Re: IR Calculator

Lavinia Fiscaletti

Hi LJ,

If you want to run a full thyroid panel -  TT3, FT3, TT4, FT4 - the blood sample needs to be sent to Michigan State University as they are the only lab that can do the equine FT3 test. As Nancy mentioned, the low thyroid is probably due to Euthyroid Sick syndrome, where it is secondary to other causes and will self-correct once the other causes are fully addressed. In Jesse's case, this would be the IR, PPID, possible iron overload and the mineral imbalances in his diet.

The leptin being in normal range points to PPID and diet as the causes for the severe IR status. Definitely no pasture grazing recommended as the risk for laminitis would be quite high. Turnout with a sealed muzzle would be fine. Adding exercise in the form of ground work, if not rideable, would be a plus. Testing and tightly mineral balancing his diet would also be a plus. This would also be the route if iron overload is an issue. The r/s/r of the beet pulp has a purpose - first rinse cycle is to remove iron and other foreign debris, soaking to leach out sugars, final rinse cycle to remove the sugars that have been leached out.


If  PPID is the driving force then you won't be able to get the IR controlled without really tight control of the PPID. His ACTH is still higher than the upper range of normal during the non-seasonal rise period. One option is to wait til April/May and retest to see where it is at the natural lowest-ACTH time of year. If it doesn't drop into the low-to-mid-twenties range then raising the pergolide would be advisable. Re-testing in August would then be needed to see if the seasonal rise was over-riding the then-current pergolide dose.

If he was my horse, I would tighten up the diet and PPID control before adding thyroid meds as it doesn't sound as if Jesse has any excess weight problems that would point to wanting to try to immediately jump start his metabolism for weight loss.

Lavinia, Dante, George Too and Peanut
Jan 05, RI
EC Support Team


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