Idiosyncrasies in greyhounds that can affect their medical care - Veterinary Medicine
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Idiosyncrasies in greyhounds that can affect their medical care
These athletes have been bred for speed and an even temper. But some irregularities in greyhounds will affect how to clinically assess and treat these dogs. Make sure you're prepared for the next greyhound that visits your practice.


VETERINARY MEDICINE


Thyroid hormone concentrations

Greyhounds have lower thyroid hormone concentrations (total thyroxine [T4] and free T4 by equilibrium dialysis) than other breeds (Table 1).7 The clinical relevance of this is controversial in veterinary medicine. Some veterinarians think that most greyhounds are hypothyroid and should be supplemented with levothyroxine, whereas others think that the lower concentrations are normal for the breed.

One greyhound adoption program suggests that greyhounds that show shyness or anxiety receive thyroid supplementation regardless of thyroid hormone concentrations.8 I disagree with this and think greyhounds are often oversupplemented with thyroid hormone replacement medications. Greyhounds normally show many outward signs that might be confused with signs of hypothyroidism. Many greyhounds are inactive and cold-intolerant and have caudal thigh alopecia. These signs may not be a result of hypothyroidism. The thigh alopecia is referred to as bald thighs syndrome and is not consistently thyroid hormone-responsive.9

Hypothyroidism should only be diagnosed in a greyhound based on the results of a full thyroid profile (total T4 concentration, free T4 concentration by equilibrium dialysis, total triiodothyronine [T3] and free T3 concentrations, and a thyroid-stimulating hormone response test) and supporting clinical signs. (Total T3 and free T3 concentrations in greyhounds are similar to those in other breeds.) The Diagnostic Center for Population and Animal Health at Michigan State University** performs a complete thyroid panel and can provide interpretation by veterinary endocrinologists who have extensive knowledge of a greyhound's normal thyroid hormone concentrations.

Other idiosyncrasies

Greyhounds have lower globulin concentrations and higher sodium, chloride, and bilirubin concentrations than other breeds (Table 1), although these findings are rarely misinterpreted or clinically relevant.3

CARDIOLOGIC IDIOSYNCRASIES

Greyhounds may have mildly enlarged hearts and mild heart murmurs that can occasionally be considered normal. The murmur is known as a physiologic flow murmur and is considered idiopathic but most likely relates to turbulent blood flow associated with a high stroke volume.10,11 The physiologic flow murmur can be characterized as systolic (not holosystolic), loudest over the left base, and low intensity (grade III or less)10,11 and must be distinguished from murmurs due to cardiac diseases. Mild generalized heart enlargement is also a common finding in many normal greyhounds, even many years after retirement.

Echocardiographic idiosyncrasies noted in greyhounds include enlarged left ventricular cavity dimensions, increased left ventricular and septal wall thickness, and increased systolic time intervals when compared with nongreyhounds. These differences were significant despite corrections for body surface area and body weight.12 Greyhounds are also known to have significantly higher mean arterial pressures than nongreyhounds (118 mm Hg vs. 98 mm Hg).13

DERMATOLOGIC IDIOSYNCRASIES

Alabama rot

Idiopathic cutaneous and renal glomerular disease, also known as Alabama rot, is a rare disease seen more frequently in greyhounds than in other breeds.14-16 It is thought to be caused by Escherichia coli 0157:H7 toxin.14 The first clinical signs noted are inflamed and painful cutaneous swellings that may crust and progress to slow healing ulcers ranging from a few millimeters to several centimeters in length. The most commonly affected sites include the hocks, stifles, or medial thighs. In rare cases lesions may be noted on the forelimbs, thorax, or ventral abdomen. General malaise and inappetence is often associated with this period. Renal disease occurs in 25% of cases and may occur up to 10 days after the onset of signs.


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Source: VETERINARY MEDICINE,
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