Top 10 Signs Of Hyperthyroidism In Cats

As we are familiar with, hyperthyroidism, in the case of humans, is nothing different in animals, specifically in catså. The enlarged thyroid glands produce the excessive growth of thyroid hormone. It also affects the metabolic rate in cats.

Cats have two thyroid glands on either side of the neck. The general appearance of this disorder is seen in the age category of older cats. In several cases, the cause of this disorder is a non-cancerous tumor referred to as adenoma.

In more minor possible cases, the thyroid is due to a malignant tumor termed adenocarcinomas. Hyperthyroidism has always turned out to be a must-have to deal with disorder, for it affects almost all other body parts resulting in secondary symptoms. Therefore, this unwanted growth of the thyroid gland demands immediate treatment.

Signs Of Hyperthyroidism

The observatory signs of hyperthyroidism in cats are easily noticeable for any cautious owner. The characters might be mild in the initial stages. However, with time, the depth of these symptoms would increase.


The most common mistake of the owners is being ignorant of these behavioral changes and merging them with aging. But any owner who is a bit careful enough would end up playing with a healed and healthy cat. To understand further, let’s get down to the list of symptoms.


  • Weight Loss

The first and easily noticeable symptom is the one with the weight. It is subtle and standard for any disorder to result in weight loss. It happens due to an unwanted increase in the metabolic rate. The cats, due to their discomfort, may act aggressive or restless. Growling, scratching, and unpredictable actions may also be witnessed. It results in metabolic abnormalities.


  • Increased Appetite

It is an automatic response to higher metabolic rates. Because of the expenditure of all the stored energy, the cat’s body demands more yield of energy. Thus, comes the appetite. The fulfillment of the greater appetite also doesn’t last long due to metabolism, and this loop goes on.


  • Vomiting

Due to excessive intake of food in less time, gastrointestinal malfunctioning such as vomiting takes place. The action of hormones of the thyroid gland or the chemoreceptor trigger area of the brain may also be the reason behind vomiting.


Sometimes, the emptying of feces in delayed time, also known as gastric stasis, leads to vomiting and regurgitation. Hyperthyroid cats generally vomit after taking food.


Cats living in multi-cat households are at higher risk of showing these signs. The solution to such vomiting symptoms lies in feeding your animal more frequently and moderating the amount of food each time.

  • Increase In Thirst & Urination

This symptom is also known as PU/PD by veterinarians. PU refers to the condition of increased thirst. PD refers to the state of increased urination.


Most cats above 12 years, about one-third of them, develop mild kidney disease. It is the reason behind why about one-half of hyperthyroid cats also suffer from kidney disease. The main reasons behind these symptoms of kidney disease are:


● The cat’s kidney cannot concentrate the urine due to the increase in blood flow to the kidney. This condition may also be termed as renal medullary washout, where the cat’s kidneys cannot function properly.

● An increase in water consumption is also noticed as a response to hyperthyroidism. Thus, these behavioral symptoms also lead to PU/PD.


However, these symptoms gradually disappear after the cat starts recovering from hyperthyroidism.

  • Anxiety

In hyperthyroidism, the cats undergo increased central nervous system stimulation, which leads to feelings of confusion, restlessness, and anxiety. It may further result in sleep patterns with constant interruption.

As a response to all these neurological symptoms, the hyperthyroidism cat may wake up at night and start yowling without any reason. However, these symptoms of anxiety fade away during treatment.


  • Nervous Behaviour

The sedentary behavior of cats as their age progresses is normal. However, hypes in regular activity leading to hyperactivity indicate an underlying health condition, especially hyperthyroidism.


Hyperthyroid cats also show symptoms of a panic attack, aggression, intolerance to stress, and restlessness. As a result of these behavioral symptoms, the cat may further start panting and develop signs of weakness and respiratory distress.


In extreme cases of such nervous behavior and hyperactivity, the cat may also collapse. The expression of hyperactivity and nervousness through tremors and twitching of muscles in hyperthyroid cats is also noticed.

  • Diarrhea

Due to gastrointestinal malfunctioning, the cat’s intestines are unable to absorb the food properly. In addition to this, overeating also turns out to be problematic. Thus, symptoms of diarrhea, frequent defecation and an increase in the numbering of feces are also the signs of hyperthyroid cats.

  • Breathing Problems

Stress is common in hyperthyroid cats. As a result, abnormalities in respiration and breathing rate, panting are the common symptoms in such cats. These symptoms may also affect the central nervous system of the body.


When left untreated, these symptoms become severe every passing day. As a result, the cat collapses either due to shortness of breath or heart failure.

  • Changes In Skin, Hair, And Nail 

In hyperthyroidism, cats generally develop dull, unkempt, and matted hair. An increase in grooming and licking activities are also observed, which leads to conditions of miliary dermatitis and alopecia.


Alopecia refers to baldness in cats. On the other hand, military dermatitis refers to crusty rashes on the skin accompanied by excessive itching. Moreover, thickened and lengthened nails with excess fragility are also the symptoms of hyperthyroidism.

  • Apathetic Hyperthyroidism

Hyperthyroid cats generally exhibit signs such as hyperactivity, nervousness, and respiratory distress. However, about 5% of hyperthyroid cats may contradict these symptoms. They show symptoms of poor appetite, depression, and weakness. This condition is termed apathetic hyperthyroidism.


Apathetic hyperthyroidism indicates the presence of some significant secondary disease in the cats. These underlying symptoms include heart disease, renal failure, or cancer. Hence, the vet needs to be very careful while identifying and treating a cat with apathetic hyperthyroidism.


What Breed Of Cat Is Likely To Get Affected By Hyperthyroidism?

