By Susanne Stack, DVM
When your veterinarian sends your greyhounds blood to a lab he is most commonly asking the lab to run a CBC (Complete Blood Count). This common analysis covers these items:
On ocassion the veterinarian may also ask for additional information. Some of the more common tests are
If you dont understand what your veterinarian has ordered, ask.
Greyhound bloodwork has enough differences from other dog bloodwork to sometimes make it deceivingly normal or abnormal if one isnt familiar with these differences. The salient differences are discussed below.
Greyhounds have significantly more red blood cells than other breeds. This elevates parameters for RBC, hemoglobin, and PCV/HCT, and is the reason greyhounds are so desirable as blood donors. Most veterinarians are aware of this difference.
Other greyhound CBC changes are less well known. The greyhounds normally low WBC has caused more than one healthy greyhound to undergo a bone marrow biopsy in search of cancer or some other cause of the low WBC.
Likewise, greyhound platelet numbers are lower on average than other breeds, which might be mistakenly interpreted as a problem. It is thought that greyhound WBCs, platelets, and total protein may be lower to physiologically make room in the bloodstream for the increased red cell load.
T.P. & Globulin
Greyhound total proteins tend to run on the low end of normal T.P.s in the 5.0s and 6.0s are the norm. While the albumin fraction of T.P. is the same as other dogs, the globulin component is lower.
Greyhound creatinines run higher than other breeds as a function of their large lean muscle mass. A study at the Auburn University College of Veterinary Medicine found that 80% of retired greyhounds they sampled had creatinine values above the standard reference range for other dogs. As a lone finding, an elevated creatinine is not indicative of impending kidney failure. If the BUN and urinalysis are normal, so is the elevated creatinine.
These figures are from a University of Florida study of thyroid function in 221 greyhounds 97 racers, 99 broods, and 25 studs so it included both racers and retired. While greyhound thyroid levels are a whole chapter unto themselves, a good rule of thumb is that greyhound T4s run about half that of other breeds.
And lastly, the good news greyhound urinalysis is the same as other breeds. It is normal for males to have small to moderate amounts of bilirubin in the urine.
Sources: M.R. Herron, DVM, ACVS, Clinical Pathology of the Racing Greyhound , 1991. C. Guillermo Couto, DVM, ACVIM, Managing Thrombocytopenia in Dogs & Cats, Veterinary Medicine, May 1999. J.Steiss, DVM, W. Brewer, DVM, E.Welles, DVM, J. Wright, DVM, Hematologic & Serum Biochemical Reference Values in Retired Greyhounds, Compendium on Continuing Education, March 2000. M. Bloomberg, DVM, MS, Thyroid Function of the Racing Greyhound, University of Florida, 1987. D. Bruyette, DVM, ACVIM, Veterinary Information Network, 2001.