Hyperthyroidism in cats

Hyperthyroidism in cats is believed to be an autoimmune reaction.
The most common hormonal disorder seen in cats today is an overactive thyroid gland known as hyperthyroidism. While it was only recently characterized and identified as an illness in cats in 1979 at the Animal Medical Center in New York City, the incidence of this disorder has expanded tremendously over the past three decades. While it is most commonly a disease of cats over the age of ten, we are now identifying this disorder in younger and younger cats due to more accurate testing, including measurement of both a T4 and Free T4 thyroid levels.

The most common cause of this hormonal imbalance is due to a benign but functional tumor of the thyroid glands that leads to an overproduction of thyroid hormone. The debate in the veterinary community rests on what causes this benign tumor to develop.  The largest consensus rests on environmental factors, including potentially contaminant metals in certain screw top canned cat foods, to environmental toxins in carpets, as well as over vaccination where immunity to most viruses lasts for years to life of the pet.

As with most chronic disorders in our pets, it is believed to be an autoimmune reaction, where the immune system reacts against its own tissues leading to the development of this functioning tumor of the thyroid glands. Symptoms of this disease include increased thirst/urination and appetite with concomitant weight loss at the same time. Greasy or matted coats including excessive shedding can develop as well. Behavioral changes include easy overheating and panting, restlessness, vocalization, aggression and even changes in litter box habits resulting in feline house soiling. If left undiagnosed, high blood pressure, subsequent kidney and heart damage, and secondary disease of the heart muscle called cardiomyopathy can develop.

Treatment options include the prescription drugs Tapazole or generic Methimazole. 15 to 20% of cats may develop side effects on these drugs including lethargy, loss of appetite and vomiting. A lesser percentage can develop problems of the bone marrow, liver failure and even less common intense itching of the head and face. In roughly 20% of cats treated with Methimazole, elevation of kidney enzymes and possibly future renal failure can be seen. That’s why it’s so important for cats treated with medications for this condition to be adequately monitored through periodic exams, blood testing and blood pressure measurements. And while surgical removal of the thyroid glands used to be a popular treatment option, it has for the most part fallen out of vogue because of the close proximity of the parathyroid glands, as well as the surgical risk in many older cats.

The preferred method of treatment by many feline experts includes the injection of a single bolus of radioactive iodine, which selectively destroys only the functioning tumor of the thyroid glands. Most cats tolerate this treatment quite well, with the only downsides in my opinion being the initial expense of $1200 to $1500 dollars for the workup before the treatment, as well as the cat being isolated for at least a few days away from the guardian during the treatment period, in order to avoid radioactive exposure of the human guardian family.

As with all other hormonal diseases, I always recommend good vitamin supplementation,  including Soft Vitachews for Cats, Vetri-DMG, fatty acids such as Be Well Cat or Super Pure Omega 3, as well as liver support such as Denamarin or Denosyl, in order to protect the liver against the toxic effects of long term drug therapies.

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  1. Dr. Michael Dym, VMD veterinarianJuly 18, 2012 at 11:10 am

    Hi Sandra: You may want to try a more holistic or natural diet, ideally even a home made diet, if you can get your cat to eat it. They do so much better on a proper home made meat based diet. It may help to work with some feline nutritionists such as Anitra Frazier, author of the book The Natural Cat which can be find on line. Anitra can also be reached by phone consultation for nominal fee, as she consults with clients all over the world at 212-663-0122. Diet and appropriate supplements can indeed make a big difference in these cats.

  2. Not at all discusting… Well it is but we are pet lovers that will do anything for our pets… We would not have searched the net for answers about our cats conditions if we didn’t love them so much! Thanks for all the comments & updates on your progress!

    I have a suggestion get warm water in the tub & sit next to it with your cat, dip your hand in the water & pet your cat with the wet hand, rinse your hand & repeat, my cat hates baths too. Just make your cat think your petting him/her & soon they’ll be all wet & you’ll have a bathtub Full of hair & dirt. It’s what I resorted too. I use to give him a bath but I don’t want to fight him now that he’s over 16 years old. They had me mix his food with the medicine food and he ate. He hadn’t eaten much in almost a week & macked down. He use to throw up a bunch of water & since we started the medicine food and hasn’t since he’s been on it. Yesterday he threw up but food & I think because he grubbed so fast/much. I was glad when they let me mix the canned food I had, because Rascal is so picky that I have 4 cases of different flavors I had tried in single cans & know he likes. He would only eat his favorite & now doesn’t like it at all. I had to get him the cans with chunks of meat in it & now I have to buy him the pâté.

    Get your cat a blood test ASAP! It could be what we are going through with hyperthyroid or kidneys or liver… It could be something getting worse & a simple blood test will show all of these. Don’t wait because your & your cats lives could be much better.

