In the vast majority of cases the increased thyroid hormone production is due to a benign (non-cancerous) change. Both of the thyroid glands are involved, although one gland may be more severely affected than the other. The abnormal thyroid tissue becomes enlarged, but the underlying cause of this change is currently unknown. Cats usually respond extremely well to treatment, and if the condition is recognised early and treated appropriately, then the outlook for the affected cat is generally very good.
A malignant (cancerous) tumour known as a thyroid adenocarcinoma can also be an underlying cause of some cases of hyperthyroidism. Fortunately this is rare, and is only the cause in around one to two per cent of all hyperthyroid cats. When a thyroid adenocarcinoma is present treatment is much more difficult.
Medical management (drug therapy)
Anti-thyroid drugs are available in tablet form and these act by reducing the production and release of thyroid hormone from the thyroid gland. They do not provide a cure for the condition, but they do allow either short-term or long-term control of hyperthyroidism. Methimazole (trade name Felimazole) is given at a starting dose of 2.5 mg twice daily. Thyroid hormone concentrations usually fall to within the reference range within 3 weeks. For long term management the dose of Felimazole is then adjusted according to response. To maintain control of hyperthyroidism, Felimazole needs to be given daily for the rest of the cat's life. Felimazole is the only licensed treatment for feline hyperthyroidism.
For most cats methimazole (or a related drug, carbimazole) is a safe and effective treatment for hyperthyroidism. Side effects are uncommon and if they do occur they are usually mild and reversible. Poor appetite, vomiting and lethargy are the most likely side effects and often resolve after the first few weeks of treatment and/or by temporarily reducing the dose of treatment and administering the tablets with food. More serious problems, including reduced white blood cell counts, reduced platelet counts (which help the blood to clot), liver disorders, or skin irritation are rare, but if they do occur then an alternative treatment must be used.
Anti-thyroid drug treatment has the advantage of being readily available and economical, but it is not curative. Life long treatment, usually involving twice daily oral dosage, will be required and for some owners, and some cats, this may be difficult to achieve. Routine blood tests should be checked periodically during treatment to monitor the effectiveness of therapy, to monitor kidney function (see above) and to look for potential side effects.
Surgical thyroidectomy
Surgical removal of the affected thyroid tissue (thyroidectomy) can produce a permanent cure and is a common treatment for many hyperthyroid cats. In general this is a very successful procedure and is likely to produce a long-term cure or permanent cure in most cats. However, even after successful surgery, occasionally signs of hyperthyroidism develop again at a later time if previously unaffected thyroid tissue becomes diseased.
To reduce anaesthetic and surgical complications, where possible it is always recommended that hyperthyroid patients are initially stabilised with anti-thyroid drugs for three to four weeks before surgery. Any associated heart disease must also be treated where necessary. Good success and avoidance of post-operative complications depend on good surgical skills, and experience is necessary to achieve good results. The major risk associated with surgery itself is inadvertent damage to the parathyroid glands – these are small glands that lie close to, or within, the thyroid glands themselves, and have a crucial role in maintaining stable blood calcium levels. Damage to these glands can result in a life-threatening fall in blood calcium concentrations (hypocalcaemia). This is most likely to occur when both thyroid glands are removed at the same time, since this can result in damage to both parathyroid glands. To minimise the risk of this complication in those cats that require removal of both thyroid glands it may be appropriate to perform the procedure in two stages, removing the most affected gland first and allowing six to eight weeks for recovery of parathyroid hormone production before removing the second thyroid gland.
It is usually recommended that cats remain hospitalised for a few days after surgery so that blood calcium concentrations can be monitored and any treatment given, if required. Clinical signs of low blood calcium include muscle twitches and weakness, which can progress rapidly to convulsive seizures. Treatment is with supplemental calcium by injection and then by mouth. Additional treatment with vitamin D3 is also needed to allow the calcium given by mouth to be used effectively. Once stable, continued treatment can be given at home, but in most cats the damage to the parathyroid glands is only temporary and treatment may only be needed for a few days or weeks.
Radioactive iodine therapy
Radioactive iodine (I 131) can also be used to provide a safe and effective cure for hyperthyroidism. Like surgical thyroidectomy, it has the advantage of being curative in most cases with no ongoing treatment required.
