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Author Topic: Hereditary (Autoimmune) Hypothyroiditis  (Read 352 times)

LeeRobinson

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Hereditary (Autoimmune) Hypothyroiditis
« on: April 19, 2019, 10:29:46 AM »

Hello -

I’m posting here to find out if anyone in the UK has experience of testing their dog for Hereditary (Autoimmune) Thyroiditis using Jean Dodds lab, Hemopet, in the States?

https://www.hemopet.org/hvemolife-diagnostics/thyroid-testing/

I’d really love to hear about it if so as I’m not sure if it’s worth investigating and exactly how to go about this from the UK, especially as there are so many tests to choose from and all very expensive! A simple T4 reading showed nothing wrong a couple months back but according to Jean Dodds that’s not enough to go by.

We have a recently (9 months with us) adopted Alice, a beautiful rescue tri-colour border collie originally from a farm in Ireland - who rapidly become overweight (from15 to 20 kilos!) and intermittently aggressive (snapping in certain circumstances at home and variably aggressive with other dogs outside) in the last several months - having arrived as an appeasing, sweet natured 3 year old (female) to live with us in our garden flat in London by Hampstead Heath. This change in her temperament has been quite radical and we’re not sure if it has a physiological cause - or is due to the incompatibility of her breed characteristics (not suited to city life) or for historical reasons (how she was treated before)?

With thanks for any advice or shared experience of this testing programme anyone can give.

Lee
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Catherine

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Re: Hereditary (Autoimmune) Hypothyroiditis
« Reply #1 on: April 19, 2019, 11:50:39 AM »

I have not used Jean Dodd's lab but have tested my dogs at the vets in the UK. If you have not already done this, I would have Alice have a full haematology and biochemistry (including electrolytes) blood test done along with a thyroid panel of T4, FreeT4, TSH & TgAb to rule out any physical cause.

Of course the change could be due to the change in environment (probably quite a big one noise wise!) Also although you have a park nearby she may not be getting as much exercise  as running on a farm all day. So, some symptoms could be due to thyroid problems or could be to the change in circumstances.

Also it could be that in the beginning she was not sure of things and then over the months became too sure of herself! What reason was giving for rehoming her to you? I have known some rescue dogs behave well for a few months in their new homes then start to act badly. They are then returned to the rescue centre where they behave okay and then are rehomed and they are okay for a short while and so on.

I would certainly rule out any physical cause first. If it is  her thyroid causing the problems then the medication should hopefully soon make her a calmer dog.

http://cimda.co.uk/smf/index.php?topic=18.0
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Jo CIMDA

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Re: Hereditary (Autoimmune) Hypothyroiditis
« Reply #2 on: April 20, 2019, 09:54:03 AM »

Hi and welcome

I agree with Catherine.  The tests that give a current picture of thyroid status can be done in the UK.  The main tests are TT4, FT4 and TSH.

When you have all three tests done it will show if the thyroid is struggling to produce sufficient thyroid hormone, or if the thyroid is working well.   In a nutshell, a low TT4 and FT4 with a high TSH is considered to be a positive diagnosis of hypothyroidism.  In addition, if a  full biochemical blood test, along with a complete blood count, also comes back clear then the problem is very likely to be behavioural.

Jo

 
Here is some additional information for you:


 ‘More than 95% of cases of canine hypothyroidism are believed to be due to acquired primary hypothyroidism. Destruction of the thyroid gland can result from lymphocytic thyroiditis, idiopathic thyroid atrophy or rarely neoplastic invasion.’  Canine Medicine and Therapeutics by Neil Gorman.

Hypothyroidism or under-active thyroid glands, is the most common autoimmune disease in the dog and is probably evident in most breeds, although the incidence appears to be higher in some breeds than others. This disease is usually a slow process resulting in the destruction of the thyroid glands by antibodies directed against the thyroid (lymphocytic thyroiditis).  As the body only needs less than 20% thyroid production to function, clinical signs of this disease often develop over a lengthy period of time and are so gradual that the owner is not always aware that the dog is slowing down.  The body will cope very well with diminishing thyroid glands, but when the glands have been more than 80% destroyed then clinical signs become more obvious.
 
The thyroid is essential to life; it circulates thyroid hormones to all parts of the body. If replacement therapy is not given to a hypothyroid dog it will die.

 Usually the clinical signs show well before this time and a thyroid blood test should confirm a diagnosis. Thyroid disease is not always simple to diagnose but usually a low TT4 (total thyroid hormone) confirmed by a low FreeT4 (thyroid hormone measurement without protein) and a high TSH (Thyroid Stimulating Hormone) is considered to be diagnostic of hypothyroidism.  (In addition, tests to assess thyroid dysfunction may include: TT3, FT3, autoantibody, TSH and TRH response tests).

Measuring TT4 alone is not enough to make a definitive diagnosis as the dog could be suffering from a non-thyroidal illness (NTI), that is an illness affecting the amount of thyroid hormone within the circulation, rather than a primary autoimmune destruction of the glands.  Non-thyroidal illness should be suspected if the dog has a low TT4 and a low TSH. Whippets and other sighthounds have a naturally lower TT4 than many other breeds but the FT4 is within normal limits.

Note: Several drugs, including prednisolone and diseases such as Cushing’s syndrome, will lower the circulating TT4 levels and this should be taken into account when evaluating the results.  Hypothyroidism is both over and under diagnosed.

Some clinical signs of hypothyroidism are:
Lethargy, mental dullness, unwillingness to exercise,  stiffness in gait – limping, weight gain (obesity), dry scaly skin or greasy skin, excessive pigmentation (hyperpigmentation),  skin lesions, on-going ear problems, coat texture and colour changes, loss of hair particularly on the tail and bilateral, symmetrical  hair loss, signs of premature ageing, irregular seasons - poor infertility and libido, depression (tragic expression), irritability or aggression, intolerance to cold, seizures, voice change (pitch of bark),  muscle weakness, megaoesophagus (weakness of muscles in the throat causing difficulty in swallowing).
On examination your vet may also find that a hypothyroid dog has a slow heart beat (bradycardia), eye abnormalities such as corneal lipid deposits or ulceration: dysfunction of the central nervous system (CNS), such as tilting of head, circling, unsteady gait (ataxia):  Blood analysis may also reveal anaemia and high cholesterol.

The prognosis for dogs with hypothyroidism is excellent, although life-long daily treatment with hormone replacement, Levothyroxine, is required. Giving half the daily hormone replacement dose every twelve hours provides a more balanced level of thyroid hormone throughout a 24 hour period and avoids peaks and troughs. (BSAVA Small Animal Endocrinology)  “Levothyroxine is better absorbed on an empty stomach”.  Canine Medicine & Therapeutics by Neil Gorman

Note: Sometimes dogs with hypothyroidism are prone to other autoimmune diseases.


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