Thyroid UK
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Weaning off Levo help please + test results

Cannot get any help from vets , what would you do if these were human results ?

Results October 2017: first thyroid test , not on any meds

T4 : 33 ( 13-52)

FT4 : 13.9 (7-40)

T3 antibodies : 0.7 (<2.0)

T4 antibodies: 0.9 (<2.0)

TSH: 0.12 (<0.41)

TGA: 114 (<200)

T3: 109.4 ( 20-206)

FT3: 4.7 (3.7-9.2)

January 2018, Thyroid retest , not on any meds : ( some mild symptoms of hypo )

T4: 17.3 ( 10-55)

TSH: 0.21 (0.01-0.06)

FT4: 8.5 (6.6- 40)

TGA : 6 negative ( no range given )

T3: 70.4 (20-206)

FT3: 5.1 (3.7-9.2)

MCHC: 32.7 (32.6-39.2)

Triglycerides : 1.84 ( 0.30-1.20)

After this test we started Levo 400mcg twice a day (mid normal dose ), and improvement came . Then 6 weeks retest :

March 2018: on Levo 400mcg x 2/ day apart from food , no ther meds :

Total T4: 44 (11-60)

TT3: 1.1 (0.8-2.1)

FT4: 19 (6-42)

FT3: 3.5 (1.2- 8.2)

T4 antibodies 6 ( 0-20)

T3 antibodies 2 (0-10)

TSH: 0.04 (0.00-0.58)

TGA : 8 ( 0-35)

Based on still quite low fT4 we increased the dose to 600mcg twice a day ; he worsened very quickly so after 4 weeks rested and results supported the symptoms :

April 2018:

TSH: <0.03 ( <0.41)

TotalT4: 32.7 (13-52)

FT4: 10.8 (7-40)

Dropped the dose down to 400 again ; does dropping the dose take 4-6 weeks to work , same as increase ?

I would like to wean him off the thyroid meds as he never had TGAs ? I am suspicious dietary / nutritional deficiencies may have caused the drop in TH in this otherwise young healthy dog ?

Do I decreased the dose every 4 weeks and wean off slowly ?

B12 , folate and iron/ ferritin tests pending !

Vit D not possible to test in dogs .

Currently giving good multivitamin apart from Levo.

Please guys help me understand these results ?

I suspect the higher dose of Levo was too much and he started converting T4 into rT3 ( not possible to testin dogs )- we call it “dumping the excess T4 which will result in hypo ; dogs almost impossible to get thyrotoxicosis.

Thank you so much


12 Replies

I don't understand why you lowered the dose in April after such a low result. I would have increased it. I also have a hypo dog. But I would have increased it if it were me, too.


I decreased the dose because his results and him also were better in the lower dose - if you give too much to a dog , they will just dump it - becoming more hypo - which is what happened and if you note his TSH : it supports it - it should have been higher when fT4 dropped ; does it make sense ?

If I learned correctly here - too much T4 will results in being converted to rT3 rather than T3 to avoid hyper ; and I believe that’s what happened

600mcg is quite high dose ( 20mcg per kilo of weight ; normally they are medicated 10-15 much/ kg)


Too much T4 in humans will convert to rT3, yes, but that doesn't mean that the FT4 level drops. It doesn't. It stays high unless the dose is dropped. And, in humans, 1 month would not necessarily be enough to raise the TSH significantly. But, I don't know about dogs. Sorry. :)

I would just say that increasing the dose from 400 x 2 to 600 x 2 seems like a huge increase, even for a dog.


I agree I think it was a big increase , and that explains why he got worse in that dose relatively fast - in matter of days - I learnt from my other hypo dog that behaviour is a fast indicator - one missed dose and “weird” behaviour comes right away -

I now have a third dog diagnosed hypo ! - this is why I’m thinking something else is wrong - they can’t be all hypo !


They all also shared hematology abnormalities - pointing to iron/B12 anemia - testing those this week , hopefully that gives us some answers and I’m thinking that if they do come low in those - could they be low in other crucial vitamins/ minerals that are needed for normal thyroid function ? Their food contains very little actually so I will be supplementing and changing food and will try with the newly diagnosed dog to sort his nutrition out first and seee if his thyroid function improves


It does seem strange that they are becoming hypo one by one. Does their food contain soy?

But, I agree with you about the huge increase, that could have caused a lot of problems.



Unless any members are qualified vets then I don't think anyone can help and I wouldn't rely on any information given here.

There is a pet forum with a dog section, also a sub-section for Health and Nutrition, and I know one member is a vet so it may be worth posting on there.

1 like

Thank you but I am facing same struggle with vets as you guys with doctors ; and even though I found one vet who “believes me “ and cooperates but he doesn’t have the answers either ; no one does and I feel like I’m fighting this battle all by myself ; I ended with 6 dogs with low thyroid function so I am looking at other possibilities causing this - they were all on the same food - nutritionally inadequate - so I am wondering whether that’s causing decreased TH production or/ and conversion problems ?


Why not give that forum a try, you've nothing to lose and you might be pleasantly surprised.

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I will thank you 😊


There was someone here a while ago who had their dog on T3 only and it did well. Feed raw if you can.

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I have tried raw but it just doesn’t work with my lifestyle , amount of dogs and food needed and quality here is rubbish ! I have 80kg Great Dane who needed 5kg of raw a day ! It was too expensive - I have to find dry alternative and supplement if needed

T3 I considered but not an option due to cost hence why I want to make sure they convert as well as they can - if I can achieve that with correct vitamin / mineral levels

Thank you guys for all your input it s much appreciated as I wouldn’t get this much insight from vets or dog forums


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