Serial determinations of serum amylase in conjunction with serum lipase provide the best practical indication of pancreatic
function. Amylase is produced in a variety of tissues including the salivary glands, small intestine, and pancreas. Most serum
lipase is derived from the pancreas. Excess serum lipase is easily filtered through the kidneys so serum lipase concentrations
tend to remain normal in early stages of pancreatic disease. Gradual increases may be seen as pancreatic disease progresses.
In chronic pancreatic disease, damaged pancreatic cells are replaced with connective tissue that cannot produce pancreatic
enzyme. This information all sounds good, but the most common reason for increased serum amylase and lipase in older dogs
and cats is intestinal disease and not pancreatitis.
Blood glucose measurements provide a useful indicator of the pancreatic islet cells activity. Traditional glucose test methods
have high degrees of interferences, especially in hemolyzed, icteric or lipemic serum samples. Serum fructosamine concentration
is a more specific indicator of pancreatic islet cells activity than is blood glucose concentration. Fructosamine, a glycosylated
serum protein, provides an indication of the average blood glucose concentrations during the previous one to three weeks.
Glucose binds to hemoglobin and produces glycosylated hemoglobin. Increased blood glucose concentrations increase the binding
of glucose to hemoglobin that results in an increased glycosylated hemoglobin value. The glycosylated hemoglobin concentration
is then an indication of the average glucose concentrations during the lifespan of erythrocytes. Since erythrocyte lifespan
is approximately 120 days in dogs and 65 days in cats, the glycosylated hemoglobin concentration is a reflection of average
glucose concentrations during the preceding three to four months in dogs and two to thre months in cats. Thus, glycosylated
hemoglobin is an indicator of the blood glucose concentration during a longer period of time than is either a single blood
glucose measurement or fructosamine concentration.
In-house automated chemistry analyzers are being used more frequently in most veterinary practices. These in-house tests provide
quicker results and allow for more flexibility. However, there is also more chance for errors to occur because of the method
used or the analyzer. To avoid errors, staff members must observe all protocols when performing in-house testing and be familiar
with how to use the equipment.
Tests for urinary ketone bodies may also be used for monitoring insulin therapy in diabetic dogs and cats. However, in some
animals with diabetic ketoacidosis no urinary ketone bodies are detected, because the commonly used urinary tests for ketone
bodies detect only acetone or acetoacetate.
Older dogs and cats entering the veterinary practice today are sick and require immediate point-of-care. Immediate point-of-care
begins with collection of accurate case history followed by performing a thorough physical examination. Thereafter, samples
are collected for performing a CBC, serum chemistry profile, and urinalysis. Results obtained from the case history, physical
examination, and laboratory tests (CBC, serum chemistry profile, and urinalysis) are then used to determine additional diagnostic
needs. Regular diagnostic testing is a necessary part of the immediate point-of-care in older dogs and cats.
- Ferguson DC, Holson J, Caffall Z, et al: Influence of obesity on serum total and free thyroid hormone concentrations in cats.
ESVIM Meeting, Dublin, 2001; p. 117.
- Hoenig M: Interpretation of laboratory results in obese cats. Proceedings, 20th Annual Forum ACVIM, Dallas, 2002; p. 591.
- Willard M D, Tvedten H, Turnwald GH: Small Animal Clinical Diagnosis by Laboratory Methods, 3rd edition. Philadelphia, WB