Vestibular syndrome

RE: Vestibular syndrome

Anthony Dennison — Thu, 05 Jan 2017 15:11:24 GMT

[quote user="Anthony Todd"]I know I'm repeating myself but show me just some evidence of thyroxine causing harm in therapeutic doses, even in euthyroid animals.[/quote]

My nurses dog was slightly hypothyroid (amongst other issues), I started on a low dose of thyforon and the dog started showign signs of hyperthyroidism within a week. As soon as we stopped the meds the dog was normal again.

RE: Vestibular syndrome

Martin Atkinson — Wed, 04 Jan 2017 13:17:18 GMT

[quote user="Anthony Todd"]It is now obvious, even to me, that a trial dose of thyroxin, can't be supported but also that a low thyroid level, in sick animals can be expected and the citations actually say testing for thyroid function is unnecessary.[/quote]Hallelujah.

The opposite really but to add to this I'm treating a proven hyperthyroid cat for pyothorax and it has euthyroid sick syndrome. At the moment it could do with every bit of appetite stimulation it can get so we've stopped therapy for its hyperthyroidism but if it recovers then we will monitor T4 levels and start to treat it again when they reach high normal (over 45 nmol/l).

RE: Vestibular syndrome

Lucy Fleming — Wed, 04 Jan 2017 10:29:11 GMT

[quote user="Lucy Fleming"]wouldn't start a dog on thyroxine supplementation on low T4 measurement alone as it is too variable and can be lowered by concurrent disease (potentially the vestibular disease itself, I suppose). TSH measurement is required to differentiate these 'euthyroid sick' cases and a truly hypothyroid case - in the latter the TSH is elevated as the brain desperately tries to instruct the thyroid to make more T4, which it is incapable of doing. In a normal dog with low T4 due to illness the TSH will not be increased[/quote]

I'm slightly hurt that you had to google that when I thought I had summarised it so well! Clearly it was a case of TL: DR

RE: Vestibular syndrome

Gillian Mostyn — Wed, 04 Jan 2017 07:43:42 GMT

RE: Vestibular syndrome

Anthony Todd — Wed, 04 Jan 2017 07:28:31 GMT

[quote user="Noweia"]may be harmful [2][/quote]

It does, but is sometimes the case, when I go to [2] there is no actual evidence that it is "harmful", just a recommendation not to supplement thyroxin because it has no benefit, particularly in humans on cardiac bypass [!?], and a reverse reference back to the original paper......!

Please correct me if I have misquoted or misunderstood but, as has been shown before, linked references, when the link is looked at, do not always support the thesis they appear to.

It is now obvious, even to me, that a trial dose of thyroxin, can't be supported but also that a low thyroid level, in sick animals can be expected and the citations actually say testing for thyroid function is unnecessary.

RE: Vestibular syndrome

Noweia — Tue, 03 Jan 2017 19:46:31 GMT

[quote user="Anthony Todd"]PS still waiting for evidence of this terrible toxicity of thyroxin.[/quote]

See my post above.

[quote user="Anthony Todd"]

Lots of references to this so, after 5 pages, of insults and abuse I feel it's been worthwhile.....

http://cursoenarm.net/UPTODATE/contents/mobipreview.htm?37/50/38703/abstract/2

This seems a comprehensive review in humans.[/quote]

And in that link you posted, it says:

[quote]Despite these abnormalities (the low T4, T3 and TSH of sick euthyroid or transient central hypothyroidism), treatment of these patients with thyroid hormone, while controversial, appears to be of little benefit, and may be harmful [2][/quote]

RE: Vestibular syndrome

Anthony Todd — Tue, 03 Jan 2017 19:14:19 GMT

[quote user="Thomas Johnson"]Unwell older dogs often have a low T4, it's called sick euthyroid syndrome, they're not hypothyroid as the T4 will often return to normal if they recover from their illness.[/quote]

Lots of references to this so, after 5 pages, of insults and abuse I feel it's been worthwhile.....

http://cursoenarm.net/UPTODATE/contents/mobipreview.htm?37/50/38703/abstract/2

This seems a comprehensive review in humans.

