Please see heavy disclaimers in title, but I don’t know what other life choices to blame for his last two Cushings tests, and frankly, for all we pay in medications for these metabolic horses, this stuff is a cheap add-on. tl;dr horse went from very high ACTH to low equivocal, vet attributes to supplementing with more bioavailable source of omega-3’s.
27y/o ISH, managed like a Cushings horse since age of 13, diagnosed and has been on Prascend since age 18. Maintained on half a pill twice a day until age 25, then stopped responding; increased to 1 pill twice a day. For most of his diagnosed life, “successful maintenance” looks like hanging out within 2 points either way from the top of the “equivocal” ACTH range. He has not been under that range since he was diagnosed.
In August 2021 he was just above the top of the equivocal range at 79 (seasonal rise equivocal range for August: 20-75.)
In November 2021, he retired from WTC and speedbumps 5 days a week to mostly walking with 10 minutes of trot and canter twice a week. Pretty significant workload decrease.
In January 2022, he was well into the “this horse has Cushings” range at 92 (top of equivocal is 50 for that time period,) highly symptomatic, poor hair coat, depressed, high insulin. At that point my vet was making calls to New Bolton asking what else we could do and I thought we were out of options.
Also at that point, for completely unrelated reasons, I switched his supplements. He has always done better with an omega-3 and vitamin E supplement over the winter, and I’d typically used something flax-based. I wanted to try him on Mad Barn Amino-Trace to see if that could replace a few different things I was feeding. To cover the omega-3 support, I ordered their W-3 Oil. W-3 is a marine derived omega-3 source with added vitamin E. Marine derived omega-3’s are more bioavailable because they are absorbed directly whereas plant-based have to be converted for use.
He hated Amino-Trace so that was the end of that. However: in April 2022 his ACTH was down to 50, which was the top end of “equivocal” for the season. I asked my vet what the heck could explain the horse going from “your horse extremely has Cushings” to “equivocal” in 4 months considering that he was getting less exercise and was out on 12-16 hours of good pasture the whole time. We discussed all of the changes that had occurred in his life in that time period and the only thing that was likely to be associated with lowering his Cushings-related blood markers instead of increasing it was the change to marine omega-3’s. My vet told me I’m not allowed to take him off of the supplement for the rest of his life, and she was buying it for her own horses. I thought it could be one hell of a coincidence and I wanted to see if the improvement was sustained. Note: at this point we also ran his annual thyroid panel, put him back on levothyroxine, and within a week he wasn’t depressed anymore. So a fair number of the symptoms I blamed on Cushings could have been thyroid. (And the Cushings could have caused the thyroid, so here we are.)
So here we are in August. The horse is retired and out on good pasture. I maybe sat on him 5 times in July because it was hot or the footing was bad. He has maintained a BCS of 5 with no dietary modifications, for the first time in 15 years. His ACTH 3 days ago was 21. Antech lists equivocal range for August as 20-75. This is far and away his best ACTH value since he was diagnosed 9 years ago.
I’m not saying marine omega-3’s cure Cushings, but I’m sure not taking him off the stuff. And I’m passing this along not because one horse’s apparent response outside of a scientifically controlled study is the gold standard of data, but because in January I thought my horse was at the end of what we could do for him, and a more bioavailable form of omega-3 fatty acids vs. what he had eaten previously seems to have helped.
