The following article by Dr. Jeff Grogner, DVM, is reprinted with permission from the American Kennel Club Gazette. We enourage you to share it with your veterinarian.
WHAT MAKES A GREYHOUND DIFFERENT?
Over the centuries, the Greyhound has been singled out as a superior racing breed. In their quest to produce the fastest dogs, breeders have selected for traits that set Greyhounds apart from other dogs. The result was the fastest of the canines, but also other characteristics that make this sight hound different from other dogs. For instance, Greyhound's scores on blood tests do not fall within established normal canine ranges, they experience their own unique medical conditions, and they handle anesthetics unlike other breeds of dogs. Their idiosyncrasies must be recognized when Greyhounds are in need of medical care.
Another obvious dissimilarity between Greyhounds and other breeds is that they have higher quantities of red blood cells. As athletes, they need these to carry higher oxygen loads to their working muscles. One way to measure red blood cells is with a packed cell volume (PCV) - a tiny blood sample is spun in a tube to separate the cells from serum. The quantity of red blood cells that settle to the bottom is measured as a percentage of the total volume.
Though the normal canine range for a PCV is 37 to 55, Greyhounds typically have levels between 41 and 64. A PCV of 38 is normal for any other dog, whereas a Greyhound with this result is anemic.
Greyhounds are well known for their low thyroid hormone (T4) levels. They also frequently have clinical signs such as cold intolerance, inactivity, and hair thinning that can be wrongly confused with hypothyroidism. For this reason, hypothyroidism is often misdiagnosed in Greyhounds. A full thyroid panel, not just the T4 value coupled with clinical signs, is required to determine if a Greyhound has this disease.
Because Greyhounds are so well muscled, they produce a lot of cretonne - the breakdown product of protein. Normal canine levels peak at 1 milligram per deciliter whereas healthy Greyhounds have values up to 1.6. Because cretonne levels also rise with kidney disease, not knowing this breed's reference range can lead to a misdiagnosis of kidney failure.
A Greyhound's heart is unique, again due to the breed's athletic nature. It is larger on radiographs than the heart of a dog of similar body stature. Some Greyhounds also have a murmur, which is caused by the massive amount of blood pumped and not by heart malfunction.
OTHER UNIQUE CHARACTERISTICS
Greyhounds have some unusual skin disorders. Ventral comedo syndrome affects many Greyhounds on their chests, where their skin makes contact with the ground. Trauma to the hair shafts blocks hair follicles, causing the formation of a comedo (blackhead). There is no specific treatment for this condition, though shampooing with benzoyl peroxide products can help.
Bald thighs syndrome is a non-itchy, non-inflammatory alopecic (hair loss) condition that afflicts the backsides of the hind legs of Greyhounds. There is no known cause and no specific treatment. It often resolves within a few months of retirement from racing. It sometimes responds to thyroid hormone supplementation.
Greyhounds have a reputation for having difficulty under anesthetics. The sedative acepromazine can be used, but only at a low dose. Greyhounds are extra sensitive to acepromazine's effects. Complete recovery from thiobarbiturate anesthetics can take up to eight hours, whereas a non-Greyhound takes only one or two hours to clear the drug. This is due to the poor metabolism of the anesthetic by the liver. Thankfully, there are a number of anesthetics available today that are much safer for this breed - isoflurane is the best example.
As more and more retired racing Greyhounds are placed in family homes (about 18,000 annually), more idiosyncrasies are sure to come to light. Understanding these unique differences will improve both diagnostic testing and treatment regimes for members of this elite breed.