The most common antithyroid drugs used for felines include:
- Methimazole also known as felimazole, which can be administered once or twice per day, depending on the condition of the...
- Cabimazole also known as vidalta, which should be given once per day; it is important not to break or crush the tablets...
When to put a cat to sleep 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 cats be on tapazole?
The majority of cats respond to treatment within weeks, although some may take up to six months to fully benefit from it. It is possible, however, that a very small number of cats do not have this problem. The hyperthyroid status of cats treated with radio-iodine will remain the same for 6 months after treatment.
Can cats live with hyperthyroidism?
There is no “one size fits all” scenario here. It is quite possible for a cat to lead a reasonable life with hyperthyroidism as long as this is the only medical condition they’re dealing with. Unfortunately, as a cat begins to grow older, it will have other medical concerns pop up.
Why do cats get hyperthyroidism?
Hyperthyroidism results when the thyroid gland over-produces thyroid hormones. The disease is common in cats and negatively affects almost all body organs. Felimazole Coated Tablets (methimazole ...
What is the best medication for hyperthyroidism in cats?
Only one drug, Felimazole Coated Tablets (methimazole), is FDA-approved to treat hyperthyroidism in cats. Approved by FDA in May 2009, Felimazole contains methimazole as the active ingredient.
Is there an alternative to methimazole for cats?
Another approach for cats who cannot take methimazole involves a combination of potassium iodate and a heart medication called “propranolol.” Potassium iodate blocks the thyroid gland's uptake of iodine.
What medication is given to cats with thyroid problems?
The most common medication prescribed to treat feline hyperthyroidism is called methimazole (trade name Tapazole or Felimazole). This medication has virtually replaced the older medication propylthiouracil or PTU because methimazole is effective without as much tendency for side effects.
What is the treatment for a cat with hyperthyroidism?
A very effective way to treat hyperthyroidism is with radioactive iodine therapy (I-131). When an injection of radioactive iodine is given, it destroys the abnormal thyroid tissue without endangering other organs. I-131 therapy does not require anesthesia, and it eliminates the need for daily medication.
What is the difference between Felimazole and Tapazole?
Methimazole (brand names: Tapazole®, Felimazole®) is an antithyroid medication used to treat hyperthyroidism in cats. Its use in cats and guinea pigs to treat hyperthyroidism is occasionally 'off label' or 'extra label'. Many drugs are commonly prescribed for off label use in veterinary medicine.
When is the best time to take methimazole 5mg?
To make sure that you always get the same effects, try to take methimazole at the same time in relation to meals every day. That is, always take it with meals or always take it on an empty stomach.
What is the difference between Felimazole and methimazole?
Oral tablets Felimazole is an FDA-approved methimazole tablet just for cats. It's available as 2.5 mg and 5 mg tablets. Before it was approved in 2009, human methimazole tablets were used in cats. This is considered off-label, which means they were used in a way that isn't FDA-approved.
How Long Can cats live on methimazole?
When cats with preexisting renal disease were excluded, median survival time for cats treated with methimazole alone (2.0 years; interquartile range [IQR], 1 to 3.9 years) was significantly shorter than median survival time for cats treated with 131I alone (4.0 years; IQR, 3.0 to 4.8 years) or methimazole followed by ...
How much methimazole should I give my cat?
Initially, methimazole is given at a dose of 2.5 mg to 5 mg per cat, once to twice daily. The ideal administration is 2.5 mg every 12 hours. Methimazole transdermal dosage is often 2.5 mg to the inner ear pinna every 12 hours. Gloves should be used by the owner when administering this medication.
What is the life expectancy of a cat with hyperthyroidism?
What is the prognosis for cats diagnosed with Feline Hyperthyroidism? If effectively managed, cats with hyperthyroidism can live for many years with a very good quality of life. If untreated, this disease will cause uncontrolled weight loss, severe heart disease and eventually death.
What are the side effects of methimazole in cats?
The most common side effects include vomiting, anorexia, and tiredness, and usually occur within the first three months of treatment. Other, less common side effects such as gastrointestinal effects and mild changes in your pet's blood cell counts are usually temporary and resolve with time.
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.
What is the best medication for hyperthyroidism in cats?
Anti-thyroid drugs (e.g., methimazole, carbimazole) are commonly used for treatment of hyperthyroidism in cats. 14-21 If administered appropriately, they reliably inhibit the synthesis of thyroid hormones and thereby lower serum thyroid hormone concentrations. These drugs do not affect the thyroid gland's ability to trap inorganic iodide or release preformed hormones. They are widely recommended to stabilize hyperthyroid cats prior to surgery and are the only drugs that can be used chronically for management of hyperthyroidism. 6 Almost all cats are potential candidates unless thyroid carcinoma is suspected.
