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Author Topic: Hypothyroidism - therapeutic levels  (Read 192 times)

Hengistbury

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Hypothyroidism - therapeutic levels
« on: August 14, 2021, 06:58:42 PM »

My 11y/o Neardie (Beardie X Border) was diagnosed with HT (non AI)  18months ago - following 3 very violent owner-directed aggressive biting episodes in quick succession and totally dis-proportionate reactions to mild stimulation.  Like a red mist descended, he erupted, then just as quickly he was calm again and somewhat sheepish.  It was only through my Beardie links that I became aware of the possible HT connection and managed to persuade my Vet to run the appropriate blood tests.  Although the lab (IDEXX) concluded 'within average limits therefore non HT', the readings were low average and, by luck, he'd had a routine blood test 6m previously so I was able to demonstrate that the aggressive episodes coincided with a decrease in T4.  That was enough to justify thyroid replacement treatment.  He started on 300mcg Thyforon twice a day (given 1 hour before food) and repeated the blood test.  Vet advised that the aim should be to get the T4 levels in the top quadrant of 'normal' so his dose was increased to 400mcg twice daily. At this stage I was unable to get confirmation of what ideal Beardie levels should be, to be sure this was a necessary and appropriate dose.
Results history fyi -
Date.                   T4 nmol/l.               fT4 pmol/l.           cTSH ng/ml
May 2019.                21
Feb 2020.                  14.5.                         6.8.                         0.16.             Treatment started at 300 mcg Thyforon twice daily
June 2020.                31.5.                       24.6.                         0.03.             Dose increased to 400 mcg
Oct 2020.                   40.3.                       34.4.                         0.03

I have noticed that he seems quite panty overnight through the summer months and have wondered if his BMR is now too high for comfort(?)  We have just re-run the blood test and are awaiting results.
I would appreciate Jo Tucker's comments on these readings in comparison with normal Beardie therapeutic levels.
I will let you know the results of the latest blood test when available.
Oh, and there have been NO aggressive episodes since treatment started!  I have learnt to love my Neardie again!!! He has shown himself to be a charming, sweet lad for the first time since I adopted him as a 4 y/o.  We are enjoying each other's company for whatever time we have left to share . . . .
I thank you for raising awareness of this health issue and thereby saving my Neardie's life!!!

Details - he is neutered and weighs 23.3kg. 
« Last Edit: August 14, 2021, 07:07:15 PM by Hengistbury »
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Catherine

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Re: Hypothyroidism - therapeutic levels
« Reply #1 on: August 14, 2021, 08:23:16 PM »

Is he having the blood tests 4-6 hours post pill? Is he panting all the time?

4mg (400mcg) twice daily may be too much for him.

Idexx say that medicated dogs should have T4 serum concentrations in the range 27.0-70.0 nmol/L.

It is thought, though, that geriatric dogs may need less medication and the Geriatric range is 35.5 - 63 nmol/L.

If he needs his medication reduced you can always reduce by smaller amounts at a time. (It may have been best to have increased like that originally - say to 7mg daily or even 7½mg daily).
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Hengistbury

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Re: Hypothyroidism - therapeutic levels
« Reply #2 on: August 14, 2021, 10:00:06 PM »

Thanks for prompt reply, Catherine.
We always aim for bt at 6 hrs post pill (but nearer 7hrs this time to persuade him to part with his blood!!?!)
Not aware of inappropriate panting during daytime - warm weather and activities may be masking(?)
I know the IDEXX  ranges but understand that these are average across the canine population.  I was hoping to get an idea of Beardie specific readings for a more accurate comparison.  Afterall, IDEXX don't consider him HT at all!
Ummm, hadn't considered him 'geriatric' (!) but useful detail, thank you.
Do you consider such small dosage adjustments will have a significant impact on blood levels?
Obviously, I need to be careful not to risk lowering back into the 'danger zone' - don't ever want to experience that again!!!
I will post latest results, once known, for your consideration.  Thanks for helping.
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Jo CIMDA

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Re: Hypothyroidism - therapeutic levels
« Reply #3 on: August 15, 2021, 10:28:33 PM »

Hi and welcome

Well done for getting your boy diagnosed and treated.  You clearly must have a vet who is willing to work with you and this is so important.

