Hypothyroid or not....

Re: Hypothyroid or not....

Tom Waterworth — Fri, 26 Jul 2013 22:12:27 GMT

Right sided heart failure - not present as tricuspid valve regurgitation is mild and asymptomatic. Definitely no ascites present.

I do agree that GI disease may be influencing the absorption of the thyroid supplement however but I can find little other evidence of this being a problem - the dog is overweight and so absorption of nutrients really doesn't appear to be a problem to me!

Current plan is to take off meds, and start from scratch again with repeat full bloods, electrolytes, ACTH stim etc and I still suspect I shall be none the wiser!

Re: Hypothyroid or not....

Elisabeth Knappett — Thu, 25 Jul 2013 11:42:15 GMT

I'm going to throw this out there and I'm not being patronising ..... Right sided heart failure?? And the weight is ascites? Absorption problems because of gut oedema - which may explain why there isn't a greater response to the thyroid supplement? And second Noweia - any electrolyte disturbances? Otherwise, very curious as to what's going on...

Re: Hypothyroid or not....

Noweia — Wed, 24 Jul 2013 18:11:58 GMT

What about electrolytes? Bradycardia and gut upsets (suspected IBD) = Addison's?

Re: Hypothyroid or not....

James Laidlaw — Wed, 24 Jul 2013 12:02:56 GMT

Don't forget any active disease process can lower thyroid hormone levels as well.

Re: Hypothyroid or not....

Tom Waterworth — Wed, 24 Jul 2013 11:36:47 GMT

Thanks all for input . I think the main crux of my post was that am still not sure why this dog isn't showing markedly increased T4 levels given the amount of thyroid supplement he is having!

I plan to go back to the beginning and work this up again!

Re: Hypothyroid or not....

John Flynn — Tue, 23 Jul 2013 21:45:38 GMT

I really doubt this dog had/has hypoT4. Those results are fine for a sight-hound.

I know only a Saluki-cross, but here's an e.g. of data off of a website:

"Thyroid Function in Healthy Salukis Shiel, Sist, Nachreiner, Mooney, Thyroid Function in Healthy Salukis, Proceedings, 2008 World Small Animal Veterinary Association Congress

Blood samples were obtained from 335 clinically normal (Country of Origin and AKC) Salukis from 1 to 15 years of age and various levels of activity, and analyzed at the AHDL, CVM, MSU. Analysis of the data showed that Salukis, in comparison to mixed breed ranges, have:

Lower T4 and free T4 values

- which tend to be lower in more active/conditioned dogs

- tend to decrease with age

Low levels of thyroid hormones measured in Salukis likely do not represent hypofunction of the thyroid gland if clinically normal."

http://www.salukihealthresearch.com/SHR%20images/TgAA%20poster.pdf

The approx 15-30% of genuine hypothyroid cases you refer to with "normal" TSH and low T4 probably doesn't refer to sight-hounds, particularly not ones with a "low-normal" TSH level and "marginal-low" T4 based on general canine reference limits.

So I'd stop the thyroid supplement in the absence of any firm evidence for hypoT4 (though I wouldn't go so far as to exclude all possibility of the disease, just seems pretty unlikely to me) or other thyroid-hormone-responsive disease.

TgAA isn't a crazy suggestion, but I'd put a fairly high wager on it being negative.

That leaves a problem list of:

Bradycardia

Obesity

Exercise Intolerance

Pyoderma.

I'd check up on the bradycardia next (I'm guessing you might already have as you said about tricuspid regurg) as this could cause exercise intolerance. An ECG or even Holter would be my weapons of choice, along with some basic bloods, maybe electrolytes and basal cortisol to rule out Addison's .

I'd investigate the pyoderma separate at this stage.

Re: Hypothyroid or not....

Miriam Lodewyks — Tue, 23 Jul 2013 20:30:07 GMT

No disrespect intended towards your clients, but i'd query complience. As my grandfather used to say: "there were no fat people at Auschwitz... and there must have been hypothyroid sufferers among them". So if they're struggling with the weight, they may be struggling with medicating? I may be way off base here, in which case I apologise unreservedly.

Re: Hypothyroid or not....

Michael Woodhouse — Tue, 23 Jul 2013 19:53:50 GMT

Tom - I will send you a private message

Re: Hypothyroid or not....

Tom Waterworth — Tue, 23 Jul 2013 19:32:46 GMT

I think 15-30% of true hypothyroid dogs can have low T4 and normal cTSH so I think in this case - that is not that useful.

I guess my point is - even if the diagnosis was wrong (which I have to say I think it is now)- how can I be getting such low thyroid levels 6hrs after dosing despite giving the dog over the top end dose rate!

The very least I would have thought I would have done is turn this dog hyperthyroid!!

Re: Hypothyroid or not....

Clive Ansell — Tue, 23 Jul 2013 18:30:10 GMT

A TRH stimulation test would be an option maybe? I think as TRH assay is possible too? ecg?

Maybe back to the drawing board and reinvestigate from scratch?

Re: Hypothyroid or not....

Sammy82 — Tue, 23 Jul 2013 18:23:43 GMT

I am no endocrinologist, far from it, but could cushing's cause these symptoms? Not too sure about bradycardia though. Another thought would be a disturbed TSH production, e.g. pituirary problem, rather that actual thyroid pathology? Something like "central hypothyrodism", if such thing excists? Sorry for not being much help.

Re: Hypothyroid or not....

Rob Loxley — Tue, 23 Jul 2013 18:18:19 GMT

[quote user="Utlendigur"]

[quote user="robloxley"]TSH pretty low to start but I seem to remember that 15% of true hypothyroid dogs can have normal cTSH on presentation, and again bit lower range for cTSH in sighthounds.[/quote]

I always thought that in classic hypothyroid dogs T4 was low and cTSH should be high (accepting that some are normal) due to the lack of negative feedback on the pituitary - but it would be unlikely for cTSH to be low

[/quote]

Exactly - evn if you went for a slightly lower 'normal' TSH for a sighthound - hence I'd question the diagnosis, particularly in a Saluki

Re: Hypothyroid or not....

Utlendigur — Tue, 23 Jul 2013 18:13:37 GMT

Re: Hypothyroid or not....

Clive Ansell — Tue, 23 Jul 2013 18:10:25 GMT

I thought cTSH was usually high in cases of hypothyroidism?

Re: Hypothyroid or not....

Rob Loxley — Tue, 23 Jul 2013 18:06:43 GMT

With lack of improvement on decent doses of thyroxine I'd reconsider the diagnosis:

Sighthounds have a lower normal range for TT4 (http://avmajournals.avma.org/doi/abs/10.2460/javma.236.3.302)
TSH pretty low to start but I seem to remember that 15% of true hypothyroid dogs can have normal cTSH on presentation, and again bit lower range for cTSH in sighthounds.