Hyperthyroid cat - minimal impact of vidalta

RE: Hyperthyroid cat - minimal impact of vidalta

Kate Richardson — Sat, 11 Jul 2015 21:47:43 GMT

Also consider increased git motility due the hyperthyroidism so increased guy transit time and reducing time for absorption so try dosing bid and also consider concurrent git pathology causing reduced absorption.

RE: Hyperthyroid cat - minimal impact of vidalta

Stephen Courtney — Sat, 11 Jul 2015 08:41:34 GMT

Agree with what everyone has said - cats that fail to respond to suitable doses of meds may well have non compliant owners - but then ask yourself why they are paying for repeat blood tests? I suspect many of them have carcinomas rather than adenomas. fortunately i don't often get cats that do this. i've just PTSd my most frustrating case ever - the vidalta tech support people said the maximum dose was 25mg however, with an option to go off label to 30mg.

At 25mg this cat had a normal heart rate but otherwise was screamingly hyperthyroid. Owner had finally had enough yesterday, fair enough. At first I had thought she was fibbing about the pills, but her purchase record matched what she said she was using ( liars always get this one wrong in my experience, or start talking about pills their friend who's cat died - often with the implication it was one of my failures...- gave them!)

On the whole though i prefer felimazole as the control can be more finely tuned and the pills can be crushed into food ( off label advice of course but come on!) for the unpillable kitties.

I get more adverse reactions with vidalta, usually vomiting and anorexia, because i think a lot of people still crush the tablet, or hide it in food and it gets chewed - so the cat absorbs 24hr worth of meds all at one.

Of all the tablets i ever prescribed for this i preferred neomercazole by far.

RE: Hyperthyroid cat - minimal impact of vidalta

grumpyoldman — Sat, 11 Jul 2015 00:50:04 GMT

[quote user="Martin Atkinson"]a partial thyroidectomy is a standard procedure in humans with Grave's disease, that don't do more in our patients.[/quote]

The endocrinology guru from New York presented his scintigraphy findings at Cambridge last year and there are often 5-7 focal centres of radioisotope uptake between the main glands and the mediastinum. Radioactive therapy is a none starter for our clients start talking more than 250-300 on the old knackered cat and they are quickly worrying about their fortnight in Majorca well its really old anyway and it was not really theirs after all they rescued it as a stray lalalalal !!!,they are also

less than 100% compliant with meds . I often take 1 or 1.5 its a lot easier with a loupe ,no parathyroid issues for over 10 years . And if you judge it right no hypothyroidism either ,many will stabilise between 30 and 40 . So your not taking the manhole cover off an underlying renal disaster. Sooner or later they go high again and need meds but its more manageable with fewer swings . The exceptions are the ones with mediastinal nasties . One of those pops up about every 4-5 years.

RE: Hyperthyroid cat - minimal impact of vidalta

Martin Atkinson — Fri, 10 Jul 2015 19:03:58 GMT

[quote user="grumpyoldman"]you can go 50/50 with some of these cats , a unilateral thyroidectomy [/quote]I often wonder why, when a partial thyroidectomy is a standard procedure in humans with Grave's disease, that don't do more in our patients.

RE: Hyperthyroid cat - minimal impact of vidalta

grumpyoldman — Fri, 10 Jul 2015 18:59:24 GMT

you can go 50/50 with some of these cats , a unilateral thyroidectomy then suppress if its still a bit high , no one wants to create an azotaemic hypothyroid ,because all the client will remember is that it was eating well before you started .

RE: Hyperthyroid cat - minimal impact of vidalta

Matt Hilary — Fri, 10 Jul 2015 17:29:57 GMT

Thanks for your help - much appreciated.

RE: Hyperthyroid cat - minimal impact of vidalta

Andrew Kent — Fri, 10 Jul 2015 14:26:18 GMT

[quote user="Robin Grimmer"]The maximum recommended dose of Vidalta is 20mg sid[/quote]

I know that is what the data sheet says but I think that was because in the licensing work there was little experience above this dose. Last time I spoke to MSD about it they were reasonably happy with doses up to 40mg, albeit with a slightly increased frequency of monitoring.

The other thing to remember with Vidalta is that the absorption is significantly altered by food (40% greater with food) and so it is important to be consistent from this respect.

Andy

RE: Hyperthyroid cat - minimal impact of vidalta

Robin Grimmer — Fri, 10 Jul 2015 13:55:18 GMT

I wouldn't necessarily say it's lack of compliance. The cat is showing some response. Some cats with very high T4s don't do very well medically. The maximum recommended dose of Vidalta is 20mg sid. You can increase but there is much more risk of side effects. Felimazole gives you more dose options. If the renal function is ok this cat might be a suitable candidate for I131 or surgery.

RE: Hyperthyroid cat - minimal impact of vidalta

Andrew Kent — Fri, 10 Jul 2015 13:49:52 GMT

Hi Matt,

Everyone has their own preferred medication of hyperthyroidism, mine is Vidalta so I would continue with it, I have had a few similar cases where we didn't start to achieve control until we got to higher doses, but sometimes they suddenly respond as the dose is upped so I would keep doing what you are doing. I don't see any reason to think that felimazole would be more effective at this stage.

A few of the cats I have seen with this kind of response have turned out to have thyroid carcinomas rather than benign disease so may be worth warning the owner of that.

Andy

RE: Hyperthyroid cat - minimal impact of vidalta

Martin Atkinson — Fri, 10 Jul 2015 13:26:08 GMT

This shouts of lack of compliance, owners never cease to amaze me the number of ways they can find to fail to comply but insist they are doing so. Maybe you should get them to demonstrate their method of administration in front of you, but I would use Felimazole as my first line treatment anyway.

However, I had a cat with a similar TT4 level yet it was asymptomatic to start with and was only picked up on a routine pre-dental examination/profile. O couldn't give tablets, didn't want surgery as it was bilateral and last cat she had which had a bilateral thyroidectomy went hypocalcaemic so we tried methimazole gel. She couldn't find enough bare skin to put enough of the stuff on and it still had a TT4 of >200. It finally went for I131 therapy and is now hypothyroid and azotaemic and on Leventa. C'est la vie.