Could someone please help me with knowing what are the signs in looking for a thyroid problem. What breeding problems can it cause? Also, what is a T4 test?
I have a miniature mare, who is a problem breeder. I have had a hormone test done on day 2 or 3 of 9 day cycle resulting in Estrogen less than 20 ng/ml, and proges. 0.5. But lab wouldnt help explaining results. I dont know if these are even normal.
Some people have suggested Thyroid.r The mare has been bred three regumate and Prostag. induced cycles, HCG given on 6 day, and Regumate started again. Then ultrasounded at 15-20 days, no pregnancies. The vet said he has trouble getting to her ovaries with ultrasound probe, as she starts getting quite agitated about the exam.
I know this is long and complicated, but I am so confused and running out of money........... The mare is 17 by the way and has had this problem all her life , only a couple foals or so. The owners have no breeding history, except she is a problem breeder. PLEASE HELP.........Or recommend someone. email@example.com (My thanks to taking the time to read this)
Posted on Monday, August 28, 2000 - 07:19 pm:
Low Thyroid is the cause of Cushing's disease in horses. Amongst other things, symptoms can be obesity; not shedding out the winter coat in the spring; anestrus (no estrus) or poor reproductive ability (either conceiving or maintaining a pregnancy).
T4 is the test for Thyroxin levels, and is more commonly referred to as "Total T4" or "TT4"
A full outline of Thyroid levels can be obtained on the BET labs site by clicking here
I am unsure at exactly what point in your mare's estrous cycle the blood sample was taken. You indicate "day 2 or 3 of 9 day cycle", but the mare's estrous cycle is 21 days long. The estrus (or "heat") stage is usually 5 to 7 days in duration. During estrus, Progesterone levels should be lower than 1 ng/ml, and in fact should be 0; estrogen levels on the other hand rise the closer to ovulation the mare gets, and reach a peak about 24-48 hours prior to ovulation. In diestrus (out of "heat") the reverse values are true. Progesterone rises to above 4 ng/ml; estrogen levels bottom out. It should be noted that Progesterone levels will not reach maximum heights until at least 5 days after ovulation.
As the mare is an older mare, I would suggest that the Thyroid level may be a consideration, but also that you check the mare for fluid in the uterus both pre- and post-breeding. Older mares can often have a problem clearing such fluid, and it will result in an inhospitable environment for the conceptus, and will result in resorbtion of the pregnancy. Treatment for this can be found by clicking here.
If you have further questions, feel free to ask more!
I just sent off a T4 test on this mare, I'll let you all know........ Thanks, Kara
Posted on Thursday, March 28, 2002 - 11:16 pm:
Jos, I know this is an old list, and maybe you've studied a little since then but Cushing's Disease is hypoadrenocortism, (ie. low cortisol). Although the measurement of T4 (which is mainly used to test for thyroid diseases) is used in conjunction with the ACTH stim test, insulin levels, etc to diagnose cushings, it is not THE recommended test to diagnose it. Cushing's disease in the equine is most commonly secondary to an adenoma or hyperplasia of the pars intermedia of the pituitary. The unjustified recommendation of medical tests and treatments by somebody that is not qualified to give them should be and is frowned upon. This is a problem everywhere and overall your comments are very good, the point is that veterinarians are highly and painfully trained individuals that have at one time learned all this stuff, and they should be the the first to be involved with a diagnosis or treatment. Good Day, Todd
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