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Diet For Cats With Hyperthyroidism

Your cat's thyroid gland releases hormones that regulate numerous body processes. Your cat risks developing serious health issues when thyroid hormone levels become excessive (hyperthyroidism). In this article, our vets in Houston County explain how cat hyperthyroidism can be managed through dietary changes. 

What is hyperthyroidism in cats?

The thyroid glands are located in your cat's neck. These glands produce hormones that regulate various body processes and control metabolic rates. If your cat's thyroid produces too many or too few hormones, it may experience hyperthyroidism or hypothyroidism symptoms.

The difference between the two is that one produces an excessive amount of hormones, which results in hyperthyroidism, and the other produces insufficient hormones, which results in hypothyroidism.

What causes hyperthyroidism?

Hyperthyroidism in cats is primarily caused by an overproduction of thyroid hormones, specifically thyroxine (T4), by the thyroid glands. This condition most commonly occurs due to a benign tumor called a thyroid adenoma, which develops within one or both of the thyroid glands located in the neck.

Thyroid adenomas are typically functional tumors, meaning they actively produce excessive amounts of thyroid hormones regardless of the body's needs. As a result, the cat's metabolism is significantly elevated, leading to a wide range of symptoms such as weight loss despite increased appetite, excessive thirst and urination, hyperactivity, restlessness, vomiting, diarrhea, unkempt appearance, and sometimes cardiac issues like rapid heart rate or heart murmurs.

Although less common, hyperthyroidism can also result from thyroid carcinoma, a malignant tumor of the thyroid gland. In such cases, treatment may differ due to the aggressive nature of the cancer.

Several factors may contribute to the development of hyperthyroidism in cats, including genetic predisposition, environmental factors, and dietary influences. However, the exact cause of thyroid adenomas remains unclear, and further research is ongoing to better understand the underlying mechanisms of this condition.

What are the symptoms of hyperthyroidism in cats?

While any breed of cat can suffer from hyperthyroidism, most cats diagnosed with this condition are older. Typically between 12 and 13 years old. Female and male cats are equally impacted.

The symptoms of hyperthyroidism in cats can be difficult to detect in the initial stages but can worsen gradually over time. Additionally, other underlying health problems can complicate or conceal the symptoms of hyperthyroidism. Therefore, if your cat displays any of the symptoms mentioned below, you should visit a veterinarian immediately.

Cats that produce excessive thyroid hormone may display one or more of the following symptoms:

  • Increase in thirst
  • Irritability
  • Restlessness
  • Mild diarrhea and vomiting
  • Increase in heart rate
  • Poor grooming habits
  • Hearty or increased appetite
  • Low heat tolerance 

As hyperthyroidism progresses in cats, some may begin panting when stressed, which is not common for felines. While most hyperthyroid cats tend to have an increased appetite and become more active, others may display signs of weakness, lethargy, or loss of appetite.

What are the long-term complications of hyperthyroidism?

If left untreated, hyperthyroidism can have a long-term impact on your cat's health, leading to various complications, including:

  • Heart Issues: Left untreated, hyperthyroidism can lead to heart problems such as heart failure. The increased metabolic rate associated with hyperthyroidism puts additional strain on the heart, leading to potential complications.
  • High Blood Pressure (Hypertension): Hyperthyroidism can also cause high blood pressure in cats. Persistent hypertension can damage various organs, including the brain, kidneys, heart, and eyes. Managing blood pressure is crucial to prevent these complications.
  • Kidney Disease: Hyperthyroidism and kidney disease often occur simultaneously in older cats. The presence of both conditions requires careful monitoring and management, as treating hyperthyroidism can sometimes affect kidney function adversely.
  • Other Organ Damage: Prolonged hyperthyroidism may lead to damage in other organs due to the increased metabolic activity and potential complications such as hypertension. These organs include the brain, kidneys, heart, and eyes.
Cat owners must know these long-term complications and seek prompt veterinary care for their feline companions if hyperthyroidism is suspected. Early diagnosis and treatment can help mitigate these risks and improve the long-term prognosis for affected cats.

How is hyperthyroidism diagnosed?

Veterinarians typically begin with a physical examination, palpating the thyroid gland in the neck to check for enlargement or irregularities.

Various diagnostic tests are then used to confirm the diagnosis. These tests may include blood tests to measure thyroid hormone levels, such as a complete blood count (CBC) and a chemistry panel, which can help rule out other conditions like kidney failure or diabetes.

A urinalysis may also be conducted to assess kidney function and check for abnormalities. Imaging studies such as X-rays, ultrasound, or even an electrocardiogram may also be performed to evaluate the thyroid gland and assess for any complications or related conditions.

Combining these diagnostic tests helps veterinarians accurately diagnose hyperthyroidism in cats and determine the most appropriate treatment plan.

How will my vet treat my cat’s hyperthyroidism?

Depending on the results of your cat's tests, your vet may choose one of several treatment options for your cat’s hyperthyroidism.  They may include:

  • Radioactive iodine therapy (likely the safest and most effective treatment option)
  • Antithyroid medication
  • Surgery to remove the thyroid
  • Modified diet

How can hyperthyroidism in cats be treated with a modified diet?

Hyperthyroidism in cats can be treated with a modified diet that aims to restrict iodine intake. Iodine is essential for the production of thyroid hormones, so reducing its levels in the diet can help decrease the production of these hormones by the thyroid gland.

Cat owners can effectively manage their cat's hyperthyroidism by strictly adhering to an iodine-restricted prescription diet prescribed by a veterinarian. This approach typically involves feeding the cat specialized prescription food and closely monitoring its treats to ensure it does not consume additional iodine.

Studies suggest that after a few weeks of following this diet, thyroid hormone levels may begin to decrease, and within a few months, they may even return to normal levels. It's essential for cat owners to work closely with their veterinarians to ensure the proper implementation and monitoring of the modified diet for the effective treatment of hyperthyroidism in cats.

What is the prognosis for cats with hyperthyroidism?

The prognosis for cats with hyperthyroidism can vary depending on several factors, including the cat's age, overall health, the severity of the condition, and the chosen treatment approach. However, with appropriate management, the prognosis for cats with hyperthyroidism is generally favorable.

Most cats respond well to treatment for hyperthyroidism, which typically involves medication, radioactive iodine therapy, or surgery.

Medication, such as methimazole, is commonly used to control the overproduction of thyroid hormones and can effectively manage the symptoms of hyperthyroidism in many cases. However, long-term medication may require regular monitoring and adjustments to dosage.

Radioactive iodine therapy is another option for curing hyperthyroidism by selectively destroying the abnormal thyroid tissue. This treatment is highly effective and well-tolerated by most cats, but it may require specialized facilities and can be more expensive than medication.

Surgical removal of the thyroid gland (thyroidectomy) is another treatment option, particularly for cats that are not good candidates for medication or radioactive iodine therapy. While surgery can provide a permanent solution to hyperthyroidism, it carries some risks and requires careful post-operative care.

Overall, with appropriate treatment and management, most cats with hyperthyroidism can enjoy a good quality of life and have a favorable long-term prognosis. Regular veterinary check-ups and monitoring are essential to ensure the ongoing health and well-being of cats with this condition.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

If you suspect your cat may be suffering from hyperthyroidism, our vets can help! Contact our Houston County vets today to book an appointment for your feline friend.

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