Lymphocytic Thyroiditis

Abstract

Lymphocytic thyroiditis is a common canine condition that can lead to functional hypothyroidism. It is associated with more than 50% of cases of canine hypothyroidism. Evidence in human beings and experimental situations suggests that it is a disease of defective immunoregulation, but specific investigation of the molecular pathogenesis of the naturally occurring disease in dogs has not yet been carried out. The condition is heritable in those breeds that have been studied, and progression to hypothyroidism, if it occurs, can be slow. Factors that influence the progression from subclinical thyroiditis to hypothyroidism in dogs are still to be identified, but excessive iodine intake is an important factor in other species.

Proliferative Responses to Canine Thyroglobulin of Peripheral Blood Mononuclear Cells from Hypothyroid Dogs

“…Therefore our results are not necessarily representative for all dog breeds with hypothyroidism. A variation in the prevalence of TgAA between different dogs breeds has been reported [9]. That finding suggests the heritability of lymphocytic thyroiditis.…”

“…Most studies on the pathogenesis of canine hypothyroidism have provided information on humoral immunity for development of diagnostic methods such as determination of serum TgAA, T3 autoantibody and T4 autoantibody levels [9]. The immunological and molecular pathogenesis of AITD in dogs has not been well characterized.…”

“…The proportion of hypothyroid dogs that have TgAA in serum is generally reported to be around 50% [2,9,10,24]. In a recent study, canine TgAA titers were found to decline during L-thyroxine treatment [8].…”

“…Thyroglobulin-specific antibodies have also been found in a high proportion of clinically diagnosed hypothyroid dogs [2,9,11,13]. Thyroperoxidase antibodies were not found in one study [23], but uncharacterized microsomal antibodies have been reported in others [10,15,25].…”

Do dogs develop autoimmune diabetes?

“…Dogs may develop similar conditions (e.g. lymphocytic thyroiditis [20]), and there is some evidence for an association between canine diabetes and hypothyroidism or Addison's disease [21]. The HLA associations of human type 1 diabetes were key to our understanding of the disease, and Catchpole and colleagues have produced the first evidence that diabetes in dogs is associated with dog leucocyte antigen (DLA) genes.…”