My cat aged 20 as mentioned in a previous post has been treated with Felimazole for 6 months now for hyperthyroid.Her levels were the highest the vets have seen at over 150.She is doing great now and has normal appetite and her weight is back to normal and her blood pressure is now controlled well.She had some buckling of the retina before she stated on the BP treatment.
My question really is I know Felimazole has side effects can you tell me what they are and if they are life shortening or threatening and if they occur after a certain period of taking them.
To some extent I suppose it is academic as she is 20 years of age and couldn't undertake the surgery to remove the growth but it would be nice to know if there are any side effects to watch out for and if they could be serious.
She had her liver and kidney function tested and amazingly for her age she has normal values.

Hi, M<achair,

If you go to this web site you will find far more information thatn I can post here.
I hope this helps.

W

[www.noahcompendium.co.uk]

Thank you for that Walter it was very helpful.Just one question it said on no account should you crush the tablets. My husband is a brilliant one for giving them whole so is my daughter as she is a vet student but I must confess to resorting to crushing them up and adding them to food in desperation.Do you know why this is not recommended as if it is dangerous to the cat I will try and perfect my tablet giving technique-despite being 20 she is very strong!

Hi, Machair,

The risk is to the person who breaks up the tablet, especially if it is a woman of child-bearing age who may be pregnant.

W

hi ive just found this site and was wondering if you could give me some answers..My cat is 15yrs in august, she has been on felimizole for 2yrs, first i could only get her to take them in her fish x1 5mg a.m and p.m.
This worked for approx 12months then i was finding odd tabs she had spat out,so i decided i needed to be brave and give her tabs by mouth,igot her to take them really well,and after approx 1month she started itching,running and flicking constantly ,which resulted in her making her eye brows bleed.
Vet took more blood and results said she needed x3 5mg tabs daily, she was like a zomby!,but had stopped scratching herself.
Another blood test prooved it was too high of a dose and she has been put back on x2 5mg, she was finally looking great and eating, its been a week now and shes started the itching. running and flicking. its awful to watch.
I feel so helpless,shes due another blood test in 2 weeks.

Hi,
I cannot offer you any better advice than you are already getting from your vet, who is familiar with the case.
Talk to him about your concerns, and ask if there is an alternative or additional treatment available.
W

Hi Poppy. Ask your vet to prescribe the other thyroid medication available, by law they have to prescribe felimazole first but if there are side effects they can use the other. I think its called neomercazole.

I feel very nervous about starting my cat on felimazole. He is a stray that had sat in my garden for 2 years, always staring longingly into the house but looking so healthy and beautiful I assumed he must have a home.

Then one Summer I noticed he was itching his ears and face a lot till he bled. I started to put out water for him and then food each day. He wolfed everything and looked so grateful, but I still assumed he must have an owner.

He developed sores over, under and in one eye and then disappeared for about two weeks. He then reappeared with the bad eye removed and very neatly stitched. I took him to the local Blue Cross who phoned around all vets in the area and surrounds yet none had taken this cat in for treatment to remove the eye. The vet thought he was quite old, or had been a stray for a loong time as his remaining teeth were very bad. I had hoped they would find the address of his owner but it remains a mystery.

This grateful little cat has been with us now for some years. During that time he has had the remaining bad teeth removed.

A few weeks ago he developed symptoms of hyperthyroid. His T4 level was found to be 273. (I cant find anyone who has heard of a T4 level this high but the vet said it was not that high for a cat of his (presumed) age. I was given felimazole for him, but have held back after reading the possible side effects of this drug. Now I have just read that hyperthyroid cannot be cured by natural means and I am anxious about what I should do for him right away.

I feel like I have no choice but to put this gentle, loving creature on a chemical that will probably contribute to or hasten his death. He is still very active and plays with a ball and some string, but is too old for the operation or the iodine treatment.

I am wrestling with my conscience and wonder how others have coped with a similar situation with their cat.

I cant bear the thought of him being in pain. He's been so brave about all of his trials, no home or loss of his home, loss of an eye, no teeth and a slightly deformed hip, and still he is gentle and kind to our other cat who, through jealousy gies him a passing whck whenever he can.

Any thoughts would be so appreciated at this stage please.

Thank you. Ms J.

