The Detection of Auto-Immune Thyroiditis in Dogs

Abstract

A micro Ouchterlony gel diffusion test was adapted for detecting auto-immune thyroiditis. The Ouchterlony test was standardized by testing crude thyroid extract against antiserum from an immunized rabbit. The rabbit was sensitized IV by three seperate injections of the crude thyroid extract and finally fully immunized with an injection IM by a 1:1 solution of crude thyroid extract and incomplete Freund's adjuvant. A clinical sample of dog serums of low T4 and normal T3 levels which were suspect of thyroiditis and were close to being Hypothyroid were tested by the Ouchterlony test. No lines were produced when the antiserum from 16 dogs and crude extract were in the gel diffusion wells. The negative results indicate that the dogs of clinical interest did not have thyroiditis and also that there exists a second mechanism for Hypothyroid development other than thyroiditis. The validity of the results were not checked by actually testing a thyroiditis dog but by assuming values for the chances that the test worked; the probability that the test gave negative results when all dogs tested were actually thyroiditis turned out to be low(P=.5,.01% chance of wrong results and p=.2,4.4% chance of wrong results). Some tests and further research is suggested and should be directed toward quantifying the thyroiditis test by inducing thyroiditis in a dog and using that as a model of the disease. Also a more sensitive test such as a radioassay method (11) should be employed.