If hyperthyroidism persists for longer than three to six months after treatment, re-treatment with radio iodine is generally recommended to cure the disorder. Virtually all cats that remain hyperthyroid after the first treatment are cured by the second treatment. Can the hyperthyroidism ever reoccur?
Full Answer
Can a cat with hyperthyroidism have surgery?
Surgical Treatment for Hyperthyroidism in Cats. There are four different ways a cat with hyperthyroidism may be treated: medication, radiation, chemical ablation or surgery. A thyroidectomy, surgical removal of the thyroid, is a popular treatment option for cat owners.
How is radioactive iodine used to treat hyperthyroidism in cats?
Radioactive Iodine Therapy. When available, radioactive iodine therapy is the treatment of choice for cats with hyperthyroidism. During treatment, radioactive iodine is administered as an injection and is quickly absorbed into the bloodstream.
How do you treat hyperthyroidism in dogs?
Treatment options for hyperthyroidism include surgery (if one lobe is involved), diet to reduce iodine exposure (using a prescription diet), medical treatment with methimazole (Tapazole®), or I-131 radioactive therapy. These treatment options have different pros and cons and should be discussed with a veterinarian.
What are the treatments for thyroid problems in cats?
A thyroidectomy, surgical removal of the thyroid, is a popular treatment option for cat owners. The ideal surgical candidate is a cat that deals well with anesthesia, whose thyroid gland is not too large and the thyroid tissue has not migrated to other parts of a cat's body.
When should I recheck my hyperthyroid cat?
Most hyperthyroid cats are euthyroid within 2–3 weeks of commencing treatment with antithyroid drugs,44,65,82,83 and so T4 should be monitored after that time period.
Can cats get hyperthyroidism twice?
Cats that have had surgery may have a recurrence of hyperthyroidism. Blood thyroid hormone levels should be measured once or twice a year. Radioactive iodine is given intravenously and will accumulate in the abnormal thyroid tissue, killing the abnormal thyroid cells but sparing the normal thyroid cells.
How long can a cat live on hyperthyroidism medication?
The median survival times reported are 25 (iodine 131 treatment),1 24 (radioiodine treatment),2 and 48 months (iodine 131 treatment),3 with a more recent paper citing 14 months (carbimazole or methimazole treatment alone or in combination with thyroidectomy).
What are the final stages of hyperthyroidism in cats?
Over time, this progresses to increased blood pressure, severe weight loss, heart disease, blindness, and kidney damage. The slow onset of signs means that cat owners will often miss these changes until the late stages of disease.
How long does it take for thyroid levels to stabilize?
If your healthcare provider treats your condition with antithyroid medications (methimazole or propylthiouracil) your hormone levels should drop to a healthy level in about six to 12 weeks.
Can feline hyperthyroidism return after radioactive iodine?
Most hyperthyroid cats respond fully to a single injection with radio-iodine. Their hyperthyroidism won't come back, and they don't need ongoing medication. Most cats respond to treatment within weeks, although some take up to 6 months to gain the full benefit.
Should I put my cat down with hyperthyroidism?
When to put a cat to sleep with hyperthyroidism is a heartbreaking decision. If your cat is in pain and has lost a lot of weight or declining health, then it may be time to consider euthanasia. If your cat, however, is still relatively healthy and comfortable, then you may want to wait a little longer.
How long can a cat live taking methimazole?
The cost of methimazole and laboratory monitoring easily pay for 131I therapy after the first year, and the tumor continues to grow! The average life expectancy of a methimazole patient is ~3 years.
Do cats ever recover from hyperthyroidism?
Fortunately, the vast majority of cats that develop hyperthyroidism can be treated very successfully and most cats will make a complete recovery.
How do you know when your cat is dying of hyperthyroidism?
Weight loss The weight loss associated is generally progressive and is usually first noticed by the owner as a loss of muscle mass around the cat's back (spine). With time, severe muscle wasting, emaciation, and death from starvation can occur if the cat's hyperthyroidism is left untreated.
Is my cat in pain with hyperthyroidism?
In addition, hyperthyroidism can cause hypertension or high blood pressure, and result in damage to the eyes, kidneys, and brain. Cats with untreated hyperthyroidism can also endure pain and a lower quality of life due to the symptoms of the disease.
How can I fatten up my cat with hyperthyroidism?