RE: Vestibular syndrome

Gillian Mostyn — Tue, 03 Jan 2017 18:59:46 GMT

[quote user="Anthony Todd"]PS still waiting for evidence of this terrible toxicity of thyroxin.[/quote]

As with most drugs, a single or short course is very unlikely to do any harm. Generally speaking, commonly used drugs have high LD50s. Thus, as you speculate, a few doses of thyroxine are unlikely to do any harm in the majority of animals.

Or do any good, if the dog is euthyroid.

These days, our drug choices are usually based on clinical evidence of benefit, rather than simply unlikely to do harm.

RE: Vestibular syndrome

Thomas Johnson — Tue, 03 Jan 2017 18:50:17 GMT

[quote user="Anthony Todd"]So how do you explain the low T4, or is this just because the wrong parameter was measured, or totally irrelevant, or what?[/quote]

Unwell older dogs often have a low T4, it's called sick euthyroid syndrome, they're not hypothyroid as the T4 will often return to normal if they recover from their illness.

RE: Vestibular syndrome

Martin Atkinson — Tue, 03 Jan 2017 18:35:21 GMT

[quote user="Anthony Todd"][I'm thick remember][/quote]No you've just got a thick skull!

RE: Vestibular syndrome

Anthony Todd — Tue, 03 Jan 2017 18:24:50 GMT

[quote user="Thomas Johnson"] I am happy that it is most likely to be idiopathic peripheral vestibular syndrome I often give Cerenia as it's likely that they are nauseous, and I have very occasionally given diazepam if they're very distressed.[/quote]

So how do you explain the low T4, or is this just because the wrong parameter was measured, or totally irrelevant, or what?

Which was where we started.

PS still waiting for evidence of this terrible toxicity of thyroxin.

RE: Vestibular syndrome

Thomas Johnson — Tue, 03 Jan 2017 18:16:26 GMT

[quote user="Anthony Todd"]I should have said, "instead of the usual "placebo" of steroids etc for vestibular disease it might be better, and more logical, to give a short course of thyroxin and see if that fixed it which it probably would"[/quote]

The trouble is that the majority of the dogs which present with vestibular signs are suffering from idiopathic peripheral vestibular syndrome and will get better on their own in less than a week with no treatment, so any treatment you give can appear to have a remarkably good success rate. If after taking a history and a thorough clinical examination I am happy that it is most likely to be idiopathic peripheral vestibular syndrome I often give Cerenia as it's likely that they are nauseous, and I have very occasionally given diazepam if they're very distressed.

RE: Vestibular syndrome

Anthony Todd — Tue, 03 Jan 2017 18:06:22 GMT

[quote user="Lucy Fleming"] Fine, for a short-term treatment, as the animal gets better, and you stop the treatment.[/quote]

Finally [I'm thick remember] I get why posters are getting irate, and some even insulting.[tears fell]

I should have said, "instead of the usual "placebo" of steroids etc for vestibular disease it might be better, and more logical, to give a short course of thyroxin and see if that fixed it which it probably would"

RE: Vestibular syndrome

Anthony Todd — Tue, 03 Jan 2017 17:22:19 GMT

[quote user="Martin Atkinson"]There is absolutely no logic in giving it thyroxine without testing first and plenty that says you shouldn't [/quote]

And some have said they give the dreaded steroids....so why not give something which some say may help...

We all do it all the time when we know what is wrong and what will fix it, or do you always take a blood before treating a cat bite?

