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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98 Comments

  1. I watched the consistency of the food while adding dripping but it was a lot more than I expected… I ran it at first dripping then with it streaming & I kept watching while I stirred the food but I didn’t measure how much water I added

  2. Ryan, here is a page I read and thought maybe it would help your Rascal. I hope it helps anyway.
    http://alexadry.hubpages.com/hub/What-to-do-if-your-cat-is-constipated

  3. This product is a paste that you can feed to your cat and it comes in tuna flavored. I read some of the reviews and most people were happy with giving this to their cats.
    Laxatone 4.25oz Tuna Flavored, you may be able to buy this from your pharmacy, or you can get it at Amazon.com for about 7 or 8 dollars I think.

  4. oh wait, that price was wrong….here it is again with the correct price.
    Laxatone 4.25oz Tuna Flavored
    by Mojetto
    4.1 out of 5 stars See all reviews (20 customer reviews) |
    List Price: $14.99
    Price: $12.99
    Sale: $4.90
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    7 new from $4.90 1 used from $4.99

  5. Dr. Michael Dym, VMD veterinarianAugust 14, 2012 at 6:47 pm

    I find that adding natural psyllium from health food store helpful to meals. 1/8 to 1/4 teaspoon per meal is all that is needed. Also a teaspoon of wheat bran or canned pumkpin to meals may also help.

  6. Dr. Michael Dym, VMD veterinarianAugust 14, 2012 at 6:51 pm

    Thanks for helpful link.

  7. Dr. Michael Dym, VMD veterinarianAugust 14, 2012 at 6:51 pm

    Laxatone can help in mild to moderate constipation. In moderate to severe cases, metamucil, psyllium and/or canned pumkpin and bran more useful.

  8. Dr. Michael Dym, VMD veterinarianAugust 14, 2012 at 6:52 pm

    Certainly reasonably priced.

  9. Yes, it is reasonably priced. I didn’t know that about pumpkin. I wonder if cats like pumpkin.

  10. Dr. Michael Dym, VMD veterinarianAugust 14, 2012 at 11:17 pm

    Many cats will eat canned pumpkin mixed in or with their food. OTher cats will put up their noses to it, as cats can certainly be finicky. The book I like with most useful at home suggestions for medical conditions, including constipation is the book The Natural Cat by Anitra Frazier, A must for all kitty lovers.

  11. Starky gives new meaning to the word finicky. I will have to try giving him pumpkin. I am going to get that book. Thanks for letting us know about it.

  12. Dr. Michael Dym, VMD veterinarianAugust 15, 2012 at 6:53 pm

    You are very welcome. Anitra’s book can be quite helpful. You can also consult with her direction at 212-663-0122 for a small fee for common cat health problems. I work with her often on cases when treating them holistically.

  13. Are you sure the Laxatone 4.25oz Tuna Flavored, is for constipation, it says it’s for hair balls? He has had trouble with them too & his hair is comming out since starting the medicine. The methimazole has completly stopped Rascal up. I’m so worried about him, and trips to the vet are so hard on him. He hasn’t taken 1 complete dump since starting it & that’s not enough all combined wouldn’t equal one time in the past. He’s shown me so much love & travel is so hard on him. Now he’s having a hard time jumping & is pulling himself up on the bed with his front paws. Please respond ASAP.

  14. That was what it said. It should have worked, but here is a better one. I looked up this drug and this one should help It is probably a better one, and I think Dr. Dym said something about this. Vetasyl
    VetasylBenefits:
    • A natural remedy for digestive issues
    • Helps reduce hairballs
    • Returns normalcy to your pets elimination
    • Convenient, and easy to administer
    • Contains 100% natural fiber sources
    • Formulated without preservatives, artificial flavors or colors
    • No reported side effects
    How it works:
    Vetasyl is sprinkled over food every day to aid in better digestion. The natural fiber source, which includes psyllium and barley, encourages natural elimination without the aid of chemicals.
    See this one is also for hairballs, so I guess that other one is for both. If you can’t get this right away, you should try pumpkin, that you can probably get sooner.

