Hypothyrodism

[Lucy]

My 13 year old collie had a vestibular attack 6 weeks ago and on undertaking a full range of blood tests it was noted that his thyroid function was greatly reduced from 12 months ago.  It was 16, a repeat test of the thyroid function was done Tuesday 6 weeks after the last blood test and it has dropped to 15.  The sample was sent off for full TSH function etc and has come back today as TSH at  1.78,  I hope that's right I haven't got the full results only the TSH levels.  My vet is starting him on Thyforon 200mg. 

Up until last September he was competing at flyball and I retired him in September as he was 13 in March.  He was a fit, healthy dog who exercised regularly.  Since the New Year he has become letheragic, had the vestibular attack, head tilt, eye rolling, falling over, his gaining a lot of weight and has had some senile type moments.  He is raw fed and because he has been on reduced exercise, I had reduced his food by 100g and he is still gaining weight.  His coat is dull and lacks its normal sheen, but I wouldn't say its thinning just lacking its normal sheen.

He is also on vitafyllin for his vestibular disease but having done a limited amount of research I'm unsure whether his episode was vestibular or thyroid induced.  He has damaged lungs due to getting kennel cough when he was younger that turned to pneumonia so has an inhaler once a day which I'm told the vitafyllin may help.

I was posted towards this site to get some help and advice on how to go forward with Oz and I'd really appreciate any help and advice on this illness and how best to treat him and feed him etc.   

I lost his son at Easter who was being treated for pancreatitis but it was a tumour and we had to put him to sleep at 11 years old.  His dad seems to have aged quickly and all this has happened or come to the surface in that time. 

Any help would be greatly appreciated.

Thanks

Lucy

[Jo CIMDA]

Hi and welcome

I am sorry your collie has vestibular disease and hypothyroidism.  Vestibular disease will often spontaneously resolve within a few weeks but if he also has hypoT at the same time this will not help.  HypoT can be a primary disease or secondary to another condition that is affecting the thyroid.

  A reduced thyroid hormone affects all parts of the body and when replacement therapy is started you may see a good improvement within days and certainly after a couple of weeks he could be back to his old active self again with many of the clinical signs disappearing.  The skin and hair condition may take a while longer but it will all resolve in time.   

His TSH result isn't particularly that high but it indicates that the thyroid might be struggling.  A good diagnostic panel is Total T4, Free T4 and TSH.
When a young dog develops primary hypoT  it is usually caused by an autoimmune destruction of the thyroid glands but in an older dog this might not be the case and it might just be a wearing out of the gland because of advancing age.  The treatment is the same and that is with thyroid hormone replacement and if the dose is correct the dog will become fit and healthy once again.

I am so sorry you lost his son earlier this year,  and I understand that it makes dealing with this a lot harder, but the prognosis for a dog with HypoT is excellent so you should see improvement soon.

Below is an extract from my notes:

Jo



Hypothyroidism – An underactive thyroid gland
'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

[Lucy]

Hi Jo

Thank you so much for your reply, I had seen it but was unable to reply till tonight.  It was really reassuring and I'm pleased to say he showed signs of improvement like you said within 48 hours and a week later, is much brighter and steadier on his legs.  He is due a blood test in 3 weeks to check his levels but so far touch wood. 

We will then look at his dose and if its correct and talk about the vitafyllin dose as well.  Bit unsure what to do there whether to leave him on it as it helps his chest too as he has damaged lungs due to kennel cough when he was younger and has an inhaler for that but I'm told the vitafyllin helps bronchial tubes too.

Once again thank you very much for your response and help.

Kind regards

Lucy and Oz 

[Jo CIMDA]

That's great news Lucy.   Oz should continue to get even better now.    As long as the Vitafyllin isn't causing any adverse symptoms then it make sense to keep giving it to Oz.

Great stuff!!!!

Jo