    I found when mixing the foods that the medicine food is super dry for wet food & that could be why all our cats don’t like it. The manufacturer should read all our comments & might be able to adjust the moisture & flavor(s). My cat too is very picky!

  3. Dr. Michael Dym, VMD veterinarianJuly 18, 2012 at 11:22 pm

    Thanks for sharing our experiences with getting your cat to take meds and/or mixing foods.

  4. Thanks Ryan, I will have to try that. I’m just worried I might hurt him cuz he is sooo sensitive. I did however get most of the stickers out of him. A couple of days ago he went after a bird unbeknownst to me. I found a dove in the garage right next to our chair. It was so sad. I was helpless to do anything about it cuz it was obvious the dove had a broken wing. Starky hasn’t done that for a long time, and the birds usually are able to get away, plus with the cataracts in his eyes, I didn’t think he would be able to. The dove was almost the size of poor Starky since he is all skin and bones and fur now. Well anyway, I am going to go try what you suggested, and I will write more later. BTW a blood test is a necessity with this condition. I have to take him in every month to check his thyroid. I’ll be back later. God Bless you!

  5. I haven’t yet tried that, cuz I can’t even touch the knots without him thinking I am pulling his fur. I already got so many out, and that did take a while. I am contemplating trying just so he can feel a little cleaner cuz I don’t know at what point he stopped cleaning himself. He is still throwing up a little, but when I get his medicine, I think he will do better. Turns out the vet didn’t have any more either. I just have to see how it goes. My other cat Shadow is so jealous of him, she won’t even let him come into the bedroom at night. I had keep them apart, so I kept the door closed for a few nights but when Starky started howling, I could no longer do it. I felt so bad for starky. Now they just tolerate each other, but after Shadow made him bleed, I knew he was out for blood. I love them both, its so hard when they don’t get along. I have to keep Shadow indoors, and Starky wants to stay outside all day just to get away from Shadow.

  6. Dr. Michael Dym, VMD veterinarianJuly 21, 2012 at 11:29 pm

    Thanks for sharing all of your comments and feelings. Greatly appreciated.

  7. I took Starky for his follow up visit on Wednesday. Turns out he was anemic and dehydrated. Good thing I took him in. I had to leave him in the Hospital while they hydrated him and did more blood tests. I asked the DR if he could get those nasty knots out of him since I had to leave him there anyway. It ended up costing us $456.00 for the X-rays, blood work, office visit, hospital stay, and whatever else they charged us for. He is worth it though and I would do it again! I just wondered why they charge for the office visit and hospital stay, seems kinda like a double charge but at least he could tell just by looking at Starky, he needed to stay there. I called for the test results but he hasn’t called back yet. I picked him up later that day and called the next day for the results like he told us to. I have been just giving him the meds anyway since I can’t wait for him to call to let me know what is going on. He thot Starky had a tumor on his kidney, but thank God he doesn’t. That would be too scary as if I am not freaked out enuf by all this. I am going to call today and try again to get the results. Starky does look much better and seems a lot happier without those nasty knots and after his hospital visit. I hope everything is okay with all of you and your cats. Let me know how things are going with the meds and all Ryan and Angela and Elizabeth.

  8. I wonder how much it would have cost if Starky had to have a cat scan..lol instead of just xrays.

  9. Hi Sandra, Glad you took Starky in and I hope test results will be more helpful and not negative. Poor guy. Will keep fingers crossed for you. Elmo is hanging in there but I know he needs a Vet visit soon which I think I dread because he hates the experience and so do I and Yes the bills are always high but its just you don’t want more bad news. I think he might need to be tested for Diabetes. With the thyroid issues hoping that is not the case or tumors. I guess we have to accept that age catches up with all of us even our pets. Good luck and wishing Starky recovery!! Elmo has managed to fight it out. Sounds like Starky is a fighter too! Hugs!!

  10. Well the Dr finally called on Monday, and said to bring Starky in as soon as possible. We thot something was bad, so we took him in and he showed us the Xrays. He had thot when he checked him out he may have a tumor, but the Xrays didn’t really show one. He asked us if Starkys stools were hard and we said yeah, so he knows why he thot it was a tumor and told us he was sorry for the scare but he just wanted to be sure. Evidently it was the stools he felt, not a tumor. His thyroid levels were down to 70 so he first said to take him down to once a day on the methimazole instead of twice a day. We told him Starky didn’t have his medicine for a week, and I guess it had gone down more, then went back up due to the lack of meds. I told him he didn’t have any medicine, neither did 1800petmeds. Then we got the medicine from 1800petmeds so he was taking it again. Now Starky seems to be doing a lot better. They do have rapid results with the methimazole, and Starky didn’t have any side effects, so that was good. He only weighs 7lbs though so we have to fatten him up. He used to weigh almost 20lbs. Thanks Angela, and hugggs to Elmo. I hope everything is ok with him. Ryan & Elizabeth pls let me know how things are going with you. lots of love and huggs…xoxox.

