A 4 year old female Dalmatian was admitted to the Stange Memorial Clinic on Aug. 13, 1956, with the following history. The local veterinarian had examined the dog and found a small, hard non-fluctuating mass in the region of the thyroid. It was surmised that the dog was possibly suffering from a thyroid deficiency, precipitated by a tumor in the reg~on. The dog was placed on thyroid extract therapy but reacted violently by vomiting and exhibiting severe malaise.