Feline hyperthyroidism is a common disease in older cats, with most cats developing the disease after the age of 10 years. The symptoms associated with this disorder can range from mild to dramatic and may prove fatal without treatment. Thankfully, it is a treatable disease and most cats can recover from it completely.
What is feline hyperthyroidism?
Hyperthyroidism is a hormonal disease that affects the thyroid glands. It is characterized by the overproduction of the thyroid hormone known as T4. This hormone regulates the metabolism of cells in the cat’s body. If there is too much at one time, most of the body’s organs become overstimulated, resulting in unnecessary or even fatal stress.
Signs and symptoms of Feline Hyperthyroidism
There are different clinical signs associated with feline hyperthyroidism. Initially, the symptoms will be subtle enough to escape notice but as the disease worsens, the symptoms become harder to ignore. Some of the most common signs of the disease include:
- weight loss in spite of excessive appetite
- excessive thirst followed by excessive urinating
- increased vocalization
- attitude changes (an otherwise mild-mannered cat becomes easily upset or aggressive)
- fast heart rate even at rest
- hair loss
- refusal to groom
- diarrhea
- weakness
- depression
- vomiting
Majority of cats exhibit some of these symptoms but there is a small percentage of pets that may have apathetic symptoms. This group may only appear lethargic and refuse to eat but may not exhibit any other clinical signs.
Diagnosis of Feline Hyperthyroidism
A veterinarian will perform a physical checkup of your pet to feel for an enlargement of the thyroid glands in front of the neck. Blood tests will also be performed to check for levels of T4 in the blood. Some laboratory tests may also be helpful, since hyperthyroidism affects other organs in the body. Other tests will help rule out any possible causes or disease that may also be present.
Treatment of Feline Hyperthyroidism
Treatment for cat hyperthyroidism usually consists of drug therapy, radioactive iodine therapy and/or surgical thyroidectomy. Drug therapy usually consists of methimazole or carbimazole. Both medications are administered orally and work to reduce the production of T4. Methimazole is usually given twice a day while carbimazole, with its slow-release formula, is only given once a day. Drug therapy is usually recommended for both long-term and short-term treatment. It is usually administered throughout the cat’s life to regulate the function of the thyroids. Both drugs are considered safe, with minimal side effects.
Radioactive iodine therapy consists of a dose of iodine given through an injection. The radiation kills the affected thyroid tissue without damaging the tissues or glands nearby. The risk is low for the cat but the therapy involves careful administration due to the use of radioactive material. It is considered a cure, however and can treat abnormal tissues in the thyroid successfully.
Surgical thyroidectomy is another treatment approach for feline hyperthyroidism. It consists of the removal of the abnormal thyroid tissues in order to prevent them from producing excess hormones. It is considered a long-term solution and even a permanent cure when done correctly and is actually a popular option among pet owners. Surgery does have its complications, however, so pets have to be stabilized using drugs to treat the thyroid gland several weeks prior to the procedure. Any other underlying or secondary disease is also treated.