It is well documented that Sighthounds can have lower than usual TT4 and FT4, but I am not aware of any studies in normal thyroid hormone Levels, or optimum replacement therapy levels, specifically in beardies.  The reference range that is used by the laboratories has been established by extensive clinical trials in healthy dogs of all breeds (other than sighthounds) and this is why the ranges are so wide.  This paper might interest you.  It compares various thyroid levels in 7different breeds - Collies- being one category.

https://journals.sagepub.com/doi/pdf/10.1177/1040638715606953

Given that individuals have differing, normal thyroid levels that may fluctuate with age, drugs and hormones pregnancy etc., I think the best way to establish if the hormone replacement therapy is the right dose for an individual dog is to start on a lowish dose and monitor the clinical signs.  It is hoped that an improvement in clinical signs will be seen within a few weeks, but if more improvement is needed then test the TT4, FT4 and TSH and make a small dosage increase.  Continue in this way until the clinical signs, caused by the low thyroid levels, resolve.  Some dogs will need their levels to be higher than others to achieve what would be termed as being 'normal' with no clinical signs of HypoT.  It is considered that some dogs will need their thyroid levels to be up to 25% of the upper reference range.  I personally feel that a hypoT dog should have as low a dose as necessary to achieve normality again.  I have known dogs to be a dose that is too high and this causes many problems including a high grade heart murmur and following a reduction in dose the dog's heart murmur has improved.    So the lowest possible dose to achieve the optimum results and if the dose needs to be adjusted, either up or down, then make small adjustments to the dose and monitor until you reach the optimum dose for that dog.

Jo

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Hengistbury

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Re: Hypothyroidism - therapeutic levels
« Reply #4 on: September 21, 2021, 04:04:04 PM »

OK, now in a position to give an update -
    Aug 2021 results.         30.5.             21.2.        0.03
however the blood was collected at 7 hrs post-pill so direct comparisons are difficult.

I contacted the Thyforon manufacturer, Dechra, to ask their opinion on the observed symptoms.  They were very helpful and provided the following insight - Dechra recommend sampling at 3hrs post-pill for the peak T4 levels (not the 4-6 advised by IDEXX) and they have a 'Conversion Calculator' to estimate the 3hr reading from later-taken bloods.
This gives a 3hr value for T4 as :-
   June 2020       44.5
    Oct. 2020.       57.0
    Aug 2021.        40-48.               Dechra give the target range as 30 - 47 at 3hrs post-pill.   They logged my observations as an 'adverse reaction'.

Correct dosage, it appears, is more an art-form than an empirical formula, and each dog will have a personal response.
Armed with this data, dosage was reduced to 350mcg Thyforon, twice daily at 6am and 6pm.  The night-time restlessness has abated (but the night temperatures have coincidentally reduced with the season) and I was confident all was well.

However, unwittingly, we encountered a 'perfect storm'.
       Hydrotherapy had to be cancelled (we go every 3 weeks) so no feel-good endorphine rush
       A family trip to the New Forest resulted in over-doing the play, resulting in painful joints for the next couple of days (pain-relief increased accordingly)
       In addition to the reduced Thyforon . . . .
and we had 'an incident' - a serious red-mist outburst over a bramble caught in his fur.  (!).  So very sad after 20 months incident-free.
It has made me realise that he is 'not cured' but we are merely 'managing' this disorder and the balance is very fragile and sensitive. 
I suspect an increase in pain was enough to sway the serotonin balance  . . . .
I shall return to 400mcg Thyforon to endeavour to re-gain our balanced state but, in the future, be very mindful of deviating from The Plan - we're are obviously on a knife-edge and his arthritic pain will increase with age and, alas, will not be tolerated with stoicism.

I hope these details will help guide others who find themselves on this journey - I shall always treasure those 20 months and that special bond we shared - ' borrowed time' that could have been denied us.


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Catherine

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Re: Hypothyroidism - therapeutic levels
« Reply #5 on: September 21, 2021, 08:43:35 PM »

Are you giving him his Thyforon on an empty stomach - either 1 hour before or 3 hours after feeding as advised?

