Hyperthyroid horse? Possible goiter. Would you consider this T4 as high? How do you treat?

[Color_of_Light]

Ever had a horse with a goiter? How about a hyperthyroid horse? It’s supposedly rare but can happen. The neck of this horse has a lump in the front that could be located near the thyroid, according to the photos of horses with goiters on google. The horse can be excitable. I don’t know if it has sweating problems or not. The weight is good. There is hair loss. The T4 thyroxine level was 2.76 (1-3). That’s over 3/4 of the range. As a person who is hypthyroid myself (I tend to have low T4), if my T4 was 3/4 or more of the range, I’d definitely have a bunch of symptoms. Vet told the owner the level was normal, didn’t notice the neck lump.

Diet is 50/50 alfalfa and grass hay. Alfalfa is a goitrogen, which interferes with thyroid hormone production. Would have thought this horse was low T4, not on the higher side.

If you’ve had T4 tested on a horse, what were it’s levels? Any horses who’ve had high T4? How is this treated?

[Kareen]

Well first of all there is no way to say anything about this case because there are no units to go with your numbers and without units they are just that. Besides the range considered physiological differs widely from laboratory to laboratory and single serum values bear little to no diagnostic value as the levels vary greatly during the day so stimulation tests are usually mandatory. Overall thyroid disfunction in horses is extremely rare and not every lump in the thyroid are will be hormonally active tissue. To make a long answer short you should consult with your veterinarian or if you don’t trust their opinion refer the horse to a clinic that has endocrinology specialists on the team. Best of luck

[Color_of_Light]

I was very curious about the level, so I just called Cornell and spoke to an endocrinologist there. She was very helpful. She said they use that same range (possible test was done there). She said that yes, that is high in the range. She said to be sure to remove all kelp supplements from the diet. The horse isn’t on any kelp supplements, so that’s not the cause. She recommended a full thyroid panel (T3, T4, FT4) and a TRH response test, which might help determine if there is anything pituitary going on. She said horses with high T4 are treated for 4-6 months with antithyroid medication often used in Graves Disease or hyperthyroidism in people, Propylthiouracil.

[Color_of_Light]

Thank you Kareen. The lump might not be related. I also asked the endocrinologist if they test FT3, like is done in people. She said that the only lab in the US that does test of animals FT3 is Michigan State.

[neversaynever]

Had a horse with a benign thyroid tumor. She developed a hard nodule on the thyroid when she was <10 yrs old. Had it looked at by several vets and vet school. It was not a goiter. The horse did not have hypo or hyper thyroidism and it was not a problem. We kept an eye on it and it did not seem to get any larger, smaller then a golf ball but noticeable. She did later develop Cushings in her late teens, but probably not related.

[Personal_Champ]

My mare has a big thyroid and so does her 3 year old son.

She’s been looked at by several vets: my local one, my lameness specialist and a top-notch lameness specialist, who all said not to worry about it as it stays the same. They didn’t even recommend bloodwork as she wasn’t symptomatic. Her weight, coat, energy and sweating are all normal.

[tabula_rashah]

@neversaynever

Had a horse with a benign thyroid tumor. She developed a hard nodule on the thyroid when she was <10 yrs old. Had it looked at by several vets and vet school. It was not a goiter. The horse did not have hypo or hyper thyroidism and it was not a problem. We kept an eye on it and it did not seem to get any larger, smaller then a golf ball but noticeable. She did later develop Cushings in her late teens, but probably not related.

Same here except my mare’s was bigger and when you palpated it, you could move it around and when she was tense it would “disappear”. She’s had it for 5-6 years. Then we started her on Prascend for her Cushings and with in days it was gone??? More than one vet has been consulted and I’ve got no answers about why it is gone. But with her being 23 and still going strong, I’m just going to count my blessings and leave it be at that

[neversaynever]

@tabula rashah

Same here except my mare’s was bigger and when you palpated it, you could move it around and when she was tense it would “disappear”. She’s had it for 5-6 years. Then we started her on Prascend for her Cushings and with in days it was gone??? More than one vet has been consulted and I’ve got no answers about why it is gone. But with her being 23 and still going strong, I’m just going to count my blessings and leave it be at that

My mare’s lump was hard, but it moved also. Never got bigger and she had it for almost 15 yrs. Treatment for Cushings didn’t make it go away with my girl. Hope yours lives a long and happy life!