# Kitty Just Started Methimazole



## Jed (Nov 8, 2008)

Our 14 year old female came down with jaundice due to a liver problem, and this was helped greatly with Denamarin. At the same time, her weight dropped dramatically while her appetite and thirst went up. Sure, enough...hyperthyroid. She started on Methimazole today. Does anyone know how soon we'll start seeing an improvement? She's doing well in other respects... purrs, follows the sun, grooms... but we'd like to see her put weight back on. Thanks everyone.


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## Heidi n Q (Nov 22, 2006)

I replied because it has been almost 7hrs since you posted. Unfortunately, I have no experience/advice to share with you, other than I helped save my cat from jaundice in 2006 around this time of year. Most of the regular members were expecting this forum to be down over the weekend, so many of them are probably not checking in. My reply will bump this to the top and hopefully someone with experience in this matter will chime in.

Welcome to CatForum and best of luck to your kitty,
Heidi


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## Jed (Nov 8, 2008)

Thanks, Heidi, for your help and the nice welcome.
Jed


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## laurief (Jun 22, 2008)

Jed, please be aware that many, many vets start cats on waaaaay too high a dose of methimazole, and that can cause very severe and serious side effects, generally 2-3 weeks after beginning the drug (though adverse side effects like vomiting and inappetance can occur sooner than that). High dosing is very old school medicine, but unfortunately far too many vets haven't caught up with current dosing recommendations. The safe way to administer methimazole adheres to the adage, "start low and go slow", meaning to start at a low dose and slowly increase dosage should the need arise.

So, may I ask at what dose your vet has started your cat? If it's more than 1.25 mg twice daily, you should be doing your own research to decide if you are comfortable with the higher dose. Many folks start their cats at just 1.25 mg once a day.

I wish I'd known about current dosing recommendations before I started my cat, Billy, on methimazole. My vet started him on 2.5 mg twice daily. Within 3 weeks, Billy was so hypOthyroid that his T4 didn't even register on the lab equipment. It took about 7 months to get him regulated on a correct dose. Regardless of your cat's starting dose, be sure to have his T4 tested again no more than 3 weeks after beginning the med so that his dose can be adjusted, if necessary.

I strongly recommend you join the Feline-hyperT mailing list. Those folks REALLY know this disease and all of the ins and outs of the various treatment options. If you join the list and spend some time reading the current and archived messages, you'll learn a ton. And of course you can post any questions you may have to the list, as well. Here's a link to the list:

http://pets.groups.yahoo.com/group/feline-hyperT/

I wish you and your cat all the best.

Laurie


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## Jed (Nov 8, 2008)

Laurie, it's 5mg twice a day!


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## laurief (Jun 22, 2008)

That is way, WAY too high a starting dose, esp. for a cat who has had liver problems! Please, PLEASE reduce that dose to 1.25 mg (1/4 tablet) once or twice a day before your cat suffers serious and potentially devastating side effects. Tell your vet that after doing some research, you are extremely uncomfortable with that dose and have made the decision to reduce it substantially. Then make sure you go back in 3 weeks to repeat the T4 test so that you can slowly increase the dose, if necessary.

I'm begging you, do NOT continue at 5 mg twice daily.

Laurie


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## Jeanie (Jun 18, 2003)

It sounds to me as if Laurie has some experience with this problem. However, we can not prescribe for your cat. Considering what Laurie has posted, I would do a lot of reading today, so that you can discuss the possibility of a dosage change tomorrow knowledgably. I so hope your cat's health can be restored, and that you have many more years with her.


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## laurief (Jun 22, 2008)

Absolutely do as much research and reading on hyperT and its various treatments and treatment side effects as possible, and absolutely discuss lowering the dose of methimazole with your vet. If your vet is reluctant to reduce the dosage for any reason, I strongly urge you to immediately seek a second opinion from a vet in a different clinic.

Also, as I mentioned earlier in this thread, join the hyperT mailing list. As a member, you will not only have access to the message archives and be able to post questions directly to the list, but you can also access the files section of the list website which contains extensive information on many aspects of hyperT.

I wish you all the best with your cat.