Hyperthyroid cats need high calorie and high protein diets to reduce the rate of weight loss and muscle wasting that accompanies the disease. Thyroxine (the major hormone produced by the thyroid gland) is one of numerous counter-regulatory or anti-insulin hormones. As such it's effects are opposite to those of insulin.
How to treat hyperthyroidism in cats?
Many factors must be considered when choosing the best therapy for an individual cat. The treatment options for hyperthyroidism are: Surgery. Surgical removal of the affected thyroid gland (s) may be very effective.
How many surgeries are needed for thyroid disease in cats?
In many cats, only one thyroid lobe is abnormal, so only one surgery is needed.
How often should I monitor thyroid levels?
The required dose of methimazole can change over time so monitoring thyroid levels in treated animals is recommended every 3-6 months once their condition is stable. Radioactive iodine. A very effective way to treat hyperthyroidism is with radioactive iodine therapy (I-131).
What is the TT4 level in cats?
The first step is to determine the blood level of one of the thyroid hormones, called total thyroxine (TT4). Usually, the TT4 level is so high that there is no question as to the diagnosis. Occasionally, a cat that is suspected of having hyperthyroidism has a TT4 level within the upper range of normal.
Why does my cat get hyperthyroid?
Hypertension develops due to the increased pumping pressure and elevated heart rate that occurs with thyrotoxic cardiomyopathy. About 25% of cats with hyperthyroidism become hypertensive. In some cats, blood pressure can become so high that retinal bleeding or retinal detachment will occur, resulting in sudden blindness.
Why does my cat have a heart murmur?
Thyrotoxic cardiomyopathy may develop because the heart enlarges and thickens to meet the increased metabolic demands. In some cases, the cat will develop a heart murmur associated with the cardiomyopathy. Both cardiomyopathy and hypertension are potentially reversible with appropriate treatment of the disease.
Where is the thyroid in cats?
Some hyperthyroid cats have thyroid cells in abnormal locations called ectopic thyroid tissue (thyroid tissue located under the tongue, further down the neck, or all the way to the base of the heart) - and they may remain hyperthyroid after surgery.
What Is Hyperthyroidism?
Hyperthyroidism, the opposite of hypothyroidism, is also known as thyrotoxicosis and occurs when the thyroid gland becomes enlarged and produces extra hormones. The thyroid gland is located in the neck and makes hormones called T3 and T4, which play a role in a variety of bodily functions, including metabolism and body temperature regulation.
Causes of Hyperthyroidism in Cats
There are two types of tumors that cause hyperthyroidism in cats. Most cases of hyperthyroidism are due to a benign tumor called an adenoma but in rare cases, a cancerous tumor called an adenocarcinoma is the cause. Both tumors cause the thyroid gland to become enlarged but no one knows what causes either type of tumor to grow to begin with.
Diagnosing Hyperthyroidism in Cats
If your cat is showing symptoms of hyperthyroidism, a visit to their veterinarian is warranted. The vet will perform a physical examination and obtain your cat's history before recommending blood screening be performed. Sometimes, enlarged thyroid glands can be detected during the physical exam.
Treatment of Hyperthyroidism in Cats
There are four ways to treat a cat that has been diagnosed with hyperthyroidism: dietary treatment, surgery, medication, and radioactive iodine therapy. Each option has its pros and cons and may not be right for every cat but the majority of cat owners opt to treat the disease with either diet or medication.
How to Prevent Hyperthyroidism in Cats
Because no one knows what causes a cat to develop the tumors that cause hyperthyroidism, there is no way to prevent the disease. The best thing you can do as a cat owner is to address any symptoms of hyperthyroidism as soon as you see them. Additionally, treating the disease promptly upon diagnosis will help prevent other problems from developing.
Risk Factors for Hyperthyroidism in Cats
While no specific cat breed has a definitively higher risk for developing hyperthyroidism than another, any cat senior is at a greater risk for the disease. Some studies suggest that cats that eat mostly canned food, especially fish-based canned food, are at increased risk.
What is the condition of a cat with hyperthyroidism?
More than 80% of hyperthyroid cats have a condition known as 'hyperplasia' , resulting in excessive function and enlargement of both thyroid lobes. However, both lobes cannot always be felt, even if both are functioning excessively. About 15% of hyperthyroid cats have a benign tumor (adenoma), and usually only one of the two lobes is involved.
What are the symptoms of hyperthyroidism in cats?
