Design and methods: Five hundred and four patients over 40 years of age with diffuse toxic goiter were treated with MMI for 18 months. This is why one of the first signs of thyroid disease may be a change in weight weight gain if the thyroid is underactive and weight loss if the thyroid is overactive. Generally, about 5 to 10 pounds of excess weight can likely be attributed to the lack of thyroid hormones that occurs in people diagnosed with hypothyroidism. The radioactive isotope, Iodine-131 ( 131 I), is administered as a one-off injection. Fewer than 2% of hyperthyroid cases in cats involve malignant thyroid gland tumors. The routine stay in our radioactive iodine unit is currently 12 days. To help your cat gain weight, you need to increase the protein and . One study looked at patients with Graves' disease who were treated with RAI over five years. Risks from hyperthyroidism. Hyperthyroidism is a common condition in older cats. Too cold? The three ways that we control exposures to external sources of radiation are time, distance, and shielding. Since hyperthyroid cats are usually over eight years of age, there is a degree of risk involved. Usually this means that the cat will need to be hospitalized for between three and five days after treatment. When x-rays, or any ionizing radiation, pass through the body they cause electrons to be ejected from atoms, leaving behind positive ions. The advantages of radioactive iodine therapy are that the procedure most often cures hyperthyroidism, has no serious side effects, and does not require anesthesia. The radioiodine (I-131) used to treat thyroid disease in people and animals emits both gamma rays and beta particles. Only certain facilities perform this procedure, which consists of giving your cat a shot of radioactive iodine, which gets rid of abnormal thyroid cells without harming normal ones. Ultimately of course, these conditions can be diagnosed. Milner R.J., Channell C.D., Levy J.K., et al., Survival Times for Cats with Hyperthyroidism Treated with Iodine 131, Methimazole, or Both: 167 Cases (1996-2003). NRC Regulations Learn more about the Clinical Nutrition Team at Tufts. If possible, I would like to wear protective clothing so we can return to our familiar habit of living/sleeping in 24-hour close physical contact to minimize his stress and promote his recovery. You may gain weight after you undergo radioactive iodine treatment. Often, treating hyperthyroidism will unmask hidden kidney failure that will require additional care and is best detected early in the course of the disease. Let's tackle the external exposure first as it is the simplest concept. Treatment for hypothyroidism in cats is . Not all veterinary facilities perform the procedure. Answer posted on 30 March 2019. Risk of Ionizing Radiation Exposure to Children: A Subject Review. Surgical removal of the gland under general anesthetic was another option. She has spoken at national and international conferences and a Capitol Hillbriefing, and is an expert in pet obesity, nutrition communication, and in the human-animal bond. The more common symptoms are an increase in thirst, urination, and appetite, as well as weight loss. 4. Did You Know? Discuss these issues with your veterinarian when considering dietary iodine restriction as a treatment for hyperthyroidism in cats. Surgery or radioactive iodine therapy to regulate overactive hormone production can sometimes leave cats with the opposite problem: their levels of thyroid hormone are now too low. Before deciding the form of treatment, several tests are performed, including additional blood tests, a urinalysis, chest radiographs (X-rays), an ECG, and blood pressure measurements. Finally, thyroid hormone has a role in kidney function and blood flow that may result in either directly damaging the kidney or obscuring underlying kidney disease that your cat may already have. The AVMI radioactive materials license utilizes release criteria and precautionary instructions specifically based on the evaluation of the relative exposure levels to clients following radioiodine therapy for hyperthyroid cats treated with I-131. Will he come around at some point or have we created a monster who will run off to the food dish every time we get up from the chair. Radioactive iodine therapy offers a cure through a simple injection that returns thyroid function to normal levels. Blog written by Dr. Daisy Spears in conjunction with Dr. Linder. The injection has no direct side effects. Studies show that weight gain is inevitable after radioiodine-induced hypothyroidism. I am certain that your veterinarian probably told you to take care when handling the litter and to wash your hands thoroughly after handling litter, the cat, and items that the cat came into contact with. For some cats, a veterinary therapeutic diet low in iodine may be all thats required to control symptoms. Giving him medication once or twice a day isn't an option, although if it's a medication that can be mixed in with his food, it's something you could discuss with the veterinary staff at the facility. These positive ions, or free radicals, can cause damage to DNA. Before treatment he was ravenous and losing weight -- typical of cats with that disorder I'm told. Over time, this progresses to increased blood pressure, severe weight loss, heart disease, blindness, and kidney damage. Weight change was analyzed in only 228 patients and 84% gained weight by 1 year after radioactive iodine therapy. