It sure can be confusing. I’ve been on this journey now for almost 2 years with one of mine (really both as they are easy keeping Fjords). Just had a discussion of test results today my vet.
One is pony insulin resistant and has been for about a year and a half. He was showing abnormal sweating during most of the very hot summer of 2016 and continued to sweat into the winter. Abnormal sweating can be one of the less common symptoms of Cushings. So I insisted that he be tested. Insulin reading was 50 in January 2017. Put him on Heiro, a supplement that is supposed to help with IR. In April 2017, test result had dropped to 40, and now in May 2018, we’ve got it down to 23. All tests were fasting and run thru Cornell.
Other pony’s insulin and ACTH have come back normal on all testing occasions. I do have him on Heiro also, though, since he had one mild lamanitic bout following a case of cellulitis in his legs that was brought on by his Sweet Itch. He seems to have a more sensitive immune system. I am taking no chances. Thyroid results just came back borderline low this spring, so vet suggested a low dose of Thyro-L for him and retest in the fall.
Most of my other management - ultra slow feed hay bags with tested low NSC hay @ weighed 2% daily allotment, muzzles during turnout, no high carb treats or other feed. Low carb ration balancer only. Regular exercise - was already treating these guys as if they were IR even when the numbers technically didn’t say it was so. Vet say this is a big part of why she is very happy with the way these two are doing.
My vet said this crazy weather - late winter into instant hot summer (truly crazy for the upper midwest) - has caused all kinds of very elevated test results in her client horses this spring. (like results as much as 10-20 times what we are getting on these guys)
ACTH results say technically pony #1 is not Cushings. Both vet and I feel he is definitely pre-Cushings if we consider the horse in front of us and not just the numbers in isolation. He has some fat pads on the shoulders and croup. Hair is thick and still shedding (but he is shedding consistently so far). He has been a yak in winter for the 15 years I’ve had him. (He’s 22 now, still acts like he’s 12 or younger.) Although the vet didn’t feel Prascend was warranted yet, I was looking into Chasteberry to help him shed a bit more. Vet highly encouraged that as she has seen good results with it. We shall give it a try and see.
Your thyroid results seem to be on a different scale than mine, so can’t offer much comparison for you on that. Mine was a bit low on TT4 and has been on a low dose of Thyro-L for over a year to help boost metabolism and keep weight down. Although, he is now in the “normal” range, just barely, we are going to up the dose slightly while all the grass is growing like crazy. Will monitor and retest in the fall and maybe adjust back down over winter when the grass is non-existent. Vet has had a lot of success with adding the Thyro-L for IR horses. Even the low dose has kept him at a nice low 5 body score, not bad for a normally rotund breed.
I did ask about testing leptin, but vet said “save your $$$,” and she normally loves to run tests. She says there is very little verified research to tell us what an appropriate result is and even less guidance on what to do with the numbers we would get. So, mainly an academic FYI with nothing you can really manage on a practical basis. I had really hoped this would help shed some light on my not IR, not Cushing pony. He is a ravenous eating machine. Was hoping for a way to tone down his appetite, but alas. One inch hole hay bag and muzzle it is for him. Tough love is hard, but laminitis is horrid.
She also said (and I’ve read in numerous places) that all these hormones play off one another, so when one is out of whack in any way, it can influence test results of the others. That does make a lot of sense. We try as best we can to fine tune all the management and med aspects, but most of all we treat the horse we see in front of us, not just rely on the numbers alone.
Good luck. This is a constantly moving target. My personal opinion is to keep on top of it as it appears Cushings can be years in the making before visible symptoms start to rear their head. I prefer to be a bit proactive when we see the first small signs of trouble with anything.
