How To Diagnose Feline Hyperthyroidism

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THE BREGMAN VETERINARY GROUP

www.BregmanVetGroup.com

Hyperthyroidism, and known as “hyperthyroid disease,” occurs when the thyroid gland enlarges, and starts producing excess amounts of thyroid hormone (thyrotoxicosis). This is usually caused by a benign tumor on one or both of the thyroid glands’ lobes. Although thyroid tumors can be cancerous, the chances are only 2% to 5% of malignancy.

Not all symptoms will be seen in every cat, but any one or two of them should be a strong indication that a veterinary examination is indicated. Some of the symptoms that may be present are increased appetite, unexplained weight loss and loss of muscle mass, irritability, frequent vomiting, diarrhea, excessive thirst, weakness and lethargy.

In order for this to be diagnosed, the veterinarian will palpate the cats’ neck area and may feel the enlarged gland. Since hyperthyroidism can mimic the symptoms of other diseases, such as chronic kidney failure or liver disease, a blood panel will usually show the “big picture,” when combined with a thyroid-specific test, usually the T-4, which will show thyroid levels. Elevated levels of T4 will usually indicate the presence of this disease.

There are three standard treatment options available. Each offers a strong possibility of returning the thyroid gland to normal function.

• Anti-Thyroid medication (Tapazole) is an oral medication that is given twice daily. Many cats do well on this medicine, however, it has to be given to the cat every day for the rest of its life. It also requires regular blood tests to monitor hormone levels, so dosage can be regulated. The positive is that this is relatively inexpensive. As for the disadvantages, there could be some side effects that include vomiting, fever, anemia, lethargy and anorexia. Also, frequent veterinary follow up is needed.

• Surgery can also be an effective treatment. Surgery is most often indicated when only one thyroid lobe is involved. An advantage of surgery is that it eliminates the need for long-term medication. Some disadvantages include possible damage to the adjacent parathyroid gland, hazards of anesthesia and if only one lobe is removed, a recurrence is possible.

• The last treatment, which has become the “Gold Standard,” is Radioiodine Treatment. A single injection of radioactive iodine (I-131) is given under the skin (similar to a routine vaccination). The iodine is selectively taken up by the thyroid tissue and destroys it. No harm is done to normal tissue. The cat must remain in the vet hospital for an average of 5-7 days until his radioactive levels are acceptable. One major advantage is that it provides a permanent cure in 95% of cases. A disadvantage is that the initial cost is higher, but it equal to about 18-24 months of care with the oral medication.

If your cat is showing signs of this disease, please call us immediately so we can schedule an appointment.