Thyroid Issues In Dogs and Cats
Causes of Canine Hypothyroidism
Symptoms of Canine Hypothyroidism
Weight gain without increase in appetite or calorie intake
Skin issues: Discoloration, dry, or thickening of the skin
Low tolerance for the cold
Excess shedding or scaling
Changes in coat quality: dull, dry or brittle
Signs of depression or listlessness
loss or thinning of the fur
- Noticeable changes in behavior
Slowed heart rate
- Skin and ear infections
How is hypothyroidism diagnosed?
How to treat hypothyroidism?
Causes of Feline Hyperthyroidism
Feline hyperthyroidism is the most commonly diagnosed endocrine disorder in domestic cats, especially in middle-age and older cats. In almost all cases, Feline hyperthyroidism is caused by a benign (non-cancerous) tumor or adenoma on the thyroid gland that causes overproduction of the hormone thyroxine.
The thyroid gland is butterfly-shaped and located at the base of the throat, with one lobe on each side of the cat’s trachea. Overactivity in thyroxine production can cause an abnormal metabolic rate that can negatively affect a cats organs. In addition, to high blood pressure issues, it is often linked to kidney disease. Below are some typical symptoms to be aware of.
Symptoms Of Hyperthyroidism In Cats:
Significant weight loss (often accompanied by a voracious appetite)
Overeating. Though a loss of appetite is also possible
More water intake and increased urination
- Increased heart rate
Changes in behavior: Hyperactive, irritable, nervousness, sometimes aggression
- Deteriorated coat, changes in grooming habits
- Muscle loss. Can also affect heart.
Gets out of breath unusually quickly
- Enlarged growth on thyroid noticeable
How is hyperthyroidism diagnosed?
Diagnosis of hyperthyroidism is based on a combination of clinical signs and bloodwork. Weight loss, muscle wasting, heart disease and a thyroid nodule are all indicators to a veterinarian that a cat may have hyperthyroidism. Definitive diagnosis is based on bloodwork, specifically an elevated Thyroxine level. In most cases feline hyperthyroidism can be diagnosed with a single blood test that measures the total thyroxine (T4) concentration.
How To Treat Feline Hyperthyroidism?
Once your cat has been diagnosed with having hyperthyroidism, your veterinarian will consider the factors involved in the case. This would include how elevated the (T4) level is, the cat’s overall heath profile, medical history, and age. There are various options for treating hyperthyroidism, and your vet will discuss them with you and determine the best course of action for treatment.
Feline hyperthyroidism can be treated with an oral medication that contains methimazole. This medication can be given life-long or to stabilize the cat before other treatment options, such as radioactive iodine therapy or surgery. Felimazole Coated Tablets (methimazole), is the FDA-approved drug to treat hyperthyroidism in cats. The drug is typically given by mouth every 12 hours. Your veterinarian will adjust the dose, as necessary, based on the results of your cat’s blood tests and response to treatment.
Surgery is another common treatment for feline hyperthyroidism. It involves the removal of the thyroid gland (thyroidectomy). Your veterinarian will review the case and discuss the options with you. There are two approaches to surgically removing the gland. Sometimes only one of the lobes is affected, so only that lobe need be removed, however data suggests that the other lobe will become affected in 1-2 years, so often the approach is to remove both lobes. Surgery also introduces the concept of anesthesia which may not be viable for an older cat or one with underlying conditions.
Radioactive iodine therapy for hyperthyroidism
Radioactive iodine therapy (I-131) is widely considered the safest and most effective treatment. It has few side-effects and is generally a 1-time treatment in 95% of cats diagnosed with hyperthyroidism. The thyroid stores iodine, and small amounts of radioactivity can stop the overactive gland from producing too much thyroid hormone.
The amounts of radioactivity are too small to affect the rest of your cat’s body, and it is eventually passed out of the body via urine. No general anesthetic is needed, and medication is not required long-term.
Diet control for hyperthyroidism
Some studies have shown that it is possible to treat feline hyperthyroidism with an iodine-restricted diet. Without iodine, the thyroid gland is unable to make any hormones. The affected cat would need to eat a prescription diet with strictly controlled iodine levels. This diet is very strict however, and in order to be effective, the cat must not consume any other food or liquid apart from water. This would be a very challenging diet to maintain if the cat was in a multi-cat environment, or spends time outdoors. It would be nearly impossible to ensure that the cat is not eating any unregulated food and even the smallest amount will allow hormone production to happen. Your veterinarian can provide more information and work with you to decide if this avenue or any of the other treatments would be appropriate for your cat.
Complications of Hyperthyroidism in Cats