EMS (Equine Metabolic Syndrome) associates a crest with founder. It is real similar to cushings. My friend had a morgan that would founder every year because of this and she was practically starving him trying to get weight off. They get resistant to insulin.
EMS is defined as a condition of: 1) obesity and/or patchy fat accumulation (crest), 2) insulin resistance, and 3) chronic laminitis in middle-aged horses (8- to 18-years-old).
Breeds especially prone to EMS include:
- Paso Finos;
- Peruvian Pasos;
- domesticated Spanish Mustangs;
- certain warmblood lines;
- some pony breeds.
Here is another article on it http://www.thehorse.com/pdf/factshee...resistance.pdf