  11. Wishing all of you and your pets good health and the very best. Our Sam Pepys is now in cat heaven and we all miss him, especially his puppy slaves. We’re sure that his spirit is there under his Bird of Paradise where he continues to survey the world. He moved in the pet door, bag and baggage when we were abroad and he was just a kitten. That was nearly 20 years ago. Whoever discarded him it was their loss and our gain. If another kitten suddenly appears I’m sure it will be Sam in his next reincarnation.

  12. Dr. Michael Dym, VMD veterinarianAugust 1, 2012 at 9:15 pm

    Thanks for sharing your sensitive thoughts and feelings.

  13. Thank you for the well wishes Elizabeth, I am so very sorry to hear that Sam is not with you anymore but now in Cat Heaven. It just brings tears to my eyes cuz I know exactly how you feel. We had another cat that came to our garage to hide bcuz somebody had abused it. He was so scard he wouldn’t come out, but my husband was able to coax him out and he became ours. He was not able to meow bcuz of the abuse, I don’t know what they did to him but we only had him for 9 years. It was 2 years ago, last March when he was laying next to me one morning in bed. I was petting him and he was purring. Suddenly he stopped purring, so I thot he had fallen asleep but then I noticed he wasn’t breathing and I totally lost it, I couldn’t stop crying. It was devastating. I know how you feel and I would give u lots of huggs if this were in person but I am sending you virtual hugggs instead. sandra{{{{{{{{{{{{{{{{{Elizabeth}}}}}}}}}}}}}}sandra

  14. Thanks for all the comments! I’ve learned a lot from all of your expierences. Rascal would never eat the food by itself, I did get him to eat it by adding more water than you’d expect, and mixing it with his food. His doctor said that if he wouldn’t eat the food by itself he’d have to go on the medicine. It did seem to be helping as he stopped drinking so much water that it would make him puke every day. Yesterday I has his doctor call in his prescription to my pharmacy & was able to pick it up when I went to get my medications. So now it’s waiting & watching to see how well he deals with any side effects from the pills. The cats use the same medication as we do, so if your ever out of it & can’t find it, have your vet call it in to your nearest pharmacy. I had to split the pills in half, but I already had a pill splitter! Thanks all for your stories! Sorry to those whom lost the battle but you know you will run across a kitten & it will be your kitties comming back to you! I remember when I got Rascal I had gone to a friends for dinner & as soon as I walked in I met the sweetest kitten. I picked him up & he loved on me & laid in my arm or lap the entire time I was there & I took him home. It was love at first sight but we seemed to have a Special bond. He loves to sleep as my cat from long ago who is no longer with us. I hope he doesn’t have to deal with many side effects and is on the road to recovery. My health is bad right now & it’d kill me to lose him! He’s only 16 so hopefully he has a long, happy, & pain free life ahead of him! If you can’t find the pills try your local pharmacy though so you don’t risk the numbers climbing back up!

  15. Dr. Michael Dym, VMD veterinarianAugust 2, 2012 at 9:55 pm

    THanks for sharing your kind thoughts.

  16. Thank you all for your good and positive thoughts. Our Sam will always be with us as are our other beloved pets who are waiting for us at The Rainbow Bridge. Life goes on and we appreciate the pets we have had and the ones who are still with us. We loved them all dearly and they had the best lives we could provide. They will always be with us in memory and bring smiles to our faces as we talk of them. We are glad we had them in our lives even though it is difficult when they have to leave. But that is part of life. Again thank all of you for your kind support.

