Dear Doctor - February 2016
Blood work: How often is best?
Q I have an eight-year-old cat who I rescued from a shelter as a kitten. I take Daisy to our local veterinarian once a year for a health examination. During our last visit, the veterinarian recommended that we run blood work every year. Is this really necessary for my cat, who is overall healthy? If so, can you explain the advantages of looking at blood work every year?
A Dear Elizabeth: The American Veterinary Medical Association states on their website that, “geriatric pets should have semi-annual veterinary visits instead of annual visits so signs of illness or other problems can be detected early and treated. Senior pet exams are similar to those for younger pets, but are more in depth, and may include dental care, possible blood work, and specific checks for physical signs of diseases that are more likely in older pets.”
Take note of the wording, “POSSIBLE blood work.” Annual blood screening has pros and cons. Some diseases — when detected early — may be more effectively managed. The progression of kidney disease, for example, may be slowed when a special diet is started early in the course of disease.
But there are also cons to routine screening. Cost is most obvious as screening of blood and urine can cost $200 or more. Less obvious is the potential harm of false positive results and subsequent costly or invasive procedures. Investigation of elevated liver enzymes, for example, could run over $1,000 and involve biopsy. Benign causes for liver enzyme elevation are common and many of these patients don’t benefit from the additional testing. However, once an abnormality is discovered, it may be difficult to ignore the finding.
It is not always clear if the benefits of screening outweigh the risks of the screening procedure itself, follow-up diagnostic tests and treatments. Evidence in humans suggests that in groups at low risk, we are creating more problems than benefits with early screening.
You should talk over the pros and cons of routine screening with your vet. I try to individualize my recommendations based upon my evaluation of the pet and the owner’s wishes.
Michael Stone DVM, ACVIM
Clinical Assistant Professor
Cummings School of Veterinary
Medicine at Tufts University