Thyroid dysfunction/ Thyroid testing

The thyroid gland secretes hormones (T4 and T3) which cause changes in many places including the hair and skin, muscles (including the heart), metabolism, red blood cells, sensitivity to hot and cold temperatures, and activity level. Cats most commonly develop hyperthyroidism, where the thyroid produces too much hormone and the cat may become hyperactive, become excessively hungry while still losing weight, have vomiting or diarrhea, and have increased risk of heart disease. Dogs most commonly develop hypothyroidism, where the thyroid produces too little hormone and the dog may become lethargic, easily gain weight, have a dry/ dull hair coat or other skin problems, and may seem mentally depressed. Testing for thyroid dysfunction can be done as an individual blood test, but is often run as part of a “geriatric blood work panel” since the thyroid disease can mimic other common diseases and can affect other organs. Treatment involves either decreasing or increasing the amount of thyroid hormone circulating in the body, and addressing any other secondary disease which is present (eg: heart disease, skin disease, obesity). After starting on medication, the thyroid level is typically rechecked monthly until the appropriate level has been reached, then every 6-12 months or sooner if the pet is having any other problems.