HELP please figuring out Thyroid but meds not working

[Blazergoose]

Backgrounder: Oldenburg mare, 5 years old, owned since weanling, healthy, easy keeper but NOT fat. Shiny coat, happy, alert. Exercise was regular (WT, just started C on flat) until issue, but looks very sound now (August, Sept).

Feed (for 5 yrs): Ration balancer, quality grass hay, and summer pasture access.

Owner: Careful, experienced, knowledgeable on horse care, diet, and VERY careful intro to spring grass, avoids t/o at fall frosts, etc., who has WBs that have NEVER had laminitis issue ever … in all the years I have had my horses in my care (18 years).

Said 5 yr old Oldenburg had laminitic issue in June (off pasture since, or time-rationed) and blood tests in mid-July found very low thyroid and high insulin. X-rays done, seems OK but shoes on anyway. Looks to be feeling perfect. Vet put mare on hypothyroid meds based on blood test at beginning of August, but after 30+ days another blood test shows no change in levels!

Although I can’t ignore the blood results, I wonder if something else is going on???

What’s your experience?
Mare doesn’t display all symptoms, as has shiny coat, chipper, happy under saddle, etc.
Much research seems to debunk hypothyroid in horses, but why the LOW count (5.3)

Please help me!

[ChocoMare]

Two questions: 1 Was Magnesium added or not? and 2 What’s the NSC level of the ration balancer?

[JB]

@Blazergoose

Much research seems to debunk hypothyroid in horses

True, primary hypothroidism is all but unheard of, so that research isn’t wrong.

She sounds insulin resistant, likely compensated (vs uncompensated, which is quickly heading to disaster) which still needs to be controlled

What is the insulin level, what is the glucose level?
EMS/ID - The Laminitis Site

[Blazergoose]

Brook’s Enhancer is .5% magnesium and 2% NSC on morning feed.

Madbarn Omneity premix is 4.5% magnesium on evening feed, added to beet pulp (no molasses) that is wet, and rinsed 3x before feeding .

[Blazergoose]

T-4 is 5.2 below normal range
Glucose is 5.9 in normal range
Insulin is 34.7 above normal range
The I/G ratio is 42

[JB]

@Blazergoose

Brook’s Enhancer is .5% magnesium and 2% NSC on morning feed.

Where are you seeing 2% NSC?

Per the Madbarn listing for this the sugar is 5.5% and starch is 41.48%, which is a DM basis. DM is 90%, which means 5.5% and 42% turn into 4.95% and 37% respectively. That’s insanely high starch. Whether that’s a problem in the amount you’re feeding is the question. But it’s so high I would drop it and use the full serving of the Omneity or better yet, the MadBarn Amino Trace

.5% Magnesium becomes .45% as-fed, which is a measly 2gm magnesium. Often, metabolic/IR/EMS horses are supplemented with 10gm, give or take, depending on the rest of the diet.

I assume the glucose is in mmol/l? The laminitissite says 5.9 would be (slightly) above normal (5.55) But, pretty close

I:G ratio - where does 42 come from? A ratio would mean X:Y, but even 4:2 doesn’t make sense

Essentailly these numbers mean the horse is “compensated IR”, meaning the pancreas is still doing its job. But she’s IR

Can you screen shot the lab results so we can see the units?