Kimberly,

Insulin is a moving target. It responds to the glucose (and protein) load presented to it. Fasting insulin with no glucose or amino acids being absorbed should be less than 8 uIU/mL.

Severely restricting calories puts the body in alarm mode. It will preserve precious glucose intake for heart and brain. To do this, the horse's body goes into insulin resistance (those tissues don't require insulin for glucose uptake). Obviously this on top of already existing insulin resistance is not a good thing!

I would not go below 1.5% of current body weight, or 2% of ideal body weight. True Mustangs of Spanish origin are definitely insulin resistant because of their heritage. The best thing you can do for them is plenty of exercise - ideally 20 miles/day.
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001