October 29, 2018

Study on Familial Thyroiditis in a Borzoi Colony

Lymphocytic Thyroiditis is an autoimmune disease found in dogs similar to the human Hashimoto's disease. While well documented in groups of laboratory beagles, recent studies have shown it's connection to hypothyroidism in dogs.

A study on 16 borzoi dogs, 10 inbred and 6 related, was done over the course of 6 years in Buckley, MI. All dogs were given the standard vaccinations for leptospirosis, hepatitis, and parvovirus. Beginning at birth, blood samples were taken from each dog monthly to analyze their Serum triiodothyronine and thyroxine (main two hormones produced thyroid gland). This was done consistently over about two years time at monthly intervals. In addition to this every six months thyroid tests were done on the dogs and compared to their control. At two years of age, biopsies on the 10 dogs and their parents were done by removing a small piece of either the right or left thyroid lobe.

The resulting data concludes that while significant skin lesions were found on 2 out of the ten puppies, and thyroid glands which could be classified as degenerative-non-inflammatory, inflammatory, and endstage. The thyroxine levels of affected dogs were far lower than normal (control group used), while triiodothyronine levels in the experimental dogs were much high than normal. However, looking at the thyroid gland reserve showed no significant differences between the experiment and control groups. Comparing these results to common trials done for hypothyroidism showed that it seems as if all pups from the experimental litter were in various stages of hypothyroidism. This evidence helps to conclude the inefficiency of this as a method of analyzing and searching for early signs of hypothyroidism. While signs of thyroid gland degeneration is present, many follicles still remain and due to the fact that "One report states that normal thyroid function and response may be maintained with as little as 25 to 30% of the healthy thyroid follicles present" it can be near impossible to gauge if hypothyroidism is occurring until in late stages of the condition.

Conaway, D. H., Padgett, G. A., Bunton, T. E., Nachreiner, R. & Hauptman, J. Clinical and Histological Features of Primary Progressive, Familial Thyroiditis in a Colony of Borzoi Dogs. Veterinary Pathology 22, 439–446 (1985).

Access full article at : http://journals.sagepub.com/doi/pdf/10.1177/030098588502200502 

Reviewed by Sydnie Dillon, 10/29/2018