How many ways can the thyroid malfunction

From the Animal Endocrine Clinic Blog by Dr. Mark E. Peterson

Thyroid disease (i.e., hypothyroidism, hyperthyroidism, and   thyroid tumors) is common in dogs and cats. Dr. Ann Hohenhaus, an oncologist   and former colleague of mine at the Animal Medical Center in New   York City, wrote the following blog post on WebMD about 2 dogs and a cat with   thyroid disease that I thought was worth sharing.

The first case concerns a dog with thyroid cancer; the second case a hyperthyroid   cat who previously had intestinal lymphoma (a cancer); and the   third case of a dog with hypothyroidism.

How Many Ways   Can the Thyroid Malfunction?
By Ann Hohenhaus, DVM

The thyroid gland sits in the neck of dogs and cats, just below the voice   box, and controls metabolic functions. Most of the time, a routine physical   examination cannot detect the organ if it is normal.

Last week, my patient list ran the gamut of thyroid dysfunction. Here is a   sampling:

A Tail of Two Thyroids
Some days, strange coincidences happen in the waiting room. Today it was two   dogs, both with thyroid cancer. Although measuring 15 centimeters in length,   Beckey’s thyroid tumor had been surgically removed. The biopsy showed her   tumor trying to escape into the lymph vessels and she was waiting her turn   for chemotherapy, administered to halt the spread. Her treatment involves   intravenous administration of two different chemotherapy agents and Beckey so   far has sailed through the treatment with flying colors.

As Beckey was leaving the waiting room, Henry entered. A CT scan showed his   thyroid tumor had already spread to the lymph nodes in his neck, precluding   surgical removal. He was in for a check-up following completion of four   radiation therapy treatments. Careful measurement of his tumor with calipers   showed no increase in tumor size. The radiation treatment arrested tumor   growth but had given him a sore esophagus. I had warned the owners about this   type of side effect before we started treatment and told them to expect it to   start resolving about two weeks after he completed his treatment. Henry did   not disappoint us. Through telephone triage, we had already rearranged his   medications to make his throat less painful. Henry spends summer in the   country but in the fall he will come back to The AMC for measurement of the   tumor and a chest x-ray.

Old Patient, New Problem
Otra’s family was worried. This cute kitty had completed chemotherapy for   intestinal lymphoma about a year ago, but suddenly her weight plummeted. I   could see from the look on their faces they were sure the cancer was back.   Auscultation of Otra’s heart discovered a very elevated heart rate, prompting   a test of her thyroid levels. Overactive thyroid glands ramp up the cat’s   metabolism and they lose weight despite eating well, have a high heart rate,   and are very peppy. An abdominal ultrasound showed no evidence the lymphoma   had recurred and blood tests showed the thyroid was overactive. I sent   thyroid-suppressing medications home with the relieved family and planned to   reassess the thyroid hormone levels in two weeks.

Porterhouse to Pork Chop
Every time I saw Mango to follow up on a skin tumor that had been completely   removed via surgery, she had gained another pound. This 60-pound Portuguese   Water Dog should have weighed 50 pounds. The owners took her swimming, fed   her diet food from feeding toys, and still she gained two more pounds. During   an evaluation for a urinary tract infection, we noted her thyroid hormone   levels were borderline low. When we retested the levels three months later,   we confirmed diagnosis of hypothyroidism. Low thyroid function, the opposite   of Otra’s problem, can cause weight gain. Since she started treatment with   thyroid supplementation, Mango has lost nearly 6 pounds and gone from a   20-ounce porterhouse to a 4-ounce pork chop over the past few months!

There you have it, thyroid malfunction runs the gamut of disease: overactive,   underactive, and two different tumors, all in one tiny organ.