Page 1210 - Veterinary Immunology, 10th Edition

VetBooks.ir Autoimmune Endocrine Disease

Although domestic animals develop autoimmune endocrine
diseases, they differ from humans insofar as these tend to be

targeted at single organs rather than involving multiple endocrine
glands. Occasionally a dog may experience two or more
autoimmune endocrine disorders simultaneously (autoimmune
polyglandular syndrome), usually affecting the thyroid and
adrenals, but this is uncommon.

Lymphocytic Thyroiditis

Dogs, humans, and chickens suffer from autoimmune thyroiditis. In
humans, this results from the production of autoantibodies against

thyroglobulin or thyroid peroxidase. These antibodies may also
react with triiodothyronine (T ) or thyroxin (T ). In dogs, many
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develop thyroiditis in the absence of these autoantibodies and cell-

mediated type 1 responses are responsible for thyroid destruction.
Several dog breeds are predisposed to thyroiditis, and relatives of
affected animals may have anti-thyroid antibodies although

clinically normal. A familial form of hypothyroidism has been
demonstrated in Beagles and Great Danes. Dogs from high-risk
breeds such as Dobermans tend to develop the disease when
young, whereas dogs from low-risk breeds tend to develop it when
older. Unfortunately, by the time the disease is diagnosed, the dog

may already have bred. Affected thyroids are infiltrated with
plasma cells and lymphocytes, and germinal center formation may
occur (Fig. 37.1). The invading lymphocytes probably cause

epithelial cell destruction through antibody-dependent cell-
mediated cytotoxicity (ADCC) and T cell cytotoxicity.

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