Editors Corner...

Received a very nice letter from Dr. W. Jean Dodds, DVM which included some additional information relative to thyroid disease in dogs and the genetic aspects of the disease. Following is excerpted from her letter.

"Enclosed are some newer reference citations about thyroid disease in humans and dogs, including the genetic aspects of this disorder. Lymphocytic thyroiditis (called Hashimoto’s disease in humans) has clearly been shown to be an autoimmune disorder (Fisher, D.A. et al, Autoimmune thyroid disease: an expanding spectrum. Pediatr. Clin. North Am. 34: 907-918, 1987; Tomer, Y. And Davies, T.F. Infection, thyroid disease, and autoimmunity. Endocrine Rev. 14: 107-120., 1993; Utiger, R.D. The pathogenesis of autoimmune thyroid disease. N. Engl. J. Med. 325: 278-279, 1991; Gosselin, S.J. et al, Autoimmune lymphocytic thyroiditis in dogs. Vet. Immunol Immunopathol 3: 185-201, 1982). Also, the predisposition to autoimmune disorders including autoimmune thyroiditis is genetically determined in humans, dogs, and all other species studied to date (Carson, D.A. Genetic factors in the etiology and pathogenesis of autoimmunity. FASEB J. 6: 2800-2805, 1992). As recently stated by Dr. Ray Nachreiner of Michigan State University for the new OFA Thyroid Registry -- ‘Autoimmune thyroiditis is heritable’.

The original clinical research establishing the genetic basis of canine thyroiditis was performed on beagles, and was followed by studies of this disorder in the Great Dane and Borzoi breeds (Conaway, DH et al. Clinical features of primary progressive, familial thyroiditis in a colony of borzoi dogs. Vet. Pathol. 22: 439-446, 1985; Haines, K.M. et al. Survey of thyroglobulin autoantibodies in dogs. Am. J. Vet. Res. 45: 1493-1497, 1984). Since then, I and others like Dr. Nachreiner have studied the vertical transmission (i.e. heritability) of thyroid disease in families of Old English Sheepdogs, Shih Tzu, Weimaraners, Akitas, Golden Retrievers, Vizslas, Scottish Terriers, and Kerry Blue Terriers. As far as the mastiff breeds are concerned, accumulated data on Neopolitan, Tibetan, and English Mastiffs indicates a strong familial pattern of thyroid disease. I personally do not have enough data on the Bullmastiff to make this observations, but would expect from what other colleagues have indicated, that they also have a similar pattern of thyroid disease leading to overt hypothyroidism.

Idiopathic thyroid atrophy accounts for only a small percentage of cases of thyroid disease in humans and animals. This form of thyroid disease also has been shown to be caused by autoimmune destructions of the gland (Wilkin, T. J. Receptor autoimmunity in endocrine disorders. N. Engl. J. Med. 323: 1318-1324, 1990).

I hope this information is helpful and clarifies some of the important issues about thyroid disease facing purebred dogs today".

(We certainly appreciate the input from Dr. Dodds, who, for those of you who do not know her, is "universally recognized as one of the preeminent authorities on blood diseases in small animals, from acquired autoimmune disease to inherited bleeding disorders like von Willebrand’s disease". (as quoted from Veterinary Practice STAFF which featured a multi-part report by Dr. Dodds on genetically based immune disorders). I have available a number of the articles mentioned by Dr. Dodds, as well as others on the subject if anyone would like copies).