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. The treatment of choice for hyperthyroid cats is radioactive iodine therapy, which is a cure. Hypothyroidism, is a condition resulting from a deficiency of thyroid hormone. Most cats respond to treatment within weeks, although some take up to 6 months to gain the full benefit. For this prescription diet to work, it must be the only food fed, which means no cheating with treats. Gradual weight gain and return to healthy body condition are expected. 2000-2023 TheCatSite.com. This I131 injection accumulates in the abnormal thyroid tissue, and the radioactivity kills the abnormal tissue without harming other vital structures nearby. Because metabolism is altered in hyperthyroidism, it's important to monitor your cat's weight and muscle mass. Radioactive iodine is a treatment for an overactive thyroid gland. . Cats receive a single dose of radioactive iodine by either subcutaneous injection or by a capsule given by mouth. She gained and ate a lot and we were more than happy. The good news is that virtually every client will already take steps to avoid this, even when radioactive iodine in their cat's urine is not the motivation. You'll need to consider whether to have radioactive iodine (RAI) vs. other treatments for hyperthyroidism and Graves' disease (an immune system disorder that can cause hyperthyroidism). A seven hour airplane trip exposes passengers to 0.02 mSv of radiation, which is a fraction of the exposure of a standard Chest x-ray (0.1 mSv). Thyroid scintigraphy may also be recommended to confirm a diagnosis and determine the size of the organ before surgery or radioactive iodine. Currently, there's only one FDA approved medication to treat feline hyperthyroidism called methimazole. The brand name of methimazole is called Felimazole. The dosage may vary but typically a cat is given this oral medication twice a day, every 12 hours. . Dr. Freeman has received research or residency funding from, given sponsored lectures for, or provided professional services for Aratana Therapeutics, Elanco, Guiding Stars Licencing Co LLC, Hills Pet Nutrition, Nestl Purina PetCare, P&G Petcare (now Mars), and Royal Canin. These statistics are averages and do not predict what is going to happen to you. Radioactive iodine therapy is curative within three months of therapy in approximately 95 percent of all hyperthyroid cases. If you can't bear to be away from him, or if he becomes very stressed or frightened when you're not around, that isolation could be difficult. It has the advantage of being curative in most cases with no ongoing treatment. Due to the damaging effects of hyperthyroid-induced hypertension on your cats kidneys, blood kidney values must be reassessed once the thyroxine level has normalized, even if they were normal on initial blood tests. Some people also feel flushed. Overall, weight gain was associated with development of hypothyroidism despite levothyroxine replacement . Radioiodine treatment avoids surgery, anesthesia, and anti-thyroid drugs. Symptoms include weight loss, muscle wasting, increased appetite, increased thirst and urination, vomiting, unkempt appearance, and sometimes hyperactivity. If both thyroid glands require removal, there is a risk of developing hypocalcemia (low blood calcium levels) after surgery. Rarely, people can feel pain in their neck. Dietary restriction of iodine is, however, somewhat controversial because of concerns about the effects of long-term iodine restriction on overall health and the possibility that such a diet may actually backfire and worsen hyperthyroidism. Weight seemed to stabilize in the long-term setting, with minimal increases between 8 and 12 months and at 24 months after radioactive iodine treatment. This may take 8 to 12 weeks or longer. Subpart D-Radiation Dose Limits for Individual Members of the Public It is also common for some cats to hide under the bed for a day or so after returning home as they de-stress following their out of home experience. There are currently no known preventive measures for hyperthyroidism, but early diagnosis decreases the secondary problems and improves the prognosis. Secondary Problems Long-Term Follow-up of Hyperthyroid Cats Treated with Iodine-131. When an injection of radioactive iodine is given, it destroys the abnormal thyroid tissue without endangering other organs. He also