My thoroughbred is a very easy keeper. I'm concerned because he SUDDENLY put on A LOT of weight - mostly around the belly area. I swear he's a mare ready to foal! He is 15 years old, 16 hands high, ridden lightly on the flat about 4 x per week - he's grounded from jumping due to ringbone, and eats 1 measuring cup of Triple Crown Lite 2 x a day. He's turned out all day on grass and a compressed alfalfa bale.
When we bring him at night, my daughter wants to give him only about 1/2 a flake of tifton, but the stable manager wants to keep hay in front of the horses all the time. (It's the only place I've ever boarded that I've had to ask them to reduce quantities of hay fed!!) None of her horses has this problem and they are all retired TB's.
What can I do to get this belly off? If he eats orchard grass he really bloats, as he also does with coastal. The weight was put on suddenly when the grass started to diminish and we threw more hay at him. I live in Florida, so our grass is here longer than other places. I theorized stressed grass plus more hay might have started the gain, but he's really big now and I'm truly concerned.
Compressed bales of alfalfa are in all the pastures so I have no turnout available without hay.
He eats less than anyone but really likes his food - more than most.
Is there a deficiency somewhere in the brain that might be telling him to be in starvation mode and store more fat?
HELP. This weight is not helping his weak back and hocks.
Thanks

Sue Z ; Has he truely gained weight or just looks like he has ? I've read that "hay belly" is caused by hay or pasture that is mature and therefore harder to digest, causing a slow flow thru the gut, thus creating the bloated look. If this is not the case, you can muzzle him with a grazing muzzle , they look pathetic , but they'll keep the weight off him , maybe just keep it on during turn out , don't do it 24/7 . Check for fat build up at the tail head and behind his shoulders and the crest of the neck. Plus if you can get him weighed , so you have a base point to go from ,or you might use a weight tape .Also for the weak back ,if you start making him back up "alot" this is suppose to help build the muscles up and help that area some. This is done better from the ground and I mean you should back up a couple hundred feet ,you'd have to be consistant for this to work ,at least every other day for 4 - 6 months, but start out lower and build up to that as backing is not a horse's favorite thing to do.

If he were my horse I'd have the vet check him for insulin resistance, cushings and things like that - just to be sure given his age. When I had problems keeping the weight of one of my horses (while on stallrest with an injury) I put the hay in a hay bag to help slow down the consumption. Maybe you can do something to make him 'work' harder to get at his food?

Hay bellies in horses are just not due to eating hay, they are more related to poor muscle tone along with that hay. You need your veterinarian's help here. The first thing I would want to check for is pituitary dysfunction (Equine Cushings), as this will cause weak muscles of the abdominal wall, with some overall loss of muscling and sagging of the abdomen. If that is not an issue, more exercise may help. But, again, get your veterinarian involved here.

Thank you for the responses. I will call my vet for a check. The weight gain was sudden - that's what scared us - overnight he bloated like a blimp. I wondered if he had eaten sand and it was gas that caused him to get bigger (I've been through that with my draft cross, who ended up having sand colic surgery). But, I've sanded him and tested and no sand appears in the samples I've done. I will call my vet. Thanks