Also there is the possibility that if a dog is having too much thyroid medication its body will try to eliminate the medication as quickly as possible and in theory ends up on a lower dose!
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Hengistbury

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Re: Hypothyroidism - therapeutic levels
« Reply #6 on: September 22, 2021, 03:56:43 PM »

Thanks, Catherine.
Yes, given on an empty tum, 1 hour before feeding.
Yes, I take your point about over-dose being expelled quickly.  So , therefore, a reduced oral dose would result in an even lower circulating dose . . . but for how long?  Dose was reduced on 7th Sept.  'Incident' occurred 21st.  I have returned to the higher 400mcg dose.
Sadly, if I can not be sure he is receiving therapeutic levels to suppress the aggression then I can not keep him safe.
I am very troubled by this and fear my options are sadly limited . . . . .
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Jo CIMDA

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Re: Hypothyroidism - therapeutic levels
« Reply #7 on: September 23, 2021, 11:49:58 AM »

Hi

Thank you for all the information.  It certainly can be useful to others in a similar situation.

You are very well informed about hypoT and hormone supplementation so I have nothing to add re dosing etc.

You say that he has arthritic pain.  Is this osteoarthritis?  Is he on something like Yumove as well as pain relief?   If no other clinical reason is found then would you consider him wearing a muzzle when he is out for a walk?  It is so difficult to know, when a dog 'bites back', whether it is a temperament problem, fear, an undiagnosed clinical problem or a hormone problem.

I do hope things calm down for you both very soon.

Jo

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Hengistbury

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Re: Hypothyroidism - therapeutic levels
« Reply #8 on: September 23, 2021, 03:48:07 PM »

Thanks for your input, Jo - appreciate it!
Yes, it's been a steep learning curve and, alas, a painful one!!  His 'incidents' are 'owner directed aggression' and I have been badly bitten.  It's like a red mist and he attacks ferociously over an apparently mild provocation (he resents being man-handled after a poorly managed traumatic injury as a 6m old) usually over perceived anticipated pain (very challenging to groom!!?) then it subsides and he is a bit sheepish.  He is muzzle trained ( I believe all dogs should be) but I have had to be careful that the muzzle isn't associated with anticipated perceived pain so try to minimise usage.  We have established a cooperative routine whereby he has a quick nail file (Dremel)and brush before his walk, without needing to resort to the muzzle.  He has learned to pick up his paws to be dried - everything by cooperation rather than force.
This latest incident is the first since his thyroid treatment began (Jan 2020) and that is what has un-nerved me - I thought it was under control.
He has OA in his hips and hock.  Monthly Osteopen injection, Hydrotherapy every 3weeks, Gabapentin and Paracetamol daily (with Codeine added if he needs a bit extra pain relief). And daily Fluoxetine to boost those seratonin levels. As well as daily Yumove 360 and Hills JD diet.  That regime has worked faultlessly for 20 months. 
As I explained, I think we unwittingly created a perfect storm whereby his pain overwhelmed the hormone control medication and so we returned to square one.(?). Or there could be another underlying factor that we have managed to mask for 20 months . . . .
He will celebrate his 12th birthday early October - something I didn't believe possible in January 2020.   I then need to seriously assess the risks to myself ( and potentially to others - though that has never been a concern to date) and his QOL - if there is mis-trust and fear of handling him and perpetual use of a muzzle - given that his pain will only increase with time . . . . . Such a horrible situation, but he is such a happy-go-lucky Beardie chap in most everyday situations - I walk him with confidence, we have house-guests, he loves to greet people and dogs - yet I have the responsibility to keep him safe and I'm not sure I can when I don't have the confidence that his treatment protocol is fail-safe.
Rest assured, my decision will be a considered one, and made with his happiness and comfort paramount. 
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Jo CIMDA

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Re: Hypothyroidism - therapeutic levels
« Reply #9 on: September 24, 2021, 03:21:47 PM »

'Rest assured, my decision will be a considered one, and made with his happiness and comfort paramount.' 



I have no doubt about that and I truly empathise with you.

You are the one who knows him best, and will make the right decision.  I do hope that it doesn't come to that but.........

It is a very difficult situation for you.

All the best
Jo
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