Review of the litterature and an attempt to evaluate intake levels of iodine and selenium in dogs with and without lymphocytic thyroiditis

Abstract: The prime aim of this thesis was to investigate whether high or low iodine intake during certain periods of life was, or was not a strong risk factor for the development of canine lymphocytic thyroiditis (CLT). And secondly, if a high or low selenium intake in a combination with high or low iodine intake also may have an influence on that risk factor. To investigate this, a dietary questionnaire was sent out to dog owners. The dogs were selected from an ongoing genetic study of CLT. The questions investigated brand and type of feed during different life stages (puppy, junior and adult) and also if there were any use of dietary supplements. The thesis was also extended with a substantial literature review about the relationship between iodine, selenium (both excess and deficiency) and the thyroid hormone metabolism.In some parts of the world, humans suffer from an autoimmune thyroid disease called Hashimoto’s as a result of high iodine intake. Previous studies have indicated that high iodine intake could also be linked to canine lymphocyticthyroiditis, the dogs equivalent to Hashimoto´s disease. The result of the questionnaire showed that most dogs have had high iodine feeds during some period in life. Due to lack of data regarding selenium content in feeds, these effects could not be evaluated. Any distinct connection between iodine intake and development of canine lymphocytic thyroiditis could not be proven.