can't sleep with you during that time, and the facility will inform you about special arrangements you'll have to make for disposing of his litter. The advantages of radioactive iodine therapy are that the procedure most often cures hyperthyroidism, has no serious side effects, and does not require anesthesia. Also, I wonder if there is home-testing equipment to track the household dispersal of the radioactive contaminants that he emits after his treatment and something else to monitor and determine my exposure to the 131I remnants. . How does airline travel expose me to radiation? Hyperthyroidism is a common condition in older cats because of an excess of circulating thyroid hormone, called thyroxine. The thyroid gland, located in the neck, is responsible for the bodys metabolism. Is radioactive iodine treatment safe? Keeping your pets food temperature just right. The treatment a cat receives for hyperthyroidism will depend on specific circumstances, including the patients overall health status, the owners ability and willingness to medicate the cat regularly, and financial considerations. The "radiation badge" worn by x-ray techs for example is good for measuring external exposure to radiation but does nothing to measure intakes of radioactive materials which is the primary concern in the case of a cat treated with radioactive 131I. It might not be an option for a frail cat who shouldn't undergo anesthesia. For this long-term treatment, the cat is injected with the radioactive iodine, which destroys the tissue of the overactive thyroid gland. Nera just had her 3 month checkup and her T4 level is down to 2.3! It requires two round-trips for you. 197(2): p. 125-136. 15(1): p. 47-51. The radioiodine is eliminated in urine and feces. A large study found an increase in some cancer types in people who had radioactive iodine treatment for hyperthyroidism compared with the general population. The slow onset of signs means that cat owners will often miss these changes until the late stages of disease. Affected cats produce too much thyroid hormone. For the first two weeks after I-131: Keep your cat indoors or supervised when outside to prevent contact with other people. Did she have stage 1 prior to treatment for hyperthyroidism or did the stage 1 unmask after treatment started and then jump to stage 4? Slater M.R., Geller S. and Rogers K., Long-Term Health and Predictors of Survival for Hyperthyroid Cats Treated with Iodine 131. Affected cats are often restless and may become cranky or aggressive. When available, radioactive iodine therapy is the treatment of choice for cats with hyperthyroidism. What is taken up by the thyroid will be released slowly over the next days/weeks to the other bodily fluids which is why they have the precautions that you describe. Vet Rad & Ultrasound, 1994. People may take RAI . Although it has a slightly higher iodine content than the previous option, Tiki Cat Hanalei Luau Wild Salmon is the best value for money. Because the thyroid needs iodine to produce hormones, the thyroid takes the radioiodine into the thyroid cells and the radiation destroys the overactive thyroid cells over time. After administration of 131 Iodine, your cat is . You would actually have to ingest the cats waste for it to be harmful to you. In order to produce thyroid hormone (thyroxine), the body needs a supply of iodine. The iodine is taken into the thyroid gland and incorporated into thyroxine. This helps us offset the costs of running this site, so thank you for your support! Nuclear Medicine Patient Issues Questions Concerning Domestic Animals. Medication typically. 8. No individual breed is known to have a greater risk, although Siamese, Burmese, Persian, Abyssinian, Tonkinese, and British shorthair breeds appear to have a somewhat decreased incidence of hyperthyroidism compared to other breeds. Radioactive iodine therapy is a very effective way to treat hyperthyroidism (I-131). The study followed people for 26 years after two or more treatments. In some of these cats, blood pressure can become so high that retinal bleeding or retinal detachment will occur, resulting in sudden blindness. Miles K.G., Simpson S.A., Zimmerman R.B., et al. Regardless of radiation exposure, the average overall lifetime risk of developing an invasive cancer is 37.5% for women and 44.9% for men. What may work for one cat may not work for another. Both cardiomyopathy and hypertension are potentially reversible with appropriate treatment of the disease. The current Nuclear Regulatory Commission radiation dose limits for individual members of the public are listed below. There are virtually no side effects, and there is no pain associated with 131I treatment. What are other nutritional concerns for my hyperthyroid cat? Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society. Many owners of cats with hyperthyroidism are hesitant to have radiation therapy or surgery because of their cat's advanced age. The estimates of risk currently used are extrapolated from patients that have received much higher doses (e.g., atomic bomb survivors) using the linear, no-threshold model of radiation exposure risk. These medications do not provide a cure for the disease, but they do allow either short-term or long-term control of hyperthyroidism. Montreal. Therefore if you adhere to the release instructions we provide you with (copies provided on admission and again at discharge), you should be assured of getting less than 1 mSv exposure from interacting with your cat. As with surgery, you may need to take thyroid hormone . Hyperthyroidism, or an overactive thyroid, is a common disease of older cats. Because of strict treatment guidelines, most facilities will not allow visitors during this quarantine period. The cell dies (only occurs with very high doses). While my facility does not treat cats with radioactive 131I, I have consulted with a veterinary medicine program at a nearby university that does perform these types of procedures to get myself in the "cat-patient" mode of thought. Anti-thyroid drugs act by reducing the production and release of thyroid hormone from the thyroid gland. A single injection is given subcutaneously (i.e. In many cats, only one thyroid lobe is abnormal, so only one surgery is needed. Most cats with uncomplicated hyperthyroidism will live several years following treatment of hyperthyroidism, unless they develop another disease. Affiliate of Mars Inc. 2023 | Copyright VCA Animal Hospitals all rights reserved. Supporting Cat Health with Information and Health Studies. Research into this potential treatment option is ongoing. Of course, some people receive no radiation and others much, much more. Hyperthyroidism in cats is a commonly diagnosed endocrinopathy with an overall prevalence of 2.4% in England which increases to 8.7% in cats aged 10 years or older. The treatment options for hyperthyroidism are: Oral medication. Upon discharge from PVESC (after an average of 4 to 7 days after treatment), treated cats will still be excreting radioiodine in their urine, saliva, and feces. Most cats with hyperthyroidism have elevated levels of the thyroid hormone T4 in their bloodstream, but a small percentage of cats with hyperthyroidism have T4 levels within the normal range. Aim: Analysis and follow up of body weight after radioiodine therapy (RITh) of hyperthyroidism, since excessive weight gain is a common complaint among these patients. Radioactive iodine may also affect a woman's ovaries, and some women may have irregular periods for up to a year after treatment. Depending on the dose of radioactive iodine chosen, and the disease under treatment (Grave's vs toxic goitre, vs hot nodule etc), success rate in achieving definitive resolution of the hyperthyroidism . under the skin, like a vaccine) and the radioactive iodine is quickly absorbed into the bloodstream. As youre on this website right now, we can assume that you love pets and likely have a special dog or cat (or many) in your life. Additionally, diet may play a significant role in managing the disease, whether as a sole treatment or as an adjunct tool to address changes in your cats body related to hyperthyroidism. First we need to put this exposure level into some context: How do x-rays increase your risk for cancer? Why is the average risk of developing cancer so high? However, because your cat will be radioactive for several days after receiving the shot, precautions must be taken during and after the treatment. If the total GFR is below this number, medical therapy for hyperthyroidism may be recommended, although I-131 treatment may still be an option in specific patients. During treatment, radioactive iodine is administered as an injection and is quickly absorbed into the bloodstream. Interestingly, when higher doses are given, like those received by the patient treated for hyperthyroidism or thyroid cancer, then the injury to the cells is terminal and hence the cells do not survive to go on to become malignant. Diagnosis of feline hyperthyroidism is generally straightforward. If this is the case with your cat, paying special attention to specific nutrients such as dietary phosphorus (a key player in chronic kidney disease) may be required. A treated cat has to remain hospitalized until its radiation level has fallen to within acceptable limits. 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. The 1-month level thyroid may be slightly high, low or normal. Depending on the dose, radioactive iodine can kill a portion, or all, of your thyroid. As stated above, it may also be used for a few weeks to stabilize a cat at increased surgical risk because of cardiac complications. 2004. The information posted on this web page is intended as general reference information only. 