Hi,
Be advised by the Bluecross vet about using Felimazole. ALL medicines have side effects all of which have to be published, but in the very great majority of cases they are much less serious than the illness they are prescribed to treat. Which BX Hospital do you attend?
W

Hi Walter,
My cat is 18 and has been on felimazole for about 3 months and in that time his thyroid level has dropped only slightly (now on 130). My vet has increased his dose from 5mg twice a day to 7.5mg(5+2.5mg) once a day + also 5mg once a day. I started crushing the tablets and mixing them with cream cheese then spreading it on his coat so he had to lick it off - sounds a bit cruel but it was the only way i could get the tablets in him - (the normal way of administering them stopped him eating completely and he wouldn't come near me without growling, hence he lost .4kg of weight leaving him a scrawny size of 3.0kg!). Last week, my vet actually blamed me for crushing the tablets stating that's why his thyroid level hasn't dropped much, but with you saying earlier that it shouldn't be crushed only due to harming ourselves has made me feels slightly relieved and left me now thinking that maybe just not enough time has been allowed for his thyroid to drop in between blood tests??? (currently every 4 weeks). I know that the vet i have been seeing at the practice is newly qualified, in your opinion, would it be adequate to keep crushing the tablets as at the moment i'm lucky if i can get one a day down him.
Thank you,
Sylvia

Hi,

Felimazole tablets may be enteric-coated ( I am not sure), which protects the contents from being destroyed by the acids in the stomach, and allows them to go on to the intestine where the coating is dissolved and the active ingredient absorbed. If so, your vet is absoutely right.I do not think I said the ONLY reason for not crushing them was possible risk to you, but that is part of the reason for giving them whole.
Giving tablets to cats can be very traumatic for the cat and for its owner, and I can suggest no easy way.
W

My 13 year old cat is hyperthyroid but felimazole seems to be a problem. Initially he was on x2 2.5mg a day but this sent him hypothyroid and then he had a stroke so the dose was reduced to 1 tablet a day. His balance has never completely returned after his little stroke but had improved greatly. Recently he was tested and found to be hyperthyroid again so the dose was increased to half a tablet in the morning and one full one at night but after a couple of weeks of this his balance is going again and he's losing it at the slightest thing, for example yesterday he stretched at the side of our pond and toppled in and today he was washing his paw and he nearly fell over. What can we do? One isn't enough but one and a half seems to be affecting him badly. I don't want him to have another stroke as it may be alot more serious next time and he means the world to me.

Hi,
Modern medication, wonderful as it is, does not work in all patients all the time!

As is the case in humans, neurological problems do tend to recur in animals. In cats and dogs one has to balance the benefits of medication against the adverse side effects. In principle the lowest dose which keeps the symptoms under control is the right one.
Strokes, as we know them in humans, which are due to occlusion of or haemorrhage from blood vessels in the brain' are exceedingly rare in dogs and cats, and various other conditions which show the same signs do tend to be, wrongly, called 'strokes'. I suspect that this may be situation here.

W

Thank you for your reply, do you have any info on what else it might be if it's not a stroke please? He had another one yesterday even though we have reduced his felimazole to one a day. I took him straight to my vets and he's had a full blood panel which only showed the slightly hyperthyroid problem because of the low dose of meds, his ears hve been carefully examined, eyes checked for pupil dilation which was ok, a reflex test done on his legs which wasn't too bad and given a steroid jab like last time. Any info would be appreciated.
Thanks

Hi,

There is a condition in the dog known as vestibular syndrome. I am not aware of it occuring in cats, but the signs do mimic 'stroke' in humans.

W

Hello again, thanks for that info, I just looked it up and yes it seems it can occur in cats and be caused by (amongst other things) an under-active thyroid so this possibly explains why each time it happens it's after the vet thinks he needs more felimazole and he ends up hypothyroid. I'm slightly reassured by the fact the symptoms should resolve as long as he doesn't stray into being hypo again and I'm absolutely not risking upping his dose of tablets again, my vet agrees he is better being slightly hyper than hypo. He's already less wobbly but still very tired.

I can't thank you enough for your time and effort contributed towards animal care. Thank you!

My cat is 14 years old. Two weeks ago she had what I thought was a fit, shaking, salivering and urinating. I held her and after about three minutes she quietened down and slowly recovered. She had a second fit two days later. The vet did blood tests which showed she had a very high thyroid count which might be the cause and prescribed Felimazole 5mg twice a day. She had another fit again in the early hours of this morning. I awoke to hear what sounded like coughing or that she was about to be sick but she was having another fit. She took longer to recover and was panting/coughing on and and off for an hour or so afterwards. Could she possibly be having heart attacks? I had noticed during the day that she had been making sort of coughing noises.
Thanks for any help

Hi, Pollyanna,

I assume that the blood tests did not show any signs of singnificant kidney or liver failure, just hyperthyroidism?
The signs you describe are unlikely to be a 'heart attack', more likely to be the thyroid problem not yet being under control. It can take about three weeks for the Felimazole to take effect, and the dosage may need to be adjusted, on your vet's advice, before you see any real improvement.

