Bloodwork and Other Lab Tests for Pets

Laurie Anne Walden, DVM

Photo by Daniel Sone, National Cancer Institute.

Laboratory testing of blood, urine, and stool samples is routinely done for animals. Abnormalities often show up on lab tests before an animal has obvious symptoms. Even healthy pets need to be tested regularly for parasites. Well-animal tests can detect problems early and help veterinarians track changes over time. These are some of the reasons your veterinarian might recommend lab tests for your pet:

• Routine wellness screening
• Senior pet screening: more comprehensive tests, possibly more than once a year
• Testing before anesthesia
• Diagnostic testing for animals with symptoms
• Monitoring the course of a chronic disease
• Medication monitoring: some examples are insulin, seizure medications, and some pain medications

 
Complete Blood Count
A complete blood count measures the number, size, and shape of each type of cell in the blood.

• Red blood cells: These cells carry oxygen throughout the body. Anemia (low red blood cell count) is caused by decreased red blood cell production, red blood cell destruction, or blood loss. Measures of red blood cell size and shape give clues to the cause of anemia.
• White blood cells: This group of cells includes neutrophils, basophils, eosinophils, lymphocytes, and monocytes. White blood cells are part of the immune system. Infections, parasites, allergies, inflammation, and cancer can change the numbers and proportions of white blood cells.
• Platelets: Platelets are small pieces of cells that help the blood clot.

 
Blood Chemistry Panel
Blood chemistry tests measure substances in the blood that indicate changes in organ function or other biological processes. Blood chemistry analysis is run as a panel of many individual tests. A chemistry panel doesn’t always give a diagnosis for a sick animal, but the results can help the veterinarian narrow down the list of possibilities. Veterinary laboratories offer many chemistry panels for different species and diagnostic needs. A small panel that’s sufficient for a young animal before routine surgery might not be appropriate for an ill animal or an older pet. These are a few of the tests commonly included in chemistry panels:

• Kidney enzymes: These enzyme levels increase when kidney function decreases. Kidney disease is very common in cats, so senior cats should have kidney enzyme levels checked regularly.
• Liver enzymes: Some markers of liver function are liver specific; others are affected by changes in other organs too. Changes in liver enzyme levels need to be evaluated alongside the rest of the chemistry panel and often warrant further tests.
• Glucose: Glucose is a type of sugar. Diabetes and other conditions cause an increase in the blood glucose level. Low blood glucose, or hypoglycemia, has a number of causes.
• Proteins: Panels typically include total protein and also the individual proteins albumin and globulin. Dehydration, liver disease, inflammation, and other diseases can alter protein levels.
• Electrolytes: Sodium, potassium, calcium, and phosphorus levels are affected by a number of diseases and are included in many chemistry panels.
• Thyroid hormones: Thyroid tests are not included in all chemistry panels, but feline panels typically include at least 1 type of thyroid hormone because thyroid disease is so common in cats. Diagnosing hypothyroidism (low thyroid function) in dogs usually requires additional thyroid function tests.

 
Urinalysis
Analysis of the urine includes specific gravity (a measure of urine concentration), pH, chemistry results like glucose and protein levels, and microscopic evaluation for cells, crystals, and bacteria. Urinalysis can reveal urinary tract infection, support a diagnosis of diabetes, and help evaluate the function of the kidneys and other organs. A complete laboratory analysis—especially for a senior pet—should include urinalysis.
 
Parasite Tests
Parasites are very common in pet animals (unless they have received regular parasite prevention as recommended by a veterinarian). Many of the parasites that pets carry are contagious to people. At least once a year, pets should have a stool test for intestinal parasites like hookworms and roundworms. Dogs should also have a yearly blood test for heartworm disease.

Public domain image source: National Cancer Institute, Daniel Sone (photographer)

---