How to Understand Canine Blood Tests

When you take your dog to the veterinarian, the vet may order blood work. Blood tests aren't just for sick or old dogs; they serve as a baseline for healthy pets and are useful if your pup's going to undergo anesthesia. The results are categorized to provide an assessment of the health of the body's major organs. Blood tests include the complete blood count and blood chemistries to evaluate organ health.

Blood tube
A small vial of blood contains a wealth of information about your dog's health.
credit: Yen Teoh/iStock/Getty Images

Complete Blood Count

The complete blood count, or CBC, provides a wide variety of information about your dog's health by measuring the three types of blood cells: red blood cells (RBC), white blood cells (WBC) and platelets (PLT). Produced in the bone marrow, red blood cells distribute oxygen throughout the body, carrying oxygen in hemoglobin (HGB). Increases in the red blood cell count values indicate dehydration or illness causing high RBCs; a lower RBC points toward anemia and lowered capacity for carrying oxygen. Other red blood cell values include the mean cell volume (MCV), packed cell volume (PCV), hematocrit (HCT), red cell distribution width (RDW) and reticulocytes (RETIC). White blood cells are divided into two categories: white blood cells and the leukocyte differential. The differential measures the different types of white blood cells and includes neutrophils (NEU), eosinophils (EOS), lymphocytes (LYM), granulytes (GRANS), monocytes (MONO) and basophils (BASO). White blood cells battle infections, so elevated values indicate infection, while a lower WBC may be from bone marrow weakness. The different types of white blood cells indicate different issues; for example, lymphocytes are responsive to stress, which can indicate tissue injury. Platelets help your dog's blood clot; a low PLT may occur if the bone marrow is damaged. A complete blood count is routine for a dog with vomiting, diarrhea, fever, loss of appetite, weakness and pale gums.

Organ Health

A blood chemistry test will provide the vet a clear picture of how your dog's kidneys, liver and pancreas are functioning. The four kidney measurements are blood urea nitrogen (BUN), creatinine (CREA), phosphorus (PHOS) and calcium (Ca). High values in all represent loss of kidney function; a high BUN also can indicate liver and heart disease as well as dehydration and shock. CREA can help the vet determine if the cause of the elevated BUN is related to the kidney or some other organ. Liver function is measured by six values: alanine aminotransferase (ALT), alkaline phosphatase (ALKP), gamma glutamyl transferase (GGT), albumin (ALB), total bilirubin (TBIL) and bile acids. Elevated ALB can indicate dehydration, while lower levels point to loss of liver function as well as kidney or gastrointestinal disease. When other values show increases, such as ALT and ALKP, liver abnormality may be indicated. Pancreatic health is measured by amylase (AMYL) and lipase (LIPA). Elevated levels of both enzymes can indicate pancreatitis, kidney disease and gastrointestinal disorders.

Proteins and Electrolytes

By studying your dog's proteins and electrolytes, the vet can gain a clearer picture of what's going on in his body. The protein profile measures total protein (TP), globulin (GLOB) and ALB. Dehydration, inflammation and infection can be indicated with elevated values, while kidney disease, immune deficiencies and blood loss are associated with decreased values. Sodium (Na), potassium (K) and chloride (Cl) are part of the electrolyte panel. Elevated sodium indicates dehydration, while decreased sodium is seen with diarrhea, vomiting, Addison's disease and kidney disease. The opposite is true with potassium; high levels of potassium point to kidney disease and Addison's disease, as well as dehydration; low potassium are possible with diarrhea or vomiting. High Cl indicates dehydration and loss is associated with diarrhea and vomiting.

Other Values

Other information gleaned from your pup's blood includes glucose (GLU), creatine kinase (CK), cholesterol (CHOL), triglycerides (TRIG), thyroxine (T4) and aspartate aminotransferase (AST). A host of conditions can be indicated in these values, such as diabetes mellitus for a high GLU value and hypothyroidism for a low T4 number.

Context is Important

If your dog's blood test reveals a value outside a normal range, it's important to keep calm. Medication and diet can affect the values in a blood test. As well, the blood values are only part of the picture your vet is looking at when he's evaluating your dog's health. Medical history and symptoms are part of the diagnostic process, as well as other tests, such as urinalysis and radiographs.