Radioactive iodine is administered as an injection given under the skin – the iodine is then taken up by the active (abnormal) thyroid tissue, but not by any other body tissues, resulting in a selective local accumulation of radioactive material in the abnormal tissues. The radiation destroys the affected abnormal thyroid tissue, but does not damage the surrounding tissues or the parathyroid glands.
The advantages of radioactive iodine are that it is curative, has no serious side-effects, does not require an anaesthetic and is effective in treating all affected thyroid tissue at one time, regardless of the location of the tissue. However, it does involve the handling and injection of a radioactive substance. This carries no significant risk for the patient, but precautionary protective measures are required for people who come into close contact with the cat. For this reason, the treatment can only be carried out in certain specially licensed facilities and a treated cat has to remain hospitalised until the radiation level has fallen to within acceptable limits. This usually means that the cat must be hospitalised for between three and six weeks (depending on the facility) following treatment. Most treated cats have normal thyroid hormone concentrations restored within three weeks of the treatment, although in some it can take longer.
A single injection of radioactive iodine is curative in around 95 per cent of all hyperthyroid cases, and in the few cats where hyperthyroidism persists the treatment can be repeated. Occasionally a permanent reduction in thyroid hormone levels (hypothyroidism) occurs following radioactive iodine treatment, and if this is accompanied by clinical signs (lethargy, obesity, poor haircoat) then thyroid hormone supplementation may be required (in the form of tablets).
The licensed facilities currently available in the UK are at the Animal Health Trust near Newmarket, the university veterinary schools at Bristol and Glasgow, and at the Barton Veterinary Hospital in Canterbury.
Treatment of thyroid adenocarcinoma
The rare cases of thyroid adenocarcinoma (malignant tumour) are more difficult to treat and the prognosis is always guarded. Some can be successfully treated using very high doses of radioactive iodine, whereas external beam radiation therapy (conventional radiotherapy) may be more appropriate for others. Where an adenocarcinoma is found or is suspected, careful treatment planning is required for best results.
2007-04-30 12:32:17
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answer #1
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answered by Unicornrider 7
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If all your cat has is hyperthyroidism, they can live a long and healthy life as long as you can treat the disease. There are three ways to treat it: oral medications, radioactive iodine treatment, and surgery. I'm not sure what you mean by "Chemo." Untreated, hyperthyroid cats will continue to lose weight and have other health problems.
Most vets start with the oral medication methimazole (aka Tapazole). This medication lowers the activity of the excess thyroid hormones in your cat's bloodstream, which prevents the signs of hyperthyroidism. It is not a cure and the cat will need to keep taking the medication indefinitely, unless you have one of the other treatments done. However many cats can do well with this treatment for rest of their lives, but there can be side effects.
Surgery is another method - this involves removal of the thyroid gland. It's not the best treatment since there are risks of disturbing the nearby parathryoid glands (they control calcium levels in the blood). If these glands are damaged, there can be potentially life-threatening side effects. Most vets no longer recommend surgery to treat hyperthyroidism.
The final method is by using radioactive iodine. This is the safest way to definitively cure the disease. The cat gets an injection of radioactive iodine. The iodine is only used by the thyroid gland, so there is no risk of damage to any other part of the body. The overactive part of the gland is destroyed. Most cats return to a normal thyroid level after treatment, although some with very high levels before treatment need more than one round. There are almost no side effects and most cats do great with this treatment.
The main drawback is cost and finding a location near you that does the treatment. I had this procedure done for my cat about a year and a half ago and he did great. The cat is radioactive for a period of time and will have to stay at the clinic for several days, followed by special handling at your home for a few weeks. You can search for Radiocat online, that's a national hospital chain that does this treatment (I had my cat's treatment done there).
Good luck!
2007-04-30 11:53:23
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answer #2
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answered by jhishar 1
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2016-12-22 22:41:44
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answer #3
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answered by Anonymous
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Depending on the general health and age of your animal it is absolutely ridiculous to out and out state to put a kitty to sleep. That other owner shouldn't have pets if they can dismiss a pet in that way.