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). Natural background radiation exposure accounts for an average of 3.1 mSv/yr with variations depending on where you live. This surgery requires general anesthesia, however, and there might be added risks if older cats have heart, kidney, or other problems that could cause complications. One of the reasons the cat was held for four days was to allow for much of the radioactive 131I to be excreted in urine so that the amount of external radiation exposure is significantly reduced. ), family history (genetics) or radiation exposure. A medication called methimazole, which interferes with thyroid hormone production, is less expensive but requires daily administration. If your cat requires daily medications for issues other than hyperthyroidism, he's not a candidate for radioactive iodine therapy. What are the risks of my cat becoming hypothyroid? Their hyperthyroidism won't come back, and they don't need ongoing medication. Radioactive iodine therapy offers a cure through a simple injection that returns thyroid function to normal levels. When this occurs, a second test, usually afree T4 by equilibrium dialysis (FT4 by ED)or aT3 suppression test,is performed. Clinical signs include lethargy, dullness, obesity, oily skin, and matted fur. Follow up blood work is essential to ensure kitty does not become hypothyroid which is too little thyroid. The only method to estimate that dose is to measure the radioiodine within your own thyroid and the types of equipment to measure that uptake are very expensive and difficult to interpret. Facilities that use radioactive materials like I-131 must have radioactive materials licenses. Why? This means that in order for this diet to work, your cat must eat the therapeutic diet exclusively and cannot eat any treats or supplements that might contain iodine and allow the thyroid gland to continue to make thyroxine. 101(4 Pt 1): p. 717-9. Lifelong treatment, usually involving twice-daily oral dosage, will be required, and for some owners and cats, this dosage schedule may be difficult to maintain. He rejected the Fancy Feast stuff and gobbled the baby food along with eating a little variety of the many dry foods we tried in an effort to find one that he really liked. Hyperthyroid cats are also at risk for complications related to the hypertension that frequently accompanies hyperthyroidism. Cats exclusively fed the prescription diet will remain normal, but if the diet is discontinued, they will once again become hyperthyroid. Weigh the pros and cons of various treatments and discuss options with your vet. Wet food is much better for him anyhow, so this is a good time to get him settled on it. However, because your cat will be radioactive for several days after receiving the shot, precautions must be taken during and after the treatment. Treatment usually requires one or two weeks of hospitalization at a veterinary hospital licensed to administer radiation therapy. Several complications of hyperthyroidism can be significant, includinghypertension(high blood pressure) and a heart disease called thyrotoxic cardiomyopathy. When the dose of radiation to the thyroid is very low, like might occur by accidental ingestion of litter box contents, then mutations leading to cancer can ensue. Usually, the TT4 level is so high that there is no question about the diagnosis (see the handout "Thyroid Hormone Testing in Cats"). Cats treated with radioactive iodine for their hyperthyroidism have several risks unrelated to the radioiodine therapy itself. Surgery will be performed if your cat successfully undergoes the initial treatment without complication. Radioactive Iodine Therapy Prior to the onset of symptoms he was eating a high quality dry cat food but when he started losing weight and begging for food we were told we could give him some baby food and wet cat food. Radioactive iodine therapy is a very effective way to treat hyperthyroidism (I-131). All rights reserved. For this reason, some cats with hyperthyroidism may require additional treatment to control secondary heart disease. In a study of 524 hyperthyroid cats treated with I-131, only 11/524 (2.1%) developed About TheCatSite.com. There are four treatment options for feline hyperthyroidism: medication, radioactive iodine therapy, surgery, and dietary therapy. Rarely, a permanent reduction in thyroid-hormone levels called hypothyroidism occurs after radioactive iodine treatment. Since you'll have to leave your cat at the facility for several days or more, it's not a question of dropping him off at a distant veterinary hospital and then picking him up the next day. Before treatment he was ravenous and losing weight -- typical of cats with that disorder I'm told. It is also common for hyperthyroid cats to exhibit increased vocalizing, particularly at night. The clinical significance of weight gain from the time of diagnosis of hyperthyroidism to 2 years after radioactive iodine therapy is unclear. Radioactive iodine. When it comes to survival, the