Hyperthyroidism is a common hormonal disorder in older cats, typically those between 12 and 13 years old, though cats of any breed and both sexes can be affected. It is characterized by the excessive production of thyroid hormones by the thyroid glands, located in the neck. These hormones regulate various bodily functions, including metabolic rate. When the thyroid gland produces too much hormone, it leads to a rapid acceleration of metabolism, causing the cat to burn energy too quickly. This results in weight loss, despite an increased appetite.
Understanding Feline Hyperthyroidism
Located in the neck, the thyroid glands produce a range of hormones that balance numerous body processes and control a cat's metabolic rate. If the thyroid gland releases an excessive amount of these hormones, the cat will begin to experience symptoms of hyperthyroidism. Hyperthyroidism will cause rapid acceleration in your cat's metabolism. This means your cat will burn energy too rapidly, leading to weight loss, even if you notice your feline friend has been consuming considerably more food than usual.
Recognizing the Symptoms
Symptoms of hyperthyroidism often develop gradually but grow progressively worse over time. Other underlying health issues can complicate or mask these symptoms. Therefore, it is critical to consult your veterinarian as soon as possible if your cat displays any of the following symptoms, which point to an excess production of thyroid hormones:
- Irritability
- Increasing thirst
- Restlessness
- Mild vomiting or diarrhea
- Increased heart rate
- Low heat tolerance
- Poor grooming habits
- Hearty or increased appetite
In advanced stages, some cats may pant when stressed, which is unusual. While most cats with hyperthyroidism have an exceptional appetite and are restless, others may experience a lack of appetite or feel lethargic or weak.
Causes and Complications
Hyperthyroidism is typically caused by a non-cancerous tumor on the thyroid gland, although in rare cases, the tumor can become cancerous. Left untreated, hyperthyroidism can impact the function of your cat's heart and potentially lead to heart failure. Less frequently, the condition can lead to high blood pressure, which is associated with other severe health issues, including damage to the brain, heart, eyes, and kidneys. Hyperthyroidism and kidney disease often coexist in older cats. When this occurs, each condition will need to be closely monitored and managed, as the management of hyperthyroidism can sometimes negatively affect kidney function.
Read also: Kidney-Friendly Cat Food Explained
Diagnosis
Diagnosing hyperthyroidism in older cats can be challenging. Your vet can conduct a physical examination and examine your cat's neck area to detect signs of an enlarged thyroid gland. Your primary vet may refer you to Veterinary Referral Associates for diagnostic testing and advanced treatment. Several conditions share clinical symptoms of hyperthyroidism, which may mean various diagnostic tests will be needed to diagnose the disease. These tests may include a straightforward blood test that reveals elevated T4 levels in the bloodstream. Your vet may order a complete blood count (CBC), chemistry panel, and urinalysis to eliminate other potential causes such as diabetes and kidney failure. The vet may also assess your cat's blood pressure or order an electrocardiogram, ultrasound, or chest X-ray.
Dietary Management of Hyperthyroidism
Hyperthyroidism in cats can often be managed with a therapeutic diet prescribed by a veterinarian. Cats with hyperthyroidism, especially older felines whose bodies may find it challenging to absorb essential nutrients, can lose a significant amount of weight. Generally, cats with overactive thyroid glans require a high-calorie diet with enough fat, and plenty of high-quality, animal-based protein.
Iodine-Restricted Diets
This iodine-restricted diet aims to decrease the production of thyroid hormones in your cat's body since thyroid hormones require iodine for their production. Strict adherence to the low-iodine diet is crucial to ensure the effectiveness of this treatment. This can be challenging for some pet parents and their cats. In addition to feeding your cat the prescription food, you must closely monitor your cat's treats and prevent them from hunting for mice or birds outdoors. Your cat may not enjoy their low-iodine diet, and the uncomfortable symptoms of hyperthyroidism will probably continue if you try to mix a low-iodine food plan with your cat's regular food. However, it's important to stick to the diet plan prescribed by your vet. To help lower the amount of iodine your cat consumes, your vet may recommend avoiding products such as supplements, human food, and some flavored medications. Studies indicate that following a prescription hyperthyroidism diet for three weeks can lead to a decrease in thyroid hormone levels. Within a few months, these levels may even return to normal. This diet may be used in conjunction with other treatment options such as radioactive iodine (I-131) therapy, antithyroid medication, or surgery to remove the thyroid.
A hyperthyroidism diet for cats should focus on iodine levels limited to 0.32 parts per million or less. Your vet may prescribe high-quality canned or dry cat food specially made for cats with hyperthyroidism. Strict adherence to the low-iodine diet is necessary for this treatment to be effective, which can prove challenging for some pet parents and their cats. Along with feeding your cat prescription food, you will need to avoid giving your cat treats and people food and prevent your cat from hunting for their own meal while outside. If your cat eats any food other than your prescribed diet, this could sabotage the careful balance of iodine necessary to improve hormone levels.
Additional Dietary Considerations
If a diet plan is one component of your cat's treatment, he or she may benefit from eating grain-free food high in energy and protein, which can help your cat regain weight, and muscle mass lost due to their overactive thyroid. Your vet may prescribe specific brands of food depending on your cat's needs. Conversely, if your cat's kidney function has been compromised, more moderate protein levels may be required. For cats with kidney disease, eating too much protein can worsen their symptoms. The high water content in canned food makes it an ideal choice, as this can counterbalance your cat's tendency to produce too much urine due to high thyroid hormone levels. It's also important that your cat has free access to clean water at all times.
Read also: Guide to Raw Feeding for Cats
Some studies show that after three weeks of following a prescription hyperthyroidism diet, levels of T4 thyroid hormones begin to decrease. Within a few months, they may even return to normal levels. Once your cat's thyroid levels have been normalized with methimazole, thyroidectomy, or radioactive iodine therapy, and the cat has regained a healthy amount of weight, their diet plan can be adjusted to meet their needs.
Tips for Choosing the Right Cat Food
When it comes to a hyperthyroid diet for cats, there are a few tips to help keep your furry friend on the mend, including:
- Do feed your cat:
- Canned or raw diets that contain little to no fruits, vegetables, or grains.
- Any canned cat food is better than any dry, which contains too much carbohydrate and plant-based protein.
- Meat by-products are fine for carnivores: they’re simply protein sources such as organ meats and entrails that people don’t find appetizing.
- Pate-style foods. Gravy-based foods tend to be high in carbs.
- It may be best to avoid:
- Soy-containing foods.
- BPA (Bisphenol A) in canned food linings.
- Fish and fish by-products.
- Plastic food and water bowls (use glass, ceramic, or metal instead).
- Storing food in plastic containers.
- Ultra-high or ultra-low iodine diets.
Important: If your cat is being fed a prescription iodine-restricted diet specifically for hyperthyroidism, they cannot be fed any other foods. This includes all types of treats, snacks, and human foods.
Other Treatment Options
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
Prognosis
If the condition is diagnosed and treated early, the prognosis for cats suffering from hyperthyroidism is generally good. In some cases where the condition has become more advanced, complications with other organs can worsen the prognosis.
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The Importance of Veterinary Consultation
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.
What Happens When Hyperthyroidism Goes Untreated?
As with most conditions, leaving hyperthyroidism untreated can lead to serious complications. Your cat will become more ill over time. You may notice symptoms such as blood in their stool, and they may not eat very much, which can lead to other issues. Many cats that are suffering from untreated hyperthyroidism experience potentially fatal heart issues due to their heart working extra hard to keep your cat's body running.
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