How long does it take for a cat to become euthyroid?
All should be discussed with pet owners, including pros/cons, so that the best option can be selected for individual patients and their owners. Feeding a limited-iodine food is now available as an option for effective management of hyperthyroid patients. When fed as the sole source of nutrition, approximately 90% of hyperthyroid cats become euthyroid within 4 to 12 weeks. To date, over 150 cats with naturally occurring hyperthyroidism have been managed successfully by feeding a limited-iodine food, most for 2-3 years and some cats for as long as 6 years.
What is the iodine content of cat food?
Iodine occurs naturally in many ingredients typically used in the manufacture of commercial pet foods (particularly fish, shellfish and fresh meats) and unless steps are taken to strictly control the iodine content of ingredients, the final iodine concentration in pet foods varies widely. 22-25 Commercial cat foods in New Zealand had iodine amounts ranging from 0.19 to 21.2 ppm in one study whereas in Germany a range of 0.22 to 6.4 ppm was reported.22,26 Evaluation of 28 canned cat foods in the US revealed an iodine content ranging from 1.09 to 52.3 ppm (mean = 7.83) and 14 dry cat foods contained iodine amounts ranging from 1.34 to 5.94 ppm (mean = 2.77). 25 Based on these studies, the amount of iodine is much higher in many canned foods compared with dry foods and variability of iodine content is much greater in canned food. 22,25-26
What is the T4 level in cats?
Diagnosis most often is based on the presence of one or more typical clinical signs and increased serum total thyroxine (T4) concentration. However, up to 10% of all hyperthyroid cats and 40% of those with mild disease have serum T4 values within reference range 1,2 The diagnosis of hyperthyroidism should not be excluded on the basis of a single normal serum T4 value, especially in a cat with typical clinical signs, a palpable thyroid nodule and serum T4 in the upper half of the normal range. 3 In these cases, serum free T4 (fT4), measured by equilibrium dialysis, may provide an alternative means of diagnosing hyperthyroidism in cats with normal serum total T4 values. Studies document that up to 20% of sick euthyroid cats can have increased fT4 concentration.4 Therefore, it is most appropriate and reliable to interpret the two values together. Mid-to-high reference range total T4 and increased fT4 concentration is consistent with hyperthyroidism. In contrast, low total T4 and increased fT4 values are usually associated with non-thyroidal illness.
Does iodine help with thyroid in cats?
The only function for ingested iodine is for thyroid hormone synthesis.5 This observation led to the hypothesis that limiting dietary iodine intake could be used to control thyroid hormone production and potentially manage hyperthyroidism in cats. After more than a decade of research and development, a limited-iodine therapeutic food (Hill's® Prescription Diet® y/dTM Feline) containing < 0.3 ppm (mg/kg) iodine on a dry matter basis (DMB), is now available as an option for managing cats with hyperthyroidism.
Can cats with CKD have CKD?
Chronic kidney disease (CKD) and hyperthyroidism are more likely to be diagnosed in older cats so it's not surprising that many hyperthyroid cats have CKD. Untreated hyperthyroidism complicates the diagnosis of CKD because it's associated with increased glomerular filtration rate (GFR) and therefore often masks biochemical markers of CKD. Regardless of the therapeutic modality (methimazole, surgical thyroidectomy, or radioiodine), decreased GFR, increased serum urea and creatinine concentrations and development of overt clinical signs of kidney disease have been reported after successful treatment of hyperthyroidism.4,33-36 The presence of underlying CKD may affect the prognosis - one study documented a shorter survival time in hyperthyroid cats with azotemia. 7 However, two recent studies comparing survival of cats that developed azotemia with those that did not after treatment of hyperthyroidism found no significant difference between the two groups if cats did not become hypothyroid post-treatment.38,39
What is the best treatment for 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.
What is the procedure to remove a cat's thyroid gland?
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.
How long does radioactive iodine therapy last?
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.
How long does it take for a cat to get iodine?
The majority of cats treated with radioactive iodine have normal hormone levels within one to two weeks of treatment. The advantages of radioactive iodine therapy are that the procedure most often cures hyperthyroidism, has no serious side effects, and does not require anesthesia.
How do anti-thyroid drugs work?
Medication. Anti-thyroid drugs act by reducing the production and release of thyroid hormone from the thyroid gland. These medications do not provide a cure for the disease, but they do allow either short-term or long-term control of hyperthyroidism.
How do you know if your cat has hyperthyroidism?
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.
What are the side effects of taking medication on cats?