studies that have been done show that cats cured of their thyroid disease by radioactive iodine live much longer (up to twice as long) when compared to hyperthyroid cats treated by methimazole. (a) Each licensee shall conduct operations so that -. Methimazole blocks excess thyroid hormone production rather than destroying the abnormal thyroid tissue, so the medication must be given for the rest of the cat's life. Hyperthyroidism may also cause vomiting, diarrhea, and hyperactivity. As to your question about "home-testing equipment" and "something else to monitor and determine (your) exposure," there really are no good options for that. An important take-away message about your newly-diagnosed hyperthyroid cat is that there is a wide range of treatment options, so you can likely find something that works for your family. What happens after my cat is released from the hospital? The food isnotmedicated. Toxicology and Applied Pharmacology, 2004. Our cat was treated for hyperthyroidism and has been back home for about two weeks. I might even suggest using disposable gloves when handling the litter box duties and when caring for the cat during the isolation time. 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. 7. Risks related to radioiodine: Side effects may include fluid retention, weight gain, elevated . Hence additional separation between the patient and children are unnecessary. If thyroid disease is a possibility, your veterinarian will likely order a blood chemistry panel and an analysis of thyroid hormone levels. In the hospital (or veterinary hospitals) we would use a Geiger counter with a thin-window probe to find the radioactive contamination. The inaccurate repair of DNA is rare, but can cause a cell to act wildly or grow into a cancer. If radioactive iodine therapy won't work for you and your cat, alternatives are available. Cats managed with diet or medication generally do well as long as their feeding is consistent, their medication is administered routinely, and follow-up blood and diagnostic tests are performed as scheduled. Feeding Hyperthyroid Cats Iodine restriction may help; weight loss is a . The following question was answered by an expert in the appropriate field: What testing equipment and protective clothing do you recommend for a nontechnical person who will be giving home care to an 18-year-old blind cat after he has spent four days recovering in the animal hospital from 131I treatment? Risks unrelated to radioiodine therapy: Your doctor will order a test called a radioactive iodine uptake and scan to determine the dose you will need. Protein and Carbohydrate Sources of Home-cooked Pet Diets, Deborah E. Linder, DVM, MS, DACVIM (Nutrition), Diet-associated dilated cardiomyopathy: The cause is not yet known but it hasnt gone away, Too hot? For example, some families cant medicate cats every day, so a more permanent solution such as radioactive iodine treatment or surgery may be best. Environmental risk factors have been investigated and may predispose some cats to hyperthyroidism, although the specific mechanisms are unknown. While the treatment is fairly expensive, over the long term it could be cheaper than medication and is on a par with surgical treatment. Clients owning hyperthyroid cats undergoing radioiodine therapy are always considered members of the general public. Malcolm Weir, DVM, MSc, MPH; Krista Williams, BSc, DVM; Robin Downing, DVM, CVPP, CCRP, DAAPM; Ernest Ward, DVM. Thyroidectomy (largely replaced by radioactive iodine . All three have risks and benefits. 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. The most common clinical signs of hyperthyroidism are weight loss, increased appetite, and increased thirst and urination. radioactive iodine All three treatments will reduce thyroid hormone levels and the signs of hyperthyroidism. But those instruments are quite expensive and are not readily available in stores. Radioactive iodine (RAI) is a treatment method for hyperthyroidism and thyroid cancer. In some cases, complications involving other organs may worsen this prognosis. This treatment involves administering an injection of iodine with a radioactive substance attached. Actually it is quite safe, because the radioactive iodine is absorbed only by thyroid cells; no other cells in the body are exposed to the radiation. This can be accomplished in several ways: Radioactive iodine therapy. However, an overactive thyroid is quite common. Number of cases per 100,000 persons exposed to a single dose of 0.1 Gy. Determination of Release Criteria for I-131 Therapy Cats in Conference Proceedings American College of Veterinary Radiology. Some hyperthyroid cats have thyroid cells in abnormal locations calledectopicthyroid tissue (thyroid tissue under the tongue, further down the neck, or all the way to the base of the heart), and they may remain hyperthyroid after surgery.
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