Blood Testing for Your Dog or Cat
A Necessary Diagnostic Tool for Evaluating Your Pet's Health
Mar 6, 2009
Blood testing is frequently used as a first step in diagnosing disease in an ill animal. It is also commonly used to screen apparently normal healthy animals for early signs of disease.
Types of Blood Tests for Animals
There are numerous types of blood testing available for animals. We will discuss the most common blood tests for your dog or cat.
Most blood screening for animals will include:
- Complete Blood Count
- Blood Serum Chemistry Profile
- Thyroid T4 Level
- Heartworm Test
- Feline leukemia and/or Feline AIDS (for cats)
Complete Blood Count
A complete blood count (CBC) allows your veterinarian to examine your pet's red blood cells and white blood cells. An abnormal CBC can be indicative of:
- anemia
- infection
- inflammation
- blood cancer
Serum Blood Chemistry Profile
A serum blood chemistry profile examines a variety of different blood tests, including:
- BUN and creatinine, which are kidney function tests. Abnormally high values can indicate kidney disease, dehydration or post-renal disease located in the ureter, bladder, or urethra.
- Liver enzymes (such as ALT and SAP) and bilirubin (both direct and indirect) are used to look at liver function. Abnormal values may indicate liver disease or compromise.
- Blood glucose tests are used to evaluate pancreatic function. Elevations can be indicative of diabetes. Low blood glucose readings can be indicative of liver or kidney disease, missed meals, or overdosage of insulin.
- Amylase and lipase are also used to evaluate pancreatic function but are no longer considered accurate methods of evaluation.
- Albumin and globulin levels combine to produce the total protein level. Abnormalities may indicate dehydration, disease of the kidneys, liver or intestinal tract, or an active immune system.
- Calcium levels are also usually examined and can indicate bone content. Abnormal calcium levels can be seen with certain types of cancers as well as many other diseaases.
- Electrolye levels, including phosphorus, potassium and sodium, are also frequently part of the serum chemistry tests. These can be abnormal in kidney or liver disease, intestinal disease, adrenal disease and many others.
Thyroid T4 Levels
Thyroid levels are, as the name implies done to evaluate thyroid function.
- In dogs, hypothyroidism is a common disease and is evidenced by low thyroid T4 levels.
- In cats, hyperthyroidism is more common and elevated thyroid T4 levels are seen.
If abnormal thyroid T4 levels are detected, many veterinarians recommend further testing with more specialized thyroid tests, such as the free T4 by electrodialysis and/or the TSH (thyroid stimulating hormone) test.
Heartworm Test
Heartworm antigen testing is considered routine for dogs and is becoming increasingly routine for cats as well. Many veterinarians advise yearly heartworm screening even when monthly heartworm preventative medications are given.
In areas where ticks are common on dogs, heartworm testing is frequently combined with testing for common tick-borne diseases, such as Lyme disease, ehrlichiosis and anaplasmosis. This test is known as the Idexx SNAP 4DX. (The previous SNAP 3DX did not include the anaplasmosis test.)
Feline Leukemia and Feline AIDS Screening
Currently, the American Association for Feline Practitioners (AAFP) recommends that the leukemia and AIDS status be known for every cat. The AAFP recommends testing:
- whenever a new kitten or cat is added to your household
- whenever your kitten or cat is in contact with another cat with a positive or unknown status
- before vaccinating against feline leukemia or feline AIDS
- before entering a multi-cat household
- any time a cat or kitten becomes ill
Very recently, a new test has become available for cats which incorporates the feline leukemia and feline AIDS tests with a heartworm antigen test.
In the event of a positive blood test for either feline leukemia or feline AIDS, your cat's veterinarian may recommend retesting at a later date or further testing which may be more sensitive to indicate whether your cat has a true infection.
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