CANINE AUTO-IMMUNE THYROID DISEASE
Antech Diagnostics
Update - important please read
Hound Alert Thyroid Function
Greyhounds and other sighthound breeds
(e.g. Afghan hound, saluki, borzoi, Scottish deerhound, whippet) typically have
basal levels of thyroid hormones at or even just below the lowest limits of the
adult normal reference ranges for most other breeds. This situation has been
largely overlooked, and is particularly noteworthy because of the
relatively large numbers of retired racing greyhounds that are adopted as pets.
The appropriate diagnosis of hypothyroidism in these dogs may be difficult to
make, especially during the immediate post-adoption period when the animal may
be in less than optimal health and is undergoing the stress of relocation and
adjustment to a pet home. However, clinically evident hypothyroidism also exists
in a subset of these dogs and is responsive to thyroid supplement.
The dosage of replacement levothyroxine
needed for hypothyroid sighthounds is typically about one-half of the
twice-daily dosage given to other dog breeds (i.e. 0.1 mg per 20 lbs. body
weight BID). Post-pill test levels should ideally be about or just below
mid-range at 4-6 hours after the morning medication.
The clinical situation is complicated further by the common assumption that the
pattern baldness ("bald thigh syndrome") commonly seen in adult greyhounds of
racing stock background is caused by hypothyroidism or some other endocrine
imbalance. The bald thigh presentation is a bilaterally symmetrical, nonpruritic
alopecia of the caudal and lateral aspects of the thighs. Recent study of a
large group of intact male and female racing greyhounds found no differences in
the concentrations of thyroid hormones or testosterone between affected bald and
unaffected control dogs, even though the racing females are routinely given
testosterone injections to suppress estrus. Thus, the bald thigh syndrome of
these dogs should not be attributed to hypothyroidism or testosterone levels.
References: Beale, KM, Bloomberg, MS, Van Gilder, J. Wolfson, BB. Keisling, K.
Correlation of racing and reproductive performance in greyhounds with response
to thyroid function testing. J Am Anim Hosp Assoc 196: 263-269, 1991;
Dodds, WJ. More information on
hematologic characteristics of greyhounds. J Am Vet Med Assoc 206: 1312, 1995;
Cowan, LA, Refsal, KR, Nachreiner, R., Schoning, P. Thyroid hormone and
testosterone concentrations in racing greyhounds with and without bald thigh
syndrome. J Vet Int Med 11(2):142, 1997.