  17. Thank you Ryan, but yeah I did a little research and found out I could get the meth at my pharmacy and then when I went in to pick up my meds I spoke to the pharmacist and she told me they would even compound it for me and flavor it with tuna. What’s even better….it’s only $29 for the same amount and you don’t have to pay extra for shipping, so that is going to work out great. I will have to get a 15 month supply which is fine. I tried to write on this blog yesterday after I read what Ryan wrote, but after I wrote a bunch of stuff, I accidently hit the wrong key, and it went back to the home page. I was unable to do it again bcuz my arm has been in so much pain my fingers didn’t want to do the typing. I couldn’t even type on the keyboard to my computer yesterday cuz I also have tendonitis and osteoarthritis in both arms, but it effects my right one more cuz of the pinched nerve. My Dr says I brought this on myself by not giving it a rest. I work tooo much in my garden and stuff…..well enuf about me…..I rambling again. I was going to tell you about B.C. the cat I was referring to that died next to me. He was such a special cat and when he died, Starky took a long time to get over it, he kept looking for him everywhere, and it was really hard cuz he could sense my emotions too. About 4 months after he died we were in Newberry Springs and they had these kittens and asked if we wanted one and I asked if they had a black kitten, and they did, we took that one. Actually I wanted them all, but we could really only get one more cat. Starky was not happy at all about it. We thot he would get over it but it just got worse and that night when Shadow made Starky bleed from scratching him we had to keep them separated for awhile. We had to keep our bedroom door closed. We kept Shadow in the bedroom cuz Starky likes to walk around to every room or he will meow relentlessly. We that for a few days but then when Starky started howling, I knew we had to keep the door open for him so he could come in our room too. He can’t jump on the bed cuz its too high. I felt so badly when I heard him howling, and I ran into the hallway to the front door where he was, and since he could barley see me cuz of the cataracts…..he started crying as soon as he sensed me. I felt so bad I just knew I had to keep the door open for Starky so he could come in our room even though he couldn’t jump on the bed. Well I wish you all the best, and I know you will find a new pet when the time is right even though you do have other cats, and Sams puppy slaves. Each one is so special. Every since B.C. died suddenly, I have been freaking out and having panic attacks for 2 years cuz I keep expecting to find Starky dead anytime, and even though I know he will die, I was just so freaked out about B.C.’s sudden death, it’s hard to deal with it.

  18. Thank you Dr. Dym and all of you good people who are struggling with hyperthyroidism in your cats. I appreciate the information from all of you and your kind support. I thank all of you and wish you and all of your pets long and healthy…and stress free lives. Take care and have a wonderful summer.

  19. Thank you Dr. Dym for making it possible for us to be able to share stories and questions about our cats with hyperthyroidism. You have been very helpful. Thanks everyone else for your comments and in put. This has been very helpful to me. sry for rambling about myself and my cat…didn’t mean to get carried away. Thank you Ryan for helping me with giving Starky a bath. I am going to try it today since I got my cat soap in the mail. Take care, I hope everyone is doing ok.

  20. Dr. Michael Dym, VMD veterinarianAugust 5, 2012 at 6:09 pm

    You are very welcome Sandra.

  21. No worries. As to Elizabeth Wilkinson’s cat Sam, I drove him to the vet and had him euthanized. Afterwards we gave him a beautiful service — flowers, candles, poetry readings, and toasted his life with a fine Bordeaux. Now Elizabeth keeps Sam’s ashes at her bedside and tells him about her day before she goes to sleep. Anyway, at 20 years old, he had stopped eating and drinking and looked like a skeleton. It was clear to me that he was preparing himself for death (cats are very spiritual creatures and really in touch with our Divine Creator); it was just like my grandmother, who told me at age 100 she didn’t want another birthday party because she “was done” and, sure enough, just before her 101st birthday she also stopped eating and drinking and just went to sleep a couple of days later, just like the cat!

  22. Dr. Michael Dym, VMD veterinarianAugust 8, 2012 at 11:20 pm

    Thanks for sharing your wonderful thoughts.

  23. When I mentioned about panic attacks in my last comment, I didn’t mean that I was having panic attacks every day for 2 years, I meant that is has been going on for 2 years, but it has only happened once or twice. Starky is doing better now. He is eating and not throwing up. He has gained almost 3 lbs. He seems a lot happier. He takes his medicine now without any problem because I mix it with a little tuna & he is happy to take it. I am not giving up on him, I know he will get better.

  24. Ryan, I was wondering, you said you mixed water with the y/d food? How much water did you add? Starky does not like it at all when I mix his food with water, nor does he like it when I mix 2 different foods together unless its tuna and chicken or salmon and tuna. He does not like the y/d can food at all. I supposed I should have tried mixing tuna with it, but I took all the cans I bought back to the store. I bought a whole case of it. He won’t eat the same food 2 days in a row either. to change the subject, I almost had a heart attack cuz I accidently got starky caught in the recliner. I did not know he had climbed under it, cuz Shadow was pestering him, and he was laying down at the time, then I tried to get up real quick and stop Shadow from pestering him, but Starky had already climbed underneath the recliner. I freaked out cuz I couldn’t get him out, but luckily it was just his tail when I finally got it out, he was fine, but I wasn’t…..lol….he is ok and I will be more than careful now….I can’t believe I did that. I don’t know how that happened. Well take care and let me know how u and your cat are doing, and Angela, u let me know how u and your cat are doing too. xoxoxo

  25. Does any of you know anything easy & gental I can use with my cat to help him poop? Since he started the pill he isn’t going & the vet only offered a suppository which my cat will not do. He scooted his ass away from a nurse when she was about to take his tempature so I know what a struggle that will be & I’m very worried about him… He’s very extremely picky so any ideas will be greatly apreciated.

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