liver, kidney, pancreas and others.
In the case of the urinalysis it's critical to evaluate these results along with the results of the CBC and the chemistry profile. Taken together, the results can narrow the list of possible causes of disease.
Today we'll cover the specifics of the urinalysis.
The urinalysis begins with the collection of the urine sample. It's best to perform the urinalyis at the same time as the other tests and before therapy has begun. The easiest way to collect urine is to catch the dog or cat during the act and fill a clean container with 3-5 cc's of urine. Catching the sample midstream is always preferable to reduce contamination from the external genitalia.
The next least invasive method is to manually express the bladder. Manual expression is common and a midstream sample is best. Care must be taken to avoid trauma, especially in cases where urethral obstruction or bladder stones are suspected.
Insering a catheter is another option and care must be taken to avoid introducing bacteria into a sterile bladder. Cystocentesis is a big word for sticking a needle into the bladder through the abdominal wall to obtain urine. As painful as that sounds, many dogs and cats handle cystocentesis quite well and this is the preferred method of urine sampling in many Veterinary Hospitals. Cyctocentesis, done properly, gives us a smaple free of contaminants.
Once the urine sample is obtained it is examined for color and the obvious presence of blood and inflammatory debris. A sample is examined under the microscope for the prese
nce of bacteria, inflammtory cells, crystals and other components of the urine sediment.
The urine specific gravity, or the ability of the kidney to concentrate the urine, is examined with a special instument called a refractometer.
The next step is to use what is called a dipstick to measure several other parameters. These dip sticks are commercially available and are made with reagents that react with the urine sample to give a readings on pH and the presence or absence of various markers in the urine sample.
Besides pH the dip sticks can give important information on urine glucose, urine protein content, blood, bilirubin, ketones, urobilinigen, nitrite and the presence of white blood cells. This article from the University of Georgia, College of Veterinary Medicine, gives a complete run down on the interpretation of the various dip stick tests.
Lab tests like the one's we've covered over the past week are critical tools your Veterinarian will use to help diagnose your pet's medical condition. In Veterinary medicine these tools are particularly important.
We have to rely on the history we get from you along with a good physical exam, lab tests, x-rays and other diagnositic tools to figure out what is going on.
After all, it's the rare dog or cat that can actually tell us "where it hurts".