W

Hi W !
Thank you very much for replying. In layman's terms the vet said my cat's sugar levels were OK and her kidneys were fine, the liver enzymes? were higher than normal, but not dangerously bad. The cat's eye reflexes were good. She is a very bad traveller and got into a panic state before we even arrived at the vets and her heart was beating very fast, and similarly her breathing. I was only given 10 day supply of Felimazole, but do not have to take my cat back for another blood test for a month. That is, she will have been without tablets for over two weeks before she is rechecked. Is this the normal procedure ?

Thanks again
Pollyanna

Hui,
You must be guided by your own vet who has first-hand knowledge of the case, but if you look up Felimizole on

www.noahcompendium.co.uk/Compendium/overview/search.asp?search=felimazole

you will see the information about using Felimazole.

W

Hi W

Many thanks for your help. I will have to keep my fingers crossed and hope for the best !

Regards
Pollyanna

Hi,

Here is a tip on getting a cat to take its medication.
If it is getting moist food, divide each meal into two portions - 1/3 and 2/3rds.
Mix the crushed tablet in the larger portion and put it into the food dish. Warm up the smaller portion and cover the food already in the dish. A cat will usually enjoy the warm and nice-smelling food on top, and then consume the rest without noticing the difference.

W

Hi - thanks for your prompt reply. So is it ok to crush the felimazole tablets then? It says on the packet not to but it seems like lots of people think it is ok. Possibly better than not taking anything at all?

thanks very much for your help!

Hi,

Absolutely!
When crushing the tablet be careful not to get it on to your hand. A good way of crushing a tablet is to put it into the bowl of a spoon, place another on top, and grind the two together.

W

Hi Walter,

My cat was recently diagnosed with Hyperthyroidism, and has been prescribed Felimazole 2 x 2.5mg daily. He's 13, and very independent, and comes & goes as he pleases. If for any reason he isn't in the house before I go to work (I work full time) for his tablet, would it be possible to give him both tablets in the evening when I get home, or do I just have to accept that he's missed that morning's dose? Obviously I want to do what's best for him, and don;t want him to suffer unnecessarily.

Thanks in advance,

Lisa

Hi,

I do not think it would be advisable to double up the dose to make up for a missed one, but you should really ask your vet this question.

W

My cat has only recently (2 months) been diagnosed with Hyperthyroidism. Our vet prescribed Felimazole 2.5mg, twice a day. His recent blood test has shown his levels are now in the normal range (18) - and I crush his tablets in his food, so it definately also works doing it this way. Also, my vet did specify that leaving your cat without tablets and then having tests would not show accurately if the tablets worked. However, he still isn't grooming properly and his coat has what I call a rivering effect (the coat divides) from the middle to back section - does anyone know why this is still happening? He also has now become a fussy eater.

Hi, Vicki,

The cat's coat can get very 'sticky' in these cases, which discourages self-grooming.
I think you will have to take a han in it and carry out regular grooming yourself.
You do not say how old your cat is, and if you have him insured, but the best treatment for younger cats - say less than 10 y.o. - is radiotherapy on the thyroid gland, which is now being carried out at a few veterinary centres in the UK. You could ask your vet if he thinks it might be appropriate in your case, and he may be able to refer you.

W

Hi, Vicki,

The cat's coat can get very 'sticky' in these cases, which discourages self-grooming.
I think you will have to take a hand in it and carry out regular grooming yourself.
You do not say how old your cat is, and if you have him insured, but the best treatment for younger cats - say less than 10 y.o. - is radiotherapy on the thyroid gland, which is now being carried out at a few veterinary centres in the UK. You could ask your vet if he thinks it might be appropriate in your case, and he may be able to refer you.

W

My Cat went on felimazole when he was about 13years old, subsequently had his thyriod removed at 15 and when it grew back five years ago went back on, he is still fine, despite being a bit stiff at his legs. We have his vitals checked about every 3 - 6 months to ensure his functions are ok, so far so good, heart, liver & kidney functions okay and no diabetes.

Good luck