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Cats give us endless love and companionship, enriching our lives in countless ways and ensuring their health and well-being is a crucial part of our responsibility.
As they age, various conditions can emerge that may affect their quality of life. One such condition is hyperthyroidism, a prevalent issue among middle-aged and elderly cats. It's a topic every cat owner should be well-informed about but the real challenge lies in identifying its subtle symptoms early on and understanding the best course of action for treatment.
In this episode of the Call the Vet podcast, Dr. Alex Avery dives deep into everything you need to know about hyperthyroidism—from recognizing key signs and symptoms to exploring various treatment options, so you can ensure a healthy, happy life for your feline friend.
“The reality is that if it’s successfully treated, if it’s picked up soon enough, it’s if it’s treated successfully, then hypothyroidism need have no impact to your cat’s life.”
As a veterinarian, I've seen countless cases of hyperthyroidism in middle-aged and elderly cats, and the importance of recognizing this condition early cannot be overstated.
What is Hyperthyroidism?
Hyperthyroidism is essentially an overproduction of thyroid hormone in cats.
The thyroid glands, located on either side of the neck, produce hormones that regulate the body's metabolic rate, which directly impacts how cells function. When these glands produce excess thyroid hormone, it causes the body to work overtime.
This overactivity depletes the body's energy reserves and affects multiple organ systems.
A benign growth of the thyroid tissue causes the vast majority of cases of hyperthyroidism. While less common, there are instances of malignant thyroid tumors which can be significantly more challenging to treat.
Recognizing the Symptoms of Hyperthyroidism in Cats
One of the most prominent and telling signs of hyperthyroidism in cats is weight loss despite an increased appetite.
Your cat may seem ravenous, yet they continue to lose weight. This happens because their body is working so hard that it burns through calories at an accelerated rate, leaving them constantly hungry.
Other symptoms to watch for include anxiety, changes in personality, and a deteriorating coat condition. The cat’s fur may become dry, matted, and unkempt.
Additionally, you might notice vomiting, diarrhea, increased thirst, and more frequent urination.
In severe cases, increased blood pressure can lead to sudden blindness due to retinal detachment.
This is the most common picture, but a small subset of cats show atypical signs of reduced appetite and lethargy.
Diagnosing Hyperthyroidism in Cats
Diagnosing hyperthyroidism typically involves a physical examination and blood tests.
If I suspect a cat has hyperthyroidism because of history and body condition loss, I start by feeling their neck to check for enlarged thyroid glands. Although thyroid enlargement isn't always detectable, finding it increases the likelihood of a hyperthyroidism diagnosis.
During the physical exam, I also listen to the cat's heart.
Abnormal heart rhythms (most commonly a gallop rhythm) or murmurs may further indicate hyperthyroidism.
The definitive diagnosis, however, comes from a blood test measuring the levels of thyroid hormone (T4).
Elevated levels of T4 confirm hyperthyroidism. In some instances, where T4 levels fall in a gray area, retesting or additional tests such as a free T4 test may be necessary for a conclusive diagnosis.
Treatment Options for Hyperthyroidism
Once your cat is diagnosed with hyperthyroidism, the next step is choosing an appropriate treatment. Fortunately, there are several effective treatment options available.
Oral Medication
Traditionally, hyperthyroidism was managed with twice-daily tablets.
However, more recently, once-daily medication has become available, making it easier for pet owners to manage.
For cats that are difficult to medicate, transdermal gels can be applied to the inside of their ears, providing an effective alternative. It's important to wear gloves while applying the gel to prevent absorption into your own skin.
If the medication (or diet) is stopped hyperthyroidism will recur, making this a lifelong treatment rather than cure.
Special Diet
An iodine-restricted diet, specifically Hill’s Y/D, can also effectively control hyperthyroidism in cats.
Iodine is essential for thyroid hormone production, and restricting iodine intake can help balance thyroid hormone levels.
It's crucial that cats on this diet consume only the prescribed food, as even small amounts of other food has the potential to compromise the diet’s effectiveness.
This option is best suited for single-cat households where controlling food intake is feasible.
Long-Term and Curative Treatments
Surgical Removal
Surgical removal of the thyroid glands is another treatment option, though it's less commonly performed today.
This procedure involves removing one or both of the thyroid glands.
However, if both glands are removed, there is a risk of hypothyroidism or accidental removal of the parathyroid glands, which can cause additional complications.
Radioactive Iodine Treatment
Radioactive iodine treatment (I-131) is considered a potentially curative option.
This treatment involves injecting radioactive iodine, which is absorbed by the thyroid gland and destroys the overactive thyroid tissue.
While it requires a hospital stay of one to two weeks, it effectively cures most cats of hyperthyroidism.
However, availability may vary depending on your location, and the treatment may be expensive initially. In the long run, it could save costs associated with ongoing medication and monitoring.
If I ever have a hyperthyroid cat then this is the option I will be opting for!
Post-Treatment Monitoring and Additional Conditions
Regardless of the chosen treatment method, regular monitoring is essential to ensure the treatment’s effectiveness and to check for other health conditions.
After starting treatment, it’s crucial to monitor your cat’s thyroid hormone levels and kidney function. Sometimes, pre-existing kidney conditions can become apparent only after treating hyperthyroidism.
Additionally, arthritis, a common condition in older cats, may become noticeable once hyperthyroidism is under control.
Final Thoughts
Hyperthyroidism is a manageable condition with several viable treatment options.
Early diagnosis and consistent treatment can ensure that your cat lives a healthy and happy life. By being aware of the symptoms and understanding the treatment choices, you can make informed decisions that are in the best interest of your furry family member.
If you found this information helpful, please share it with other cat owners and subscribe to our podcast for more insights on pet health. Your cat deserves the best care, and staying informed is the first step in providing it.
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