Hypothyroidism (= insufficient production of thyroid hormone by the thyroid gland) is one of the most common hormonal dysfunctions in dogs. Most cases of hypothyroidism in dogs are caused by an autoimmune disease, which is called lymphocytic thyroiditis. The disease progresses gradually over several years. Affected dogs become lethargic and their willingness to perform is decreased. Often a "sad facial expression" is noted, which is due to an increased deposition of water and mucopolysaccharides into the subcutaneous connective tissue. Affected dogs gain weight, even if they don't get more food. The coat becomes dull, brittle, and flaky (dry or oily). The hair structure becomes thinner and tends to felt. Hair loss is common, Hovawarts often lose their hair at the tail giving the impression of an "Afghan tail". Additional neuromuscular or heart/circulation symptoms may occur. Symptoms regarding sexual behaviour (loss of libido, weak or absent heat) and the digestive tract may also occur. Together with the University of Uppsala, Sweden, we would like to further investigate the genetic risk factors for lymphocytic thyroiditis in the Hovawart. Our aim is the development of a genetic test, which is specifically suited for the Hovawart breed. For the research we need EDTA blood samples from affected dogs, ideally together with their parents and siblings. We therefore ask breeders and owners to donate samples for our research.