Laboratory Results
The results of laboratory tests are compared to reference ranges that are established by measuring the laboratory parameters in a group of healthy dogs. The reference range may differ between laboratories as they are measuring a different group of dogs.
When reading the results of laboratory tests it's important to understand that a perfectly healthy dog may have one or two test results outside the so-called "normal" range. The abnormal result may be "normal" for your dog or the results may have been influenced by drugs, intestinal upsets or extreme activity. Many drugs, vitamin supplements and herbal remedies can affect lab results. Please be sure your vet knows about any supplements so that they can be considered when interpreting laboratory results.
Bile acids are produced by the liver and are involved in fat breakdown. A pre and post meal bile acid test is used to evaluate the function of the liver and the blood flow to the liver. All dogs on Phenobarbital should have a bile acid test done at least every 6 months.
Your vet will ask you to fast your dog for 12 hours prior to the first blood draw. Your dog is then fed a high fat meal such as canned dog food. Another blood sample is drawn two hours (may vary according to the lab your vet uses) after eating. These two blood tests will measure liver function when the liver is at rest and when the liver is challenged with a fatty meal. Please be careful during the fast as even a small amount of food can affect the fasting blood test. As a general rule medications can be given during the fast, however, they must not be given with food.
There is a relatively new test called a urine bile acid test that can be collected from one sample of urine, however, this test is not proven to be as accurate as the blood bile acid test.
The complete blood count measures the number and type of cells circulating in the bloodstream. There are three major types of blood cells in circulation; red blood cells (RBC), white blood cells (WBC) and platelets. White blood cells include neutrophils, lymphocytes, monocytes, eosinophils and basophils. Blood cells are produced in bone marrow with the exception of lymphocytes which are produced in the lymph glands throughout the body.
Red Blood Cells are responsible for carrying oxygen and carbon dioxide throughout the body. Iron deficiency will lower red blood cell count. If red blood cells are significantly reduced it may indicate hemorrhage, parasites, bone marrow disease, B-12 deficiency, folic acid deficiency or copper deficiency. An increase usually indicates dehydration.
Neutrophils can be decreased in dogs with bone marrow disease, some viral diseases or from cancer chemotherapy drugs. Neutrophils are increased in dogs with inflammation or infection of any part of the body or from the use of cortisone-type drugs.
Lymphocytes may be increased when infection is present and decreased from severe stress, diarrhea or the use of certain drugs such as prednisone.
Monocytes may be increased in dogs with chronic infections.
Eosinophils and basophils are increased in dogs with allergic diseases or parasitic infections such as worms or fleas.
Low platelet counts occur if the bone marrow is damaged and can't produce them or if the platelets are destroyed at a rate faster then normal.
Packed Cell Volume (PCV) is another measure of red blood cells which compares the number of cells to the total volume of blood.
Note: An elevation of one enzyme may not be indicative of any particular condition or disease. With most conditions several enzymes will be abnormal.
Albumin is a small protein produced by the liver. Albumin acts as a sponge to hold water in the blood vessels. When blood albumin is decreased, the pressure created by the heart forcing blood through the blood vessels causes the fluid to leak out of the blood vessels and accumulate in body cavities such as the abdominal cavity or in tissues as edema. Albumin is decreased if the liver is damaged and cannot produce an adequate amount of albumin or if albumin is lost through damaged intestine or in the urine due to kidney disease. The only cause of increased albumin is dehydration.
ALT (alanine aminotransferase) ALT is an enzyme produced by liver cells. Liver damage causes ALT to increase in the bloodstream. Elevations in ALT may be caused from acute liver disease, poisoning hepatitis, pancreatitis, or from the use of Phenobarbital or cortisone-type drugs.
ALP (Alkaline Phosphatase) ALP is found in a variety of tissues including the intestine, liver, bone and kidneys. Elevations are very common for dogs taking Phenobarbital and do not necessarily indicate liver disease in these cases.