Some cats may experience side effects from medication, however, including vomiting, anorexia, fever, anemia, and lethargy.
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.
How to treat hyperthyroidism in cats?
One treatment option for cats with hyperthyroidism is the administration of methimazole, which lowers the amount of thyroid hormone produced by your cat’s thyroid gland. This medication must be administered to your cat for the remainder of its life. Methimazole is usually prescribed as an oral tablet. For those whose cats are less than cooperative for pilling, veterinary compounding pharmacies can formulate methimazole as a transdermal gel that gets applied topically to the inside surface of the cat’s outer ear.
How does iodine help cats?
Iodine plays an essential role in thyroid hormone production, and your cat gets iodine from its food. Prescription diets that are low in iodine help to reduce the level of thyroid hormone produced. These diets are available only from your veterinarian, who may prescribe the dietary management alone or to supplement the use of methimazole so that a lower dose of the medication may be needed. Hills Prescription Diet y/d is available in canned and dry variations, and it is formulated to also support renal health and heart health.
Can a cat have a thyroid problem?
Hyperthyroidism, a condition that is defined as an overactive thyroid gland, is one of the most common health conditions to affect senior cats. Left untreated, hyperthyroidism will adversely affect your cat’s blood pressure and kidney health, and it can result in congestive heart failure. If your cat has been diagnosed with hyperthyroidism, there are several options to consider when it comes to treating your cat’s condition.
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.
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.
Can a cat have a T4 level?
As cats age, T4 levels in cats without hyperthyroidism tend to decrease into the low normal range. In a cat with clinical signs of hyperthyroidism and a high normal T4 level, then a free T4 (FT4) is indicated to further define the diagnosis.
Why is the specific gravity of cat urine less than 1.030?
Urinalysis results are variable, although the urine specific gravity may be less than 1.030 due to primary polydipsia or inability to concentrate the urine due to hyperthyroidism. Management of Group 1 cats consists of treatment for their hyperthyroid disease (see pages 406–410).
Can you do in-clinic thyroid testing at the same lab?
If in-clinic testing is performed for geriatric screening and significant changes are noted in thyroid hormone levels, obtain confirmatory testing at a reference laboratory.
Can a cat develop hypothyroidism?
FACT: Cats can develop clinically significant hypothyroidism even if the T4 is within the reference interval.
How does Methimazole work for cats?
Methimazole is the most commonly recommended treatment. This drug works by interfering with the thyroid’s ability to make thyroid hormone. It is given either orally, or is absorbed through the skin (usually applied to the ear). While this drug is generally well tolerated, it can cause vomiting and lethargy in a subset of cats. On occasion, there are some cats that don’t respond to the Methimazole at all. Over the ten years that I have been practicing, I have seen this a handful of times, including with my own cat.
What is the most common hormonal imbalance in senior cats?
Hyperthyroidism is the most common hormonal imbalance in senior cats. This occurs when the thyroid gland becomes enlarged and produces more thyroid hormone. The excessive amount of thyroid hormone causes weight loss, increased liver enzymes, vomiting, heart disease, and excitability/anxiety.
Why does my cat have kidney problems?
This occurs because the overactive thyroid hormone increases blood flow to the kidneys. When hyperthyroidism is treated, and blood flow returns to normal, the true kidney function is uncovered. Kidney disease is very common in older cats, and therefore most hyperthyroid cats have some degree of kidney disease as well.
Can cats eat diet therapy?
This diet therapy can work, but has a couple of limitations. The palatability is poor, and many cats will not eat the diet. It can only work if it is the sole diet given, no other treats or foods allowed. Even a few bites of another food would exceed the iodine restriction threshold.
Is iodine therapy considered a gold standard?
Iodine therapy has many advantages, and is considered the gold standard for treatment. I usually recommend this option as first line therapy. It is generally performed at a specialized facility, and involves only one treatment of iodine (I-131).
Do you have to take blood tests on cats?
One set of follow up blood tests are required, and most cats are then cured for life! Pros: One treatment is almost always curative, and no daily medication is required. It is extremely non-invasive, and you will not have to medicate your cat twice daily for the rest of their lives.
Can a cat's kidneys rise?
Once treatment begins, expect that your kitty’s kidney values will rise. It is important to understand that the kidney disease was not caused by the treatment but, instead was present all along. You can learn more about my holistic approach to kidney disease here.
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…
Treatment
- Treatment There are four treatment options for feline hyperthyroidism: medication, radioactive iodine therapy, surgery, and dietary therapy. Each treatment option has its advantages and disadvantages. The treatment a cat receives for hyperthyroidism will depend on specific circumstances, including the patients overall health status, the owners abi...
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…