Middle-aged and senior cats sometimes develop hyperthyroidism. Our Gaithersburg vets discuss symptoms, diagnosis, and treatment options for this disease.
What is hyperthyroidism in cats?
A cat's thyroid glands are located in its neck. Sometimes, these glands can become overactive and cause hyperthyroidism, a widespread disorder in felines.
Thyroid hormones regulate many processes throughout the body. They also control the metabolic rate. When too many of these hormones are produced, it accelerates a cat's metabolism, which can negatively impact nearly every organ in the cat's body (including the heart and kidneys), lead to dramatic clinical symptoms, and trigger severe illness in cats.
Kitties suffering from hyperthyroidism tend to burn energy too quickly, which leads to weight loss even though your cat will often have a more robust appetite and be eating more food.
Our vets in Gaithersburg often prescribe iodine treatment (I-131 therapy) is for cats with hyperthyroidism.
We'll list more symptoms of the disorder and discuss treatment in detail in this post.
What are the symptoms of hyperthyroidism in cats?
Cats that are diagnosed with. hyperthyroidism are typically middle-aged (8 or older). Most are older than 10 - between 12 and 13 - when the disorder becomes an issue. The condition impacts male and female cats in equal numbers.
Common symptoms of hyperthyroidism in cats include:
- Poor grooming habits
- Typically a healthy or increased appetite
- Increased restlessness or irritability
- Rapid or irregular heartbeat
- Increase in thirst
Some cats may also suffer from vomiting and/or mild to moderate diarrhea, while others will have a low tolerance to heat and seek cooler places to lounge (such as your bathroom floor or bathtub).
Your cat may also pant when stressed if the disease has advanced (an unusual behavior for our feline friends). While most cats will have a healthy appetite and remain active, some may appear to be weak, lethargic, or lack appetite. The key is to notice any significant changes in your cat and make an appointment with your vet so they can be addressed as soon as possible.
These symptoms usually appear subtle in the first stages of the disorder and gradually grow more severe as the underlying disease gets worse. These symptoms can also be complicated and masked by other diseases, so it's important to see your vet early.
What causes hyperthyroidism?
For most kitties with this disorder, this condition is triggered by benign (non-cancerous) changes in the body. Both thyroid glands are usually involved and become enlarged (clinically referred to as nodular hyperplasia, which resembles a benign tumor).
While we aren't sure what causes these changes, it is similar to hyperthyroidism in humans (clinically called toxic nodular goiter). The disorder is occasionally caused by a malignant (cancerous) tumor called thyroid adenocarcinoma.
What are the long-term complications of hyperthyroidism?
Untreated hyperthyroidism can affect how the heart functions, changing the organ's muscular wall and increasing the heart rate. It can eventually lead to heart failure.
High blood pressure (hypertension) is another potential complication. While we see this less often, it can cause damage to several organs, including the heart, brain, kidneys, and even the eyes. If your vet diagnoses your cat with hypertension due to hyperthyroidism, medication will be needed to control blood pressure.
While hyperthyroidism and kidney disease often occur at the same time, they are both commonly diagnosed in older cats. When both of these conditions are present, your vet will need to monitor them closely, as managing hyperthyroidism can sometimes adversely affect kidney function.
How is hyperthyroidism in cats diagnosed?
If you suspect your cat may have hyperthyroidism, contact your veterinarian right away to book an exam.
During your cat's physical exam, the vet will feel your cat's neck for an enlarged thyroid gland and check for clinical signs of the condition. Your kitty's medical history will also be taken into consideration.
A battery of tests will likely be needed to diagnose hyperthyroidism in your cat, as many other common diseases experienced by senior cats (intestinal cancer, chronic kidney failure, diabetes, inflammatory bowel disease, and more) share clinical symptoms with hyperthyroidism.
A complete blood count (CBC) urinalysis and chemistry panel can help rule out kidney failure and diabetes.
A simple blood test demonstrating elevated T4 levels in the bloodstream may be sufficient for a definitive diagnosis, though this is not true for 100% of cats due to concurrent illnesses or mild cases of hyperthyroidism, which can result in fluctuating T4 levels or showing elevated T4 levels if another illness is influencing the result.
If possible, your vet may also check your cat’s blood pressure and perform an electrocardiogram, chest x-ray, or ultrasound.
What are treatment options for hyperthyroidism in cats?
Based on your pet's unique circumstances and the advantages and disadvantages of each option, your vet may recommend one of several treatment options for your feline friend's hyperthyroidism.
Our veterinarians offer radioactive iodine treatment (also referred to as I-131 therapy and radio-iodine treatment) for cats with hyperthyroidism at our animal hospital in Gaithersburg. This is often the safest and most effective treatment option for this disease.
Other treatment options may include:
- Antithyroid medication, administered orally, to control the disease for either the short-term or long-term
- Surgery to remove the thyroid gland
- Dietary therapy
How long do cats with hyperthyroidism live?
Most cats that are diagnosed with hyperthyroidism and have this disorder treated with effective medical management will live an average of three to five years before dying of either heart failure or kidney failure. However, those three to five years can still provide lots of good, quality time with their owners.
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.