This horse is demonstating a laminitic stance. These horses may lean back on their hindquarters to relieve pain in the forefeet. They may also lay down for pain relief.
Is your horse at risk for laminitis?
1. Is your horse overweight? Is he an 'easy keeper' ?
2. Does he show signs of Cushing's syndrome?
shaggy hair, loss of muscle mass, lethargy, sickly, abnormal lab values
3. Does he have a cresty neck?
4. Does he have founder rings on the hooves?
5. Has he had bouts of laminitis?
6. Is is a pony or have relatives with laminitis?
7. Is his carbo load possibly too high: excess grain or overfeeding pasture.
It is difficult to know the level of risky non-structural carbohydrates in any grass without testing so limited pasture is recommended for many horses, especially those at risk. Muzzles can be helpful.