Luckily, there are a lot of steps you can do to minimize the risk of laminitis and founder in your horse.
Founder is a term that describe a change in the structure of the hoof, usually as a result of laminitis. During founder, the coffin bone rotates and the hoof structure is altered. In severe cases, the coffin bone can comes through the sole on the bottom of the hoof. What causes Laminitis and Founder
Laminitis is often caused by a impaired circulation. This impaired circulation causes a decrease in the blood supply to the hoof. This can be from different factors.
Diet is a significant factor in many laminitis cases. Over feeding of grain or lush forage can cause an excess in simple carbohyrdates. These large amounts of carbohydrates then pass through the foregut into the hindgut where the carbohydate begins to ferment in the cecum. This fermentation caused an increase in acidity that kills the bacteria in the cecum. The bacteria then produce toxins that are absorbed into the bloodstream. This then leads to impaired circulation.
If you feed grain, research has shown that feeding a reduced carbohydrate, increased fat type feed can help reduce the risk of founder. Also, consider reducing your grain ration and increasing the amount of forage you provide your horse.
Your horse will also be at higher risk during periods of lush grass growth. The grass makes fructane (simple carbohydrate) all day while the sun is shining via photosyntesis. At night, those fructanes are consumed by the grass to grow or stored in the root system. Thus, you can decrease your risks by grazing during the night and early morning while fructane levels are low. Stable your horse during the day during periods of lush growth or otherwise limit free access to pasture. (we use poly-wire temporary cross fencing to allow only a little fresh grash each day during lush growth.)
Our vet, Elaine Gregg of Horsefeathers Veterinary has suggested that by feeling the digital pulse you can anticipate and prevent founder. The digital pulse is taken by feeling the arteries leading into each hoof. There are 8 measurements -- an inside and outside for each hoof. The pulse is measured how strong it feels. She informs us that 2-3 days before the onset of founder, the digital pulse will get extremely strong. Feeling for the pulse daily (or even weekly) when picking the feet will give you an indication of it's normal state. The digital pulse is hard to find, so you may need your vet or farrier to help you the first few times.
If you feel significant changes in the digital pulse, take your horse off of it's pasture and call your vet immediately! You may be able to prevent the onset of laminitis.
If you suspect founder or laminitis, call your vet immediately. You vet will need to examine your horse and suggest the best course of care for you.
If you have a horse that has foundered, shop carefully for farriers. There are some advanced shoes and shoeing techniques that are available today that can help your horse, I have even heard of some success with derotation of the coffin bone. Some of this can be very expensive.
If you are thinking of buying a horse with founder, or (more-likely) someone is offering to give you the horse, think very carefully about it. It will likely be cheaper and more rewarding to get a sound horse.