Today, our Elk Grove vets talk about hyperthyroidism in cats, including the causes and symptoms of this disease, and the treatment options available.
Cats & Hyperthyroidism
Hyperthyroidism develops when a cat’s thyroid glands become overactive. It’s a very common disorder caused by an increase in the production of thyroid hormones by the thyroid glands, that are located in the neck.
Thyroid hormones are used to regulate many processes in the body and control metabolic rate. When too much of the hormone is produced, clinical symptoms can be quite dramatic and make cats severely sick.
Cats suffering from hyperthyroidism tend to burn energy too quickly, which makes them lose weight, despite their increased appetite.
Symptoms & Signs of Hyperthyroidism In Cats
This condition is most often seen in cats that are middle-aged and older. Most kitties are between 12 and 13 years of age when the disease becomes a problem. Both males and females are equally likely to become impacted.
The most common signs of hyperthyroidism in cats include:
- Typically a healthy or increased appetite
- Increase in thirst
- Poor grooming habits
- Increased irritability or restlessness
- Elevated heart rate
Some cats will also develop mild to moderate diarrhea and/or vomiting, while others will have a low tolerance to heat and search for cooler places to lounge.
In advanced cases, some cats pant when they become stressed (an unusual behavior for kitties). Also, while most cats will have a good appetite and be restless, some may feel weaker, lethargic, or have a lack of appetite. The key is to monitor for significant changes in your cat and have them addressed as early as possible.
These symptoms are usually subtle at the beginning and gradually become more severe as the disease gets worse. Other diseases can also complicate and mask these symptoms, so it’s imperative to see your vet early.
The Causes of Cat Hyperthyroidism
For most cats, benign (non-cancerous) changes in their bodies can trigger the condition. In most cases, both thyroid glands are involved and become enlarged (the clinical change is nodular hyperplasia, and it resembles a benign tumor).
While we don't know what causes the change, it is fairly similar to hyperthyroidism in humans (clinically named toxic nodular goiter). Rarely, a cancerous (malignant) tumor called thyroid adenocarcinoma is the underlying cause of this disease.
Long-term Complications of Hyperthyroidism In Cats
If it goes untreated, hyperthyroidism can impact the function of your cat's heart, changing the organ’s muscular wall and increasing heart rate. It can eventually result in heart failure.
Another potential complication is high blood pressure (hypertension). While this is seen less often, it can cause damage to several organs including the brain, kidneys, heart, and even the eyes. If your vet diagnoses your cat with hypertension in addition to hyperthyroidism, medication will be needed to control blood pressure.
Hyperthyroidism and kidney disease often occur at the same time, as they are both commonly seen in older cats. When both of these conditions are present, they need to be closely monitored and managed as managing hyperthyroidism may sometimes adversely affect kidney function.
Diagnosing Hyperthyroidism in Cats
It can be tricky to diagnose hyperthyroidism in senior cats. Your vet will conduct a physical examination and palpate your cat’s neck area to look for an enlarged thyroid gland. At Bruceville Pet Hospital, our Elk Grove vets are trained in internal medicine and have access to a variety of diagnostic tools and treatment methods.
A range of tests will probably be needed to diagnose your cat's hyperthyroidism, 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 showing elevated T4 levels in the bloodstream might be enough for a definitive diagnosis, however, this isn't true for all cats. Concurrent illnesses or mild cases of hyperthyroidism, can cause fluctuating levels of T4 or show 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.
Treating Cats With Hyperthyroidism
Your vet might use one of several treatment options for your cat’s hyperthyroidism, depending on your pet’s specific circumstances and the advantages and disadvantages of each option. Your kitty's treatment may include:
- Antithyroid medication, administered orally, to control the disease for either the short-term or long-term
- Dietary therapy
- Radioactive iodine therapy (likely the safest and most effective treatment option)
- Surgery to remove the thyroid gland
The Prognosis For Cats That Have Hyperthyroidism
The prognosis for cats that have hyperthyroidism is generally good if they are provided with the appropriate therapy early. Sometimes, complications with other organs can make the prognosis worse.
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.