Veterinary Blood Test
Why does your veterinarian recommend routine testing of blood and urine, particularly in senior dogs and cats? The goal of every veterinarian is to identify any problems your pet may have very early, because sometimes, early detection can mean better treatment options or possibly slowing the progression of a disease. It is amazing what can be learned about your pet’s health with a few tests conducted on samples of blood and urine.

How Blood and Urine Samples Work

Drawing the blood sample or catching a bit of urine is the first part of the equation. So what happens after your veterinarian obtains samples of your pet’s blood and urine? The blood sample is usually divided into two different types of tubes — a red top and a lavender top. The red-topped tube allows the blood cells to clot so the fluid in the blood, called serum, can be tested for levels of certain chemicals and enzymes. This serum can be used for a number of different tests that will tell your veterinarian how some of your pet’s internal organs are functioning. Your veterinarian may refer to these tests as a “chemistry panel” and may even request specific panels that can help diagnose problems with your pet’s thyroid, kidneys or liver, just to name a few.

The lavender-topped tube contains a chemical that prevents the blood from clotting so that the red blood cells (which carry oxygen to tissues) and white blood cells (which help fight infections) can be counted. This is called a CBC (complete blood count). A drop of this unclotted blood will also be placed on a slide and viewed under a microscope because a lot can be learned from looking at the shape and condition of your pet’s blood cells.

And that just covers the basic blood tests. A basic urine test (urinalysis) can provide additional information on many health conditions. Tests conducted on a urine sample provide information on concentration (called specific gravity) and pH (acidic or alkaline) and detect items that should not routinely be found in urine (such as protein and glucose). The sediment in the urine also can be examined under a microscope for the presence of bacteria or crystals.

It may seem like the blood and urine samples are taken into the back room and your veterinarian magically appears with results, but the evaluation of these samples is quite sophisticated and reviewing the results is an art in which your vet has been trained. Many veterinary hospitals can conduct several of these blood and urine tests on-site. There are also diagnostic laboratories that will not only conduct these tests (and others) but that have experts in many areas of veterinary medicine who can consult with your veterinarian.

Depending on the results of the urinalysis, CBC and chemistry panels, your veterinarian may order additional tests. When blood and urine test results are combined with other diagnostic tools — such as ultrasound and radiographs (X-rays) — and a physical exam, an accurate accounting of your pet’s health can be established so treatment options can be discussed and implemented.

The Older They Get: Common Health Problems in Senior Cats and Dogs

The risk for some diseases increases with the age of your pet. Listed below are some common problems found in senior dogs and cats, many of which can be present without your pet showing any outward signs until the disease is quite advanced. So the next time your veterinarian recommends that blood be drawn for a specific test or for wellness screening, remember: Early detection can make a difference!
  • Overactive thyroid (hyperthyroidism)
  • Decreasing kidney function
  • Diabetes (especially in overweight cats)
  • Fatty liver (lipidosis)

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