I have a kitty who is 13 and I did go through the Radioactive Iodine Treatment (Chemo-like). It worked for him. I had another younger kitty with CRF at the same time and his treatment did not work for very long. It cost me a fortune and I am not rich. I do not begrudge one cent. I made him comfortable for as long as possible and I still have Niko.
The clinics that are regulated to provide the radiation treatment may be hard to locate, but most provide assistance in shipping transportation. The amount of radiation used is minimal and much less than what they give humans. They quarantine the pets, but this is only regulatory. And risk to children, pregnant woman etc... is over emphasized. They never quarantine peple. You get more radiation with a couple of airplane rides. You will need to gather their poop for a while and hold it in a five gallon bucket until the radiation subsides, again this is the regulation. Another alternative is to use a flushable litter, which I did not do because I live on the fifth floor and I want no change of causing draining issue.
The medicine to control hyperthyroidism is costly and has numerous side affects. It doesn't take too long for the cost to balance out between the two options and the chemo prevents all the hassle of medication as well.
I have heard of a surgery option, but my vet didn't even discuss it as a practical solution. The risks are too high.
Bottom line, chemo ends up being more effective, less harmful, less hassle and less costly for most kitties as their survival rate is increased. I think the delta is about 9 months.
2007-04-30 11:54:24
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answer #4
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answered by Sliwa 1
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The primary treatment for hyperthyroidism is usually control with medication. Surgical removal of the thyroid gland and radioactive iodine therapy may be indicated if the cat is younger and otherwise healthy, like in the early stages of the disorder.
If you have a cat with hyperthyroidism, your vet is the best person to speak to about appropriate treatment. If you'r looking for natural remedies (I've never heard any suggestions) you'll find that most vets will at least discuss them even if they don't support them - which some do.
Chalice
2007-04-30 12:29:35
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answer #5
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answered by Chalice 7
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My cat Larry had hyperthyroidism. It became quite severe and he lost a signifiant amount of weight and stopped eating much because of the disease. He was one of the first cats to get the surgery you are talking about which was pioneered by his vet in the Chicagoland area. It saved his life. He was already very old (about 20) when he had the surgery and lived another 6 years afterward in relatively good health. A few weeks after I brought him home from the pet hospital, he was near his old self again. That surgery was expensive but worth every penny. Before the surgery, we tried drug treatment for him. He absolutely would not take straight pills. The solution we came up with was processed cheese. We would take some and mold it around the pill. He loved the stuff and cats don't chew food much. This worked most of the time, although he would occassionally lose the pill (I'd find it on the floor later). One thing I considered doing but never tried (medication wasn't working so I took him for surgery) was grinding the pill into a powder. This is easy to do with a $10 coffee grinder (only use the grinder for his medication and nothing else, hehe). It will pulverize the pill into a fine powder. Then, mix the powder with some food he likes (cheese is good because stuff sticks to it).
2016-05-17 13:04:58
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answer #6
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answered by Anonymous
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I just had my family cat of 16 years pass away on Saturday from a combination of hyperthyroidism and kidney failure (the two were linked). If caught early enough, radiation therapy (I don't think its chemo exactly) can work wonders. If its not, then there is medication that keeps it in check, but unfortunately not for long. As it was explained to me by our vet, the hyperthyroidism causes the blood to move faster through the kidneys, and they basically go into overdrive, causing kidney failure (this is what happened to our cat).
If it is your kitty that has this, then I'm very sorry. I wish I had better news for you.
2007-04-30 11:54:59
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answer #7
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answered by Audrey A 6
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Time to put kitty to sleep... Let go, you can't hurt your own finances and sanity for the sake of a cat. I have had many pets, if you try to keep one going, it is going to be harder and harder to finally let go.
Get a new kitten in a year, and move on.
Sorry to be so harsh, but I have been on both sides. I spent money, years and sanity trying to keep a pet alive, and it was soooo stressful.
2007-04-30 11:41:43
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answer #8
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answered by Anonymous
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put the cat on thyroid pills...why is your vet suggesting chemo???
2007-04-30 14:43:22
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answer #9
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answered by Anonymous
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