  15. I tried to post a link for this but I am having trouble posting it, I hope this works.

  16. Dr. Michael Dym, VMD veterinarianAugust 18, 2012 at 4:38 pm

    Laxatone can help both with hairballs and mild constipation. Vetasyl is another helpful product from 1800petmeds. If symptoms persist, may need enema and re evaluation by vet.

  17. Dr. Michael Dym, VMD veterinarianAugust 18, 2012 at 4:38 pm

    Thanks for the thorough information on vetasyl.

  18. Ryan, I know you don’t wanna do this, but you may have to give Rascal the suppository one time until the meds start working. Try the vetasyl if the Laxatone isn’t working. When I looked it up, it said it was for constipation. It’s probably for hair balls too. Starky was losing his fur in clumps, leaving it all over the house. Since he has been on the meth, he is doing better. Since his fur is so long and not so thick anymore, it’s a little easier to comb him, and thanks for the info on the bath. Luckily for me, the vet shaved those nasty fur balls near his rear. I still have to get a few more shaved off since he is so senstive when I try to comb him, but you’re right, the water does help. You really should give Rascal the supossitory at least once so he can poop. Then the medicine should be working and you won’t have to worry so much. I hope he is okay. I hope I don’t have any trouble posting this.

  19. oh I forgot to say, you are quite welcome DR. Dym. I wanted to make sure Ryan knew everything about it and other ppl will want to know this too.

  20. so let us know how you are doing Ryan.

  21. Thanks for all the info… I did get him going a little with a prescription forlactulose 10 gm/15 ml solution. I need something to maintain him with because the methazole is what stopped him up. The last 2 days he got 1 turd out each day. It sais to give it every 8 hours but we have done mostly once a day & twice on a couple of days.Now I want something safer & more natural & tasty for him. As it is now, I squirt 1 ml in his mouth with a needleless syringe & immediately give him his Friskeys wet food with methozole to get the taste out of his mouth. This seems to be helping a lot but is hard to do. He has been hungry several times a day & night so hopefully he’ll be back to normal weight soon. I’m glad to see him hungry & eating & going to the sandbox. He’s not completly back to normal yet but he’s got something comming out finanily. I have to deal with simmular symptoms so I know how he feels.The hair comming out didn’t start until he was on the methozole, he’s always had a ton of hair around the house but this is different. Clumps of hair all over & when I pet him it looks like my hand is a razor.. He’s a medium hair cat so there’s always a lot of fur & makes him look fat. He’s already jumping on the bed easier. I ordered the tuna flavored paste & that will be much easier to give him. He would’ve been in for an enema today had he not gone. Trips to the vet are so hard on him, especially in the heat so I try to take him as little as possible. He doesn’t like travel either & only time he’s not meowing in the car is when I’m holding him. I apreciate all the info & advice. He’s my very best friend & been through a lot together. If I’m in bed sick for days, he’s right next to or on top of me taking care of me. He even has gotten out of bed & followed me to the bathroom & sat with me while I was throwing up & gone right back to bed with me. Even my mother never did that even when I was very little. He means the world to me!!!

  22. Dr. Michael Dym, VMD veterinarianAugust 20, 2012 at 5:33 pm

    Sounds like you are very close. Also consider trying the supplement Vetri Hbr from vetriscience which can also help for hairballs, constipation, etc

  23. Good to know all is well with you Ryan. Glad u r ok.

  24. I ordered that book cuz they didn’t have it at the book store, so they are going to mail it to me. I can’t wait to get it. Thank you Dr. Dym.

  25. Well after we got Rascal’s thyroid in check we had his second blood test. We found out he has kidney Disease! This has brought many drastic changes to our lives. Having to give him iv fluids under his skin 2-3 times a week & with him hurting. Good luck to all & thanks for the info when he was diagnosed. He is my best friend who has loved me through so many years of pain. I’ll do my very best to protect him & help him. He has kept me fighting through my terminal illness & been the joy of my life. Ironically he is the only one who has put me first & shown me Unconditional Love! Hug your KITTIES!!

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