RE: Vestibular syndrome

Martin Atkinson — Tue, 03 Jan 2017 16:44:15 GMT

[quote user="Anthony Todd"]Just give me some evidence of thyroxin toxicity and I'll accept it, but I just don't accept it because everyone says it....[/quote]Anthony, when will you get it through your thick skull that the argument is not about whether a single dose of thyroxine causes a problem or not but that you are now suggesting that every dog with vestibular disease should have a course as part of its treatment for that condition on the basis of a spurious piece of research which you have only just heard about third hand when neither you or I have ever diagnosed a case of hypothyroidism as the cause of vestibular disease in our lives. There is absolutely no logic in giving it thyroxine without testing first and plenty that says you shouldn't - there are already posts on here about dogs given thyroxine whcih caused side effects when then were misdiagnosed purely on a low T4.

RE: Vestibular syndrome

Lucy Fleming — Tue, 03 Jan 2017 16:30:04 GMT

[quote user="Anthony Todd"]It may well be that the vestibular disease produces the low blood values [/quote]

This is why I wouldn't start a dog on thyroxine supplementation on low T4 measurement alone as it is too variable and can be lowered by concurrent disease (potentially the vestibular disease itself, I suppose). TSH measurement is required to differentiate these 'euthyroid sick' cases and a truly hypothyroid case - in the latter the TSH is elevated as the brain desperately tries to instruct the thyroid to make more T4, which it is incapable of doing. In a normal dog with low T4 due to illness the TSH will not be increased. You still get the odd case that doesn't read the book, but combining the tests makes the diagnosis much less equivocal.

[quote user="Anthony Todd"]This is a dog that was apparently not hypothyroid until the test, subsequent to the development of vestibular disease only[/quote]

Yup, and I must admit I'm not sure I have been sufficiently convinced to T4/TSH test every vestibular dog I see, though I might be more likely to remember to consider it. Signs of hypothyroidism such as weight gain, coat changes etc can be subtle and non-specific - I don't test every fat middle aged labrador either, but neither would I trial them on thyroxine to see if they get slimmed. In fact in those cases, I'm more likely to test the thyroid to convince the owner that no, they are not hypothyroid and no, there is no medical reason they are not losing weight, it is entirely dietary!

Mind you, if you believe Jean Dodds we are all underdiagnosing hypothyroidism so perhaps she would agree with your approach. According to her it can only be effectively diagnosed via her lab.

RE: Vestibular syndrome

Anthony Todd — Tue, 03 Jan 2017 16:19:56 GMT

[quote user="Martin Atkinson"]Anthony Todd is as exasperating and intransigently dinovet as ever?[/quote]

Just give me some evidence of thyroxin toxicity and I'll accept it, but I just don't accept it because everyone says it....

and modvets are the ones preaching EBVM.....

RE: Vestibular syndrome

Anthony Todd — Tue, 03 Jan 2017 16:16:26 GMT

[quote user="Lucy Fleming"] But if you are using that improvement to decide to continue treating with thyroxine (as presumably you would, after a successful treatment trial) then the animal is on a medication that they may not need, for the rest of their life.[/quote]

But if you do the blood and find the dog is therefore hypothyroid it will be on medication for ever and almost certainly more bloods as well, even though the vestibular disease has gone and there are no other signs of hypothyroidism......!!!

This is a dog that was apparently not hypothyroid until the test, subsequent to the development of vestibular disease only, but will now be on thyroxine for ever, so same same.

It may well be that the vestibular disease produces the low blood values and these may bounce back when the vestibular disease disappears,particularly as these patients have no other signs or symptoms of hypothyroidism, as far as has been observed so far.

Pleased that the myth of "thyroid toxicity" in even high therapeutic doses, appears to be unsubstantiated even if it is hard to extract the rather luke-warm admission.

RE: Vestibular syndrome

Martin Atkinson — Tue, 03 Jan 2017 14:14:28 GMT

I've just claimed this thread for the first 30 minutes of CPD for 2017. In the section which asks what I have learned can I write: Anthony Todd is as exasperating and intransigently dinovet as ever?

