Just Ask the Expert: Are thyroidectomies still an option for cats with hyperthyroidism?

Dr. Newton welcomes surgery questions from veterinarians and veterinary technicians.

Click here to submit your question, or send an e-mail to vm@advanstar.com with the subject line "Surgery questions."

What is your opinion about thyroidectomies for cats with hyperthyroidism, and why are most veterinarians reluctant to perform this procedure, which seems no more difficult than performing an ovariohysterectomy and provides immediate patient response?

Jenifer Newton, DVM, MS, DACVS

A. Thyroidectomy is no longer my treatment of choice for cats with hyperthyroidism for several reasons.

The most obvious reason is that by removing the visible thyroid tissue at the level of the gland, you may inadvertently remove all of the parathyroid tissue. This would cause hypocalcemia and possible seizures in the patient. This alone makes the surgical technique more complicated than a routine ovariohysterectomy. By removing the glands, you also potentially induce hypothyroidism, necessitating thyroid hormone supplementation.

Finally, cats may have ectopic thyroid tissue further down the neck and even into the thoracic cavity. Only radioactive iodine will effectively target all of the abnormal thyroid tissue, so radioactive iodine therapy is my treatment of choice for hyperthyroid cats.

SUGGESTED READING

1. Feldman EC, Nelson RW. Feline hyperthyroidism (thyrotoxicosis). In: Canine and feline endocrinology and reproduction. 3rd ed. Philadelphia, Pa: Saunders, 2004;152-218.

2. Ehrhart N. Thyroid. In: Slatter D, ed. Textbook of small animal surgery. 3rd ed. Philadelphia, Pa: Saunders, 2003;1700-1710.

Jenifer Newton, DVM, MS, DACVS

Saint Francis Veterinary Specialists

625 Dekalb Industrial Way, Suite 500

Decatur, GA 30033