Amylase is an enzyme produced by the pancreas and the intestines. Amylase helps the body breakdown sugars. Amylase may be increased in the blood in dogs with inflammation or cancer of the pancreas, renal failure or from the use of corticosteroids.
AST (Aspartate aminotransferase) AST occurs in the liver and all types of muscle. Elevations in AST may indicate liver disease, muscular diseases or heart disease.
Bilirubin is produced by the liver from old red blood cells. Bilirubin is increased in the blood in dogs with some types of liver disease, gallbladder disease or in dogs who are destroying red blood cells faster than the normal rate.
BUN (blood urea nitrogen) is influenced by the liver, kidneys and by dehydration. BUN is a waste product produced by the liver from proteins and is eliminated from the body by the kidneys. A low BUN may be seen with liver disease and an increased BUN indicates kidney disease.
Calcium in the bloodstream originates from the bones and levels are influenced by diet, hormone levels and blood protein levels. Abnormally high calcium in the blood is seen in dogs with hypercalcaemia, hypoadrenocorticism, primary renal failure or overdoses of vitamin D. Low calcium levels may indicate hypocalcaemia, hypoalbuminaemia, malabsorption, or acute pancreatitis. Muscle twitches may occur in dogs with decreased levels.
Cholesterol is a form of fat. Some of the more common causes of elevated cholesterol are hypothyroidism, Cushings disease, diabetes, acute pancreatitis and kidney diseases. High cholesterol does not predispose dogs to heart disease as it does in people.
Creatinine is a waste product that originates from muscles and is eliminated from the body by the kidneys. An elevation of creatinine is due to kidney disease, seizures or dehydration.
GGT (Gamma-glutamyltransferase) Circulating GGT is considered to originate from the liver. Elevations are caused from the use of glucocorticoid therapy or liver disease.
Globulins (Glob) are decreased with problems with antibodies, immunodeficiency viruses or risk of infectious disease. Increased levels may indicate stress, dehydration, blood cancer, allergies, liver disease, heart disease, arthritis or diabetes.
Glucose is only accurate if a proper fast has preceded the blood draw. The most common cause of elevations in glucose levels is improper fasting. If glucose levels are high with a proper fast it would indicate diabetes mellitus, steroid therapy, acute pancreatitis or hyperadrenocorticism. Low glucose levels indicate hypoglycemia, liver insufficiency or insulin overdose.
Lipase elevations indicate pancreatitis.
Phosphorus is affected by diet, parathyroid hormone and kidney. Decreased levels shows overactive parathyroid gland and malignancies, malnutrition and malabsorption. Increases are seen with under active parathyroid gland and kidney failure.
Total Protein includes albumin and globulins. Total protein can be increased from infection, inflammation, dehydration or when the dog's immune system is being stimulated to produce large amounts of antibodies. It is decreased from liver insufficiency, or when the dog has an abnormal immune system and can't produce antibodies.
Triglycerides are another form of fat and are responsible for gross lipemia often seen in serum or plasma samples. Elevations are caused by insufficient fasting prior to blood sample, hypothyroidism and diabetes mellitus.
Specific gravity is a measurement of how concentrated the urine is. Certain diseases such as renal impairment and diabetes insipidus affect a dogs ability to concentrate urine.
Urine protein is usually only seen in trace amounts as the kidney normally does not allow protein to get through. When protein is present it indicates damage to the kidneys.
Glucose should not be seen in the urine. However, when blood sugar levels become very high as with diabetes mellitus, it exceeds the kidney's capacity to keep sugar out and glucose is seen in the urine.
Urine sediment can be examined for solid material such as cells, bacteria, crystals and casts. Red blood cells in the urine indicate inflammation, certain tumors or blood clotting disorders. White blood cells and bacteria are seen in infection. Crystals may be normal or may indicate infection, liver disease, toxin ingestion or bladder stones.
Meyer & Harvey, Veterinary Laboratory Medicine Interpretation and
Diagnosis
Tilley, LP, The 5 Minute Veterinary Consult
