January is National Thyroid Awareness Month. Did you know that dogs and cats develop thyroid disease? Older cats commonly develop hyperthyroid disease which is due to an overactive thyroid gland. Dogs commonly develop hypothyroid disease which is due to an underactive thyroid gland. This week I will discuss hyperthyroid disease in cats and next week I will discuss hypothyroid disease in dogs.
The thyroid gland is a paired endocrine (produces hormones) organ that is located in the neck. The thyroid secretes hormones that help regulate the body’s metabolism. Hyperthyroidism occurs when this gland is secreting too much of these hormones causing the body’s metabolism is increased. Pure breed cats, especially Siamese and Himalayans, are more likely to develop this condition. Hyperthyroid disease is common in cats over 10 years of age, so senior blood work screening for this disease is important.
The hallmark sign seen with hyperthyroidism is weight loss despite a ferocious appetite. Other symptoms include increased heart rate, hyperactivity, vomiting, and diarrhea. If the disease progresses without proper treatment cats will develop secondary heart and kidney problems. Diagnosis is made from blood work, physical exam and symptoms. A normal thyroid gland cannot be felt with a finger while an overactive gland can be easily felt.
1. Oral medication:
Pro: The medication is relatively inexpensive.
Con: Medication requires daily pilling for the rest of the cat’s life. It can take several weeks before any response to treatment is noticed. A small percentage of cats can develop skin reactions or liver disease and then the medication must be discontinued. Blood work should be done every six months to monitor for liver disease which increases the cost of this treatment.
Pro: The enlarged thyroid gland can be surgically removed. Once the affect thyroid gland is removed the cat will immediately improve.
Con: This is an expensive procedure. Since this is a paired gland, the other side is left to continue functioning as normal; however, that gland can develop the same problem and need to be removed at a later date.
3. Radioactive iodine: This procedure involves injecting radioactive iodine intravenously which causes the overactive cells to die.
Pro: This treatment has a 98% cure rate with a low chance of reoccurrence.
Con: This is the most expensive treatment for thyroid disease. The cat has to stay isolated in the hospital for about one week because it is radioactive. This procedure is usually not performed by your veterinarian and must be referred to a specialty clinic.
4. Diet: Science Diet has developed a diet called y/d that has proven effective in the treatment of some cats with hyperthyroid disease.
Pro: This is the easiest of all treatments and probably the cheapest.
Con: If the cat eats any other diet, treat or food the diet will not effectively treat this thyroid disease. This treatment usually doesn’t work well for individuals that have multiple cats in the household.
It is very important to detect hyperthyroid disease early before heart and kidney disease develop because some cats with these problems are not candidates for surgery or radioactive iodine treatment. These cats can be managed with medication or diet.