Question:  I have a thin Arab mare age 21 with her first ever laminitis episode. She is picky and was a starvation rescue 7 years ago, over the years she has failed numerous feeds trying to keep weight on. She won't eat beet pulp, rice bran, alfalfa in any form or wet foods such as oil. She also doesn't like dry fats like cool calories. I've always had to feed 8 lbs minimum complete feed, but still she has always been a 4 BCS.  Stopped eating Purina, Nutrena and Triple Crown various feeds.

Finally I went to oats, she is a muscled horse, ribs show but no fat deposits or signs of Cushing's. She tolerated 10 lbs oats for several months, then suddenly this laminitis. I was thinking hind gut acidosis, she had gastric ulcers once in the past, but read an article you wrote and she does not have loose stools, fever, etc. She has high quality orchard and timothy hay 24/7, low NSC. But will only eat about 10 lbs, she seems to max out on hay. Her teeth are good per vet, regularly floated and wormed. Bloodwork normal each time tested over the years.

Any ideas what else I could feed to keep weight on? Oats are the only thing she lasted more than a couple months eating in large quantity.

Dr. Kellon: First, I would strongly encourage you to get her tested for Cushing's disease and insulin resistance with an ACTH and insulin. Her age alone makes her high risk and laminitis is often the first sign. Contrary to popular belief they do not have to be fat to be insulin resistant and the classical coat changes of Cushing's are actually a late sign in advanced disease. 

If you haven't already it's important to stop the oats. If she is not getting large amounts of other feed her hay intake should pick up. As for a substitute for the oats, check around at all the feed mills you can find to see if someone can order soy hull pellets for you. They are safe from the laminitis standpoint and have a caloric value similar to oats. Another option is a feed called Stabul 1 that can be obtained through Tractor Supply stores.
You said she doesn't like oil but if you haven't tried CocoSoya you should. Very few horses (or dogs and cats for that matter) can resist it. I would also consider a combination of G.U.T. for its digestive tract soothing support and Absorb-All for assistance in digesting her food well.