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Greyhound Bloodwork
By Suzanne Stack, DVM
This article was reprinted, with permission, from the website www.greythealth.com. Dr. Stack has many years’ experience with racing greyhounds and resides in Arizona.
(Excerpt from Summer 2006 issue of GCNM News)

Greyhound bloodwork has enough differences from "other dog" bloodwork to sometimes make it deceivingly "normal" or "abnormal" if one isn't familiar with these differences. The salient differences are discussed below.

CBC = Complete Blood Count
RBC = Red Blood Cells
Hgb = Hemoglobin
PCV / HCT = Packed Cell Volume / Hematocrit
WBC = White Blood Cells
Platelets

 

NORMAL VALUES FOR:

 

Greyhounds Other Dogs
RBC: 7.4 - 9.0 5.5 - 8.5
Hgb: 19.0 - 21.5 12.0 - 18.0
PCV: 55 - 65 37 - 55

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. Never accept a diagnosis of polycythemia - a once-in-a-lifetime-rare diagnosis of pathologic red cell overproduction - in a greyhound.

Conversely, never interpret a greyhound PCV in the 30's - low 40's as being normal just because it is for other dogs. A greyhound with a PCV in the 30's - low 40's is an anemic greyhound. Here in Arizona, a greyhound PCV < 50 is a red flag to check for Ehrlichia.

WBC
Greyhound: 3.5 - 6.5
Other dog: 6.0 - 17.0

Other greyhound CBC changes are less well known. The greyhound's 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."

Platelets
Greyhound: 80,000 - 200,000
Other dog: 150,000 - 400,000

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.

Confounding these normally low WBC and platelet numbers is the fact that Ehrlichia, a common blood parasite of greyhounds, can lower WBC and platelet counts. So if there is any doubt as to whether the WBC / platelet counts are normal, an Ehrlichia titer is always in order. The other classic changes with Ehrlichia are lowered PCV and elevated globulin and total protein. But bear in mind that every greyhound will not have every change, and Ehrlichia greyhounds can have normal CBCs.

Chem Panel
T.P. = Total Protein
Globulin
Creatinine
T4

 

NORMAL VALUES FOR:

 

T.P. Globulin
Greyhound: 4.5 - 6.2 2.1 - 3.2
Other dog: 5.4 - 7.8 2.8 - 4.2

Greyhound total proteins tend to run on the low end of normal - T.P.s in the 5.0's and 6.0's are the norm. While the albumin fraction of T.P. is the same as other dogs, the globulin component is lower.

Creatinine
Greyhounds: .8 - 1.6
Other dogs: .0 - 1.0

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 up to 1.6 times as high as the top of 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.

T4
Greyhounds: .5 - 3.6 (mean 1.47+/- .63)
Other dogs: 1.52 - 3.60

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.

Urinalysis
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, Enwalls, 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.

 


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