What are the clinical signs of feline hyperthyroidism? The overproduction of thyroid hormone leads to a multitude of clinical signs, most commonly weight loss, increased appetite, increased activity and/or vocalization, vomiting, diarrhea, increased water consumption, and increased urination. Some cats show all of these signs, ...
What percentage of cats have thyroid cancer?
About 15% of hyperthyroid cats have a benign tumor (adenoma), and usually only one of the two lobes is involved. Approximately 2-3% of hyperthyroid cats have a carcinoma (malignant tumor) that can be variable in presentation, involving one lobe or creating multiple nodules. Some cats also have abnormal functional thyroid tissue located in the chest.
What is a cat's thyroid?
What Is Feline Hyperthyroidism? Feline hyperthyroidism is a common endocrine disorder in older cats, caused by the overproduction of thyroid hormone. Left untreated, hyperthyroidism can result in heart failure and other complications, and can even lead to death. The thyroid is a gland in the neck that produces hormones that regulate metabolism ...
How long does it take for a cat to be hospitalized after a thyroid scan?
Cats need to be hospitalized for 24-hours following this scan to prevent owner exposure to radiation.
What tests are needed for thyroid?
Laboratory tests include a minimum of kidney values (BUN and creatinine) and a urinalysis in conjunction with thyroid testing. Additional tests can be required if concurrent illnesses are detected on physical exam or blood work, and a technetium scan might be recommended.
Where is the thyroid gland in cats?
The thyroid is a gland in the neck that produces hormones that regulate metabolism and many other processes in the body. Cats have two thyroid lobes, one located on each side of the trachea (windpipe) in the neck. More than 80% of hyperthyroid cats have a condition known as 'hyperplasia', resulting in excessive function and enlargement ...
What was the first treatment for cat hyperthyroidism?
Initial cases were cats that had extreme weight loss in the face of a voracious appetite. Initial treatment was with thyroidectomy, later followed by medical therapy with PTU, which gave way to Methimazole. Shortly thereafter in 1981, Dr. Peterson used I-131 for the first time to treat a cat with hyperthyroidism.
How much methmazole should I give my cat?
Treatment is usually initiated at a dose of 2.5 mg per cat twice daily.
When was hyperthyroidism first diagnosed?
Feline hyperthyroidism was an unknown entity until 1978 when Dr. Jean Holzworth at Angell Memorial Animal Hospital in Boston first diagnosed it. In 1979, Dr. Mark Peterson, who had also recognized the disease at the Animal Medical Center in New York, gave the first lecture presentation on the disease.
How long does a cat stay in hospital after radiation?
Depending on the dose administered and the locale, the cat will need to be hospitalized for 5 – 14 days. Once discharged, there are also handling restrictions at home. Most of the emitted radiation stays with the cat, however some is excreted in the saliva and urine. For the first two weeks following discharge: 1.
How often should T4 levels be checked?
Heptopathy and facial pruritus (especially around the base of the ears) can also be seen. Hematology, chemistries, urinalysis and T4 levels should be checked every 2- 4 weeks initially and then less frequently as control is achieved. It is recommended that the T4 level be tested six hours post pill.
Can I-131 be given to cats?
2.5% of treated cats become hypothyroid and they may require thyroid supplementation. The other 2.5% remain hyperthyroid and frequently can be controlled with a second dose of I-131.
Can cats eat canned fish?
Cats eating mostly canned foods, especially canned fish, are at a higher risk. 2. Signaling agents – Cats with thyroid adenomatous hyperplasia have decreased levels of G protein in their thyroids, which may decrease cAMP inhibition of cell growth.
What does a veterinarian do for a cat with thyroid problems?
A veterinarian will complete a physical examination of a cat when one suspects him to have hyperthyroidism, taking into account any symptoms described. One of the exams consists of feeling a cat's neck. If the gland is big enough, a veterinarian will be able to feel the thyroid.
What is hyperthyroidism in cats?
Hyperthyroidism in cats is a common disorder that affects cats when their thyroid becomes overactive. This condition can be dealt with in a few different ways; surgery being a popular method of treatment.
What is it called when a cat's thyroid gland is enlarged?
Hyperthyroidism, also called thyrotoxicosis , occurs in cats that are middle-aged or older. It is an endocrine disorder caused by an increase in the hormones produced by a cat's thyroid. As a result, a cat's thyroid gland becomes enlarged.
What gland controls thyroid in cats?