Cats with a higher age count are more vulnerable to hyperthyroidism. Besides that, the possibility of suffering from hyperthyroidism can also derive influence by environmental components.


More than needed amount of iodine also fuels the risk of hyperthyroidism. However, the answer to the above question has not to be confined to any responses yet. The factors which lead towards hyperthyroidism are flexible with all types of cat species.


But, some exceptional breeds have a lesser risk of being prey to hyperthyroidism. The list of such species includes Persian, Burmese, Himalayan, Abyssinian, which have a diminished chance of getting into hyperthyroidism.

What Causes Hyperthyroidism?

In the medical world, there is still some illness that has no specific reason. The closest to coming up with a root cause is a prediction of a handful of factors that might have influenced illness.


Hyperthyroidism in cats is among such unsolved illnesses. To date, a specific root cause hasn’t been provided when it comes to hyperthyroidism in cats. However, as discussed before this, there could be few elements from the surrounding environment which encourage hyperthyroidism.


On top of it, we very well know the outcome of more than needed iodine. Thus, here is one of the most suspected and nearly confirmed reasons behind hyperthyroidism, not the only one, though.

Diagnosis Of Hyperthyroidism

For any out-of-order alignment in a body, be it a human or animal, the first approach ought to be the physical diagnosis. A veterinarian will firstly go for verification of an enlarged thyroid gland in the cat’s throat.


The vet relies on his sense of touch to determine whether the cat is suffering from hyperthyroidism. The following step involves a check on blood pressure and heart rate. In addition to that, a blood test for the level of thyroid hormone is essential.


The foremost thing to notice when the reports of blood tests are handed is the thyroid hormone, i.e., T4. The expected results include a higher level of T4 among the cats which have hyperthyroidism.


On the other hand, some cats have a surprisingly average level of T4 even when the doctor suspects hyperthyroidism. It would require extra tests to be run, which include a T4 free test. Also, if not satisfied, a thyroid scan can provide us with the internal condition of the cat.


As hyperthyroidism influences the malfunctioning of other body parts, a secondary check-up is also a vital part of the diagnosis. The kidney and heart are the most vulnerable ought to be paid emphasis on. Even though all this hasn’t met your satisfaction yet, an urine analysis might do the job.

Treatment of Hyperthyroidism

Based on the symptoms your cat exhibits, the vet would analyze the severity of the cat’s condition. After this, the vet would plan the treatment measures and procedures for your cat. However, the primary treatment options available are:


Anti-thyroid drugs can reduce the secretin from thyroid glands in cats. However, these medications are meant explicitly for short-term treatment.


If you wish for a long-term cat, you can administer the medications twice a day. Although these medications are readily available at affordable prices, they may lead to allergic reactions in cats.


Regular checkups and blood tests are essential to check the recovery rate and detect possible side effects.

Radioactive Iodine Therapy

Radioactive iodine, I-131, is one of the best ways to destroy the abnormal and malfunctioning thyroid tissues without any threat to other organs. Within 1-2 weeks of therapy, the cat gets fully treated for hyperthyroidism. The need for daily medication is also eliminated.


Cats with hyperthyroidism are generally above eight years. In case the cat doesn’t have any other secondary health problem, the risks involved in the surgical method of treatment are minimal.


Also, the cat should not have hyperthyroid ectopic tissues starting from the tongue to the heart. Thus, proper nuclear and diagnostic tests are necessary before the surgery. These tests determine the particularly affected thyroid lobe.


Antithyroid medications before the surgery are also essential for the cat. After the surgery, regular checkups for measuring thyroid levels are mandatory.


Some owners may not desire to make their cat undergo radiation therapy due to the advancing old age of their animal. However, the treatments are to decrease the thyroid levels in the blood. However, the excessive decrease is also not a good sign.


Hence, talk to your vet for a personalized treatment plan. Irrespective of what the treatment is, the results of these treatments may make the animal return to its normal lifestyle.


Proper diet and medication during the treatment are essential. Nevertheless, timely checkups, blood tests, and diagnostic tests are mandatory to track the cat’s response to the ongoing treatment.


How Long Can A Cat Live With Untreated Hyperthyroidism?

The physical drift in a cat suffering from hyperthyroidism leads to misconceptions of the cat’s aging. This misconception tends their owners to ignore this condition, resulting in leaving the actual cause untreated.


The cat cannot speak up to its owner but suffers within, fatal and devastating. Thus, a responsible owner can cut off all this chaos. The general behavior of cats with prolonged hyperthyroidism should be different compared to the rest of the normal ones. 


An untreated cat with hyperthyroidism shows an unwillingness to feed, an excessive hair loss from the body, has worn a sick appearance over time, also seems to have a sluggish inactive attitude. These are some factors to keep an eye on. Thus an immediate treatment is necessary, or else the duration for your cat to breathe would diminish at a constant pace.

How To Prevent Hyperthyroidism In Your Cat?

To date, there is no preventive measure that you can follow to save your cat from getting affected with hyperthyroidism. The only step you can take is to cure it at its earliest stages. Cure at the earliest stages protects your cat from other secondary diseases which are deadly.


All cats above six years of age should undergo blood and urine tests annually. In the case of senior cats, a complete physical examination every six months is mandatory. Moreover, the owner should also keep noticing the glands of the cat. Any changes, minor or significant, should be reported to the vet at the earliest.

Final Takeaway

Detection of the disease at the earliest stages solves almost half of the issues. Moreover, with proper diet and nutrition, the cat can quickly recover from hyperthyroidism.


However, even after total recovery, the owner should carry on with the diet and nutrition. That’s because the symptoms may start reappearing with hormonal imbalances.

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