No surprise the blood work didn't show anything. From everything I've read and from my good friend's experience, by the time blood tests show cushings, the Owner doesn't need the blood test to know the horse has it
Yes Chasteberry works but it effectivity varies from horse-to-horse and with the severity of the disease.
I feed it to both of my horses with metabolic issues; neither of which have cushings.
I also feed Chia seeds to one of them. I buy people chia seeds as they are much cheaper than when the word "equine" is put in front of chia seeds. Plus I can eat them too.
This is just one of many links if you Google "chia seeds for cushings horses". Dr Chia, Pet Chia, Equine Chia
The rest of diet also has to be changed. Absolutely no grain and no legumes such as alfalfa. Grass hay is best for these horses.
You could read the labels on whatever Ration Balancers are available in your area to find the best one with vitamins/minerals.
If your horse doesn't want to eat his new diet plan, buy some straight timothy pellets and add 1/2 measuring cup to each feeding. I soak them for about five minutes in cold water as they really plump up, once moisture is added.
You might also think about adding Brewer's Yeast to the diet to help alleviate gastric ulcers or hind-gut ulcers. The stress of the disease can cause ulcers -- ask me how I know that
Diamond V YC is made for horses and my vet suggested feeding 2 tablespoons, twice daily. Three of my horses are now on it; the one that colicked in a major way is on something else.
If you can't find equine brewer's yeast, go to the grocery store and buy some. I don't know what the feeding amount would be; it seems to me it would be a little less than 4 TBS/daily.
Be sure to keep up with the hooves. Letting the hooves of metabolic and/or cushings horses go even to 7 - 8 weeks is too long. Keeping up with trims will help prevent laminitic or founder issues with these horses.
My 25 yr old was diagnosed with EMS in 2007 and the 17 yr old with IR in 2010. I've lost track of how many times I've had to modify their diets.
Metabolism is the driving force with these disease (add in the pituitary gland for cushings horses) and as they age, those things change; just like with humans
Good luck and be prepared to tear your hair out as what works now may not work in six months.