The hormones produced, T3 and T4, are controlled by thyroid-stimulating hormones made by a cat's pituitary gland. The T3 and T4 hormones regulate many of the cat's vital systems, including his metabolism.
What hormones are produced in cats?
The T3 and T4 hormones regulate many of the cat's vital systems, including his metabolism. When too many T3 and T4 hormones are produced within a cat's body the thyroid gland develops adenomas, or small nodules, which are benign up to 98% of the time. Adenomas can form on one or both lobes of a cat's thyroid.
What happens if you remove a cat's thyroid?
Like all surgical procedures, complications may arise from the removal of a cat's thyroid. These complications include infection, the accidental removal of the pituitary gland, hypocalcemia, hypothyroidism, and paralysis of the larynx.
Can a veterinarian feel a cat's thyroid?
If the gland is big enough, a veterinarian will be able to feel the thyroid. A veterinarian will then have the cat's blood tested to see if there is an elevation in the T4 and T3 hormones, but he will particularly look at the T4 levels.
What are the disadvantages of thyroid surgery?
Additional Disadvantages and Potential Complications of Surgical Treatment 1 There is always a risk that abnormal thyroid tissues may inadvertently get left behind. If this happens, hyperthyroidism can recur within 6 to 24 months. 2 Pre and post-surgical monitoring is expensive. 3 If a cat's laryngeal nerve is damaged during surgery, the cat may experience a voice change that may be permanent. 4 Horner's syndrome may result. This syndrome is when nearby neurologic tissue is damaged. It causes a cat's eye to squint and draw back into the socket, the pupil will constrict and the third eyelid will come up. 5 Some cats develop hypothyroidism after surgery and must take supplementation tablets either temporarily or permanently
Why does my cat's eye squint?
It causes a cat's eye to squint and draw back into the socket, the pupil will constrict and the third eyelid will come up. It should be noted that there do exist unique advantages to surgery.
How long does it take for thyroid surgery to recur?
There is always a risk that abnormal thyroid tissues may inadvertently get left behind. If this happens, hyperthyroidism can recur within 6 to 24 months. Pre and post-surgical monitoring is expensive.
Is surgery considered permanent?
It should be noted that there do exist unique advantages to surgery. If no complications develop, surgery eradicates the need for further treatment as it is considered permanent. Also, no special facilities are necessary to pursue this treatment.
Causes
Pathophysiology
- Thyroid hormones affect nearly all of the organs in the body; therefore, thyroid disease often causes secondary problems.
Symptoms
- Clinical Signs Cats afflicted with hyperthyroidism usually develop a variety of signs that may be subtle at first but that become more severe as the disease progresses. The most common clinical signs of hyperthyroidism are weight loss, increased appetite, and increased thirst and urination. Hyperthyroidism may also cause vomiting, diarrhea, and hyperactivity. The coat of affected cats …
Diagnosis
- Diagnosis A veterinarian who suspects a cat has a thyroid problem will conduct a physical examination and palpate the cats neck area to check for an enlarged thyroid gland (see Figure 2). The cats heart rate and blood pressure may also be checked. If thyroid disease is a possibility, your veterinarian will likely order a blood chemistry panel and an analysis of thyroid hormone lev…
Results
- Radioactive iodine therapy is curative within three months of therapy in approximately 95 percent of all hyperthyroid cases. In cases where radioactive iodine therapy is not successful, the treatment can be repeated. Rarely, a permanent reduction in thyroid-hormone levels called hypothyroidism occurs after radioactive iodine treatment. If this is accompanied by clinical sign…
Benefits
- Removal of the thyroid glands, called surgical thyroidectomy, is a relatively straightforward surgical procedure that has a good success rate. The advantage of surgery is that it is likely to produce a long-term or permanent cure in most cats, and therefore eliminates the need for long-term medication.
Clinical significance
- Because of the important role the thyroid gland plays in the body, some cats with hyperthyroidism develop secondary problems, including heart disease and high blood pressure. Elevated thyroid hormones stimulate an increased heart rate and a stronger contraction of the heart muscle, and can cause thickening of the left ventricle of the heart over time. If left untreated and unmanaged…
Prognosis
- Hypertension, or high blood pressure, is another potential complication of hyperthyroidism, and can cause additional damage to several organs, including the eyes, kidneys, heart, and brain. If hypertension is diagnosed along with hyperthyroidism, drugs may be needed to control the blood pressure and reduce the risk of damaging other organs. As in the case of heart disease, after th…