I get quite a few questions about all the lab tests that are done by Veterinarians. What are they for and what do they tell us are the most frequently asked questions from pet owners.

Over the next couple of posts I'll jump in on this topic and try to explain some of the more common tests.

Most of these tests involve blood and urine and they are very similar to the same types of tests your physician orders for you when you are ill.

So why do Vets order these tests in the first place?

These tests help us narrow down the list of possible problems and they can help us monitor treatment progress too. They give us important information on how the body is responding to a disease challenge or how a certain organ system might be functioning.

It takes skill and an understanding of the whole animal to interpret these results. That's one reason many different tests are needed to properly evaluate a potential medical problem. Taken in isolation, one test or one abnormal test may be meaningless, but taken as a whole we can learn a great deal about what is going on.

The most common diagnostic blood test run in most Veterinary Hospitals is called the Complete Blood Count or CBC for short. This test tells us a lot about the different types of cells in the blood stream and how they change based on a pet's health. This test evalutes both red blood cells, cells called platelets and the numerous types of "white" blood cells that form important components of our immune system.

Red blood cells are very important and help carry oxygen picked up in the lungs to the various tissues in the body. These cells are created in the bone marrow and have a life of about 100 days in the circulation. As they age they are removed by the spleen and liver and replaced by the bone marrow.

Changes in red blood cells may indicate problems with production or increased destruction and can give us information about anemia and the source of anemia. Blood loss can also result in anemia. Too many red blood cells in dogs is most often the result of dehydration. Dogs and cats that live at higher elevations may also have higher numbers of RBC's.

The CBC also measures hemoglobin, the substance in red blood cells that actually carries the oxygen molecule.

There are many different causes of anemia and an analysis of the RBC's and hemoglobin can tell us alot about the source of the anemia and the potential causes. For instance, blood loss from internal bleeding may not be obvious on a physical exam, but the CBC would give us a clue about internal blood loss.

The other component of the CBC is an analysis of the white blood cell types. That's a post all in itself and we'll cover that on Monday.