Laurie


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## kyparamedic (Mar 30, 2008)

I don't remember the dose my cat started on but he showed improvement pretty quickly. He was on the methimazole for 6-8 months before I decided to go with the radioactive iodine treatment. I went with that for 2 reasons. One, the methimazole was a pain to administer. He's very finicky about treats and his food so getting the pill down him twice a day was a challenge. They make a transdermal gel for the ear but he got to the point that he'd run when he saw me with the syringe. I also wasn't confident that he was getting a consistent dose. The 2nd reason is that the life expectancy is longer with the iodine treatment and it's safer. It's been 14 months since the treatment and he's doing good. He's actually gained back 8 lbs. and I'm trying to get him to lose weight. I encourage you to read up on hyperthyroidism. After the treatment my cat's kidney levels crept up but have since normalized for the most part. Hyperthyroidism can mask kidney failure and it can be a balancing act.


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## Jed (Nov 8, 2008)

I called another vet who I've known for many years. He said that the range is 2.5 to 5 (twice a day), and depends on the data from the blood work, which I didn't have. According to the manufacturer, 5(x2) is the recommended dose. On the other hand, I found an article on-line from a vet journal that recommended starting low and gradually increasing! My wife discussed this with the vet, and the vet indicated that the dose was based on the blood test. She (the vet) wants to continue this dose for a 10 day course and see how the next test looks. 

Kitty is still eating and drinking, but she isn't as ravenous for food and water as before. The potential serious side-effect of facial itching hasn't happened. She's lethargic, but she was slowing down even before this, so while that's a known side-effect, I can't say it's related. 

Laurie, I appreciate your passion, but taking this all together, I'm going to stay with that dosage BUT continue to monitor her closely.


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## laurief (Jun 22, 2008)

Jed,

In a hyperthyroid state, your cat's thyroid has flooded her system with excess thyroid hormones. Methimazole acts to slow (or stop, if the dose is too high) the production of thyroid hormones, but it has no action on the excess hormones that are already circulating through her system. That's why you may not see the effects of a methimazole overdose for a couple of weeks until the circulating hormones dissipate from her system. When those circulating hormones are gone, your cat may experience severe vomiting, inappetance, lethargy, and various other symptoms.

If those symptoms appear or your cat becomes severely hypothyroid, your vet may recommend ceasing methimazole altogether for a while. Rapid cessation of methimazole, however, can cause a whole other set of serious side effects, among which may be thyroid storm, a very serious and potentially fatal complication if not properly diagnosed and effectively treated.

Just please be aware of the potential effects of this sort of dosing so that you can contact your vet immediately if your cat's condition deteriorates.

I sincerely hope that all goes well.

Laurie


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## Jed (Nov 8, 2008)

I'm sorry to report that Velvet slowly deteriorated. We stopped the Methimazole, but it didn't make any difference. Besides her thyroid problem, her liver was not functioning properly. She suddenly refused to eat or drink, and became even more listless. After two days, we had to end her misery. She was 16 years old (I gave the wrong age originally), and slept on my wife's arm almost every night.


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## marie73 (Jul 12, 2006)

I'm so very sorry for your loss. She was obviously loved very much and that love was surely returned to you and your wife every day.


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## Heidi n Q (Nov 22, 2006)

I'm very sorry that Velvet passed. 16yrs is a fabulous age for a cat to have been cared for and loved by her family. She was a very lucky cat to have you and your wife.
Please accept my condolences.
Heidi


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## beth1954 (May 19, 2004)

I'm so sorry about Velvet. Like the others have said, she was a very lucky cat to live that long with people who loved her. We have lost 3 cats to hyperthyroid. It's not always easy to treat. Some cats do really well, others don't. But I know Velvet had a wonderful life! You'll be left with so many memories. Not a week goes by that we don't at some point talk about Tigger (who was 17 when he passed,) Habibi (was 14 when he passed,) or G.G.--we don't know how old G.G. was--he was a stray and we don't have any idea of his age.

Do something nice for yourself today. Velvet would want you to.


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## Jed (Nov 8, 2008)

Thanks, everyone, for your kind thoughts.


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