RE: Vestibular syndrome

Noweia — Tue, 03 Jan 2017 14:02:50 GMT

N=2 or 3 but we've had a couple of dogs that were diagnosed hypotyroid based on T4 alone, the dogs were very agitated, had tachycardia and panted excessively on even the low doses. We now check TSH too!

RE: Vestibular syndrome

Gillian Mostyn — Tue, 03 Jan 2017 12:33:16 GMT

Sorry- a bit of a tangent, but dying to share this amazing info:

Someone told me that if I sprinkle a teaspoon of salt on my driveway every day, it keeps lions away. It must work, because I've never seen a lion. It's worth a try - and, afterall, it can't do any harm, can it?

RE: Vestibular syndrome

Lucy Fleming — Tue, 03 Jan 2017 11:17:45 GMT

I would tend to agree with you that the potential for 'harm' is unlikely apart from a few cases (eg uncontrolled addisons), but my concern with using a treatment trial in this situation is that we are expecting the condition to (most likely) resolve by itself anyway. Therefore any improvement might be due to the treatment, or might be due to the natural course of the disease/ healing process. Fine, for a short-term treatment, as the animal gets better, and you stop the treatment. But if you are using that improvement to decide to continue treating with thyroxine (as presumably you would, after a successful treatment trial) then the animal is on a medication that they may not need, for the rest of their life. This represents an unneccessary expense for the owner (much greater, over time, than the cost of the blood test) and chronic over-supplementation could also lead to clinical signs.

There are situations where a treatment trial might be as useful as a blood test/ biopsy etc but IMO hypothyroidism is not one of them, clinical signs are too insidious and non-specific.

RE: Vestibular syndrome

Anthony Todd — Tue, 03 Jan 2017 09:53:32 GMT

[quote user="Martin Atkinson"]potential for harm[/quote]

Sorry for the turbo post but please give me any evidence for this at all apart from single, massive overdose, and even then the "harm" is short lived.

RE: Vestibular syndrome

Martin Atkinson — Tue, 03 Jan 2017 09:37:59 GMT

[quote user="Kate Richardson"]

And on another side Anthony Todd you are very critical of people doing what you deem 'unnecessary tests' yet you are quite happy to advocate 'unnecessary treatment'. Care to explain your logic?

[/quote]What surprises me is not that he is advocating giving treatment with little rational basis and the potential for harm but that it is something other than corticosteroids!

RE: Vestibular syndrome

Nicola Cole — Sun, 01 Jan 2017 20:52:46 GMT

[quote user="Anthony Todd"]

CONCLUSIONS AND CLINICAL IMPORTANCE:

Although the pathogenesis in dogs without evidence of infarction is unknown, central vestibular dysfunction appears to be a rare but reversible neurologic sequelae of hypothyroidism.

from:

J Vet Intern Med. 2006 Nov-Dec;20(6):1363-9.

Hypothyroid-associated central vestibular disease in 10 dogs: 1999-2005.

Higgins MA1, Rossmeisl JH Jr, Panciera DL

And there's other citations too....

So it's worth doing a trial dosage, 'cos it'll probably work....

Retires gracefully.

[/quote]

My problem with using a paper such as this is the very small number of patients involved, and within this their differing findings ie some infarcts, some not...further reduces the number of patients involved that then fit a set with very few other variables.....

Looking further the numbers involved with some of the papers looking at peripheral vestibular syndrome and its link-sites 26 animals involved over a number of years. Looking at how common peripheral vestibular syndrome is, and how common hypothyroidism is you would think there would be significantly more patients involved in these papers.

Now, that doesn't mean that hypothyroidism isn't linked to vestibular disease-for all we know there may be a future study of 1000 dogs with vestibular disease, and when tested all of them are found to have T4 and TSH levels consistent with hypothyroidism-but as far as citing papers like this with a view to blanket treatment (without testing) certainly is NOT evidence based.

So by all means, should be investigated further, and it's great that some dogs have been TESTED, supplemented and responded well but such sweeping statements are based on very flimsy 'evidence' at this stage.....