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Founder and Laminitis

Many factors affect the occurrence of founder and laminitis.


I have a gelding that foundered years before I got him and a mare that foundered several years ago during the fall on grass. Both recovered nicely and I monitor their weight and grazing carefully.

Even with the precautions I take, the gelding has recently shown signs of heat and soreness in his feet again. I have him completely off grass at this point with only free choice hay, salt block and fresh water.

Even though neither of them are overweight, do I need to pull them off spring and fall grass completely? And, if so, when is it safe to allow them restricted pasture time again? Possibly after a hard freeze?


How old are your horses? Are they currently (or were they in the past) obese? There are a couple endocrine diseases of the horse, such as insulin resistance and PPID (Cushings disease), that can predispose to the development of laminitis. If you have not discussed these diseases with your veterinarian, I encourage you to do so.

What is laminitis, exactly? Find out the answers with AQHA's FREE report, Laminitis Treatment.

You are correct in your focus on pasture management. Recent research has demonstrated that excessive carbohydrate intake can initiate laminitis, and under certain conditions, pasture grass is a major source of the non-structural carbohydrates (NSC) that are incriminated. The NSC content of grass varies from season to season, and even changes throughout the day. In general, NSC content of grass will be lower during slow-growth times, and higher during rapid growth. Besides your veterinarian, I suggest consulting with your county extension agent to get some specific grazing time recommendations for your area/pasture type.

Unfortunately, I have had several patients that, no matter how closely the client and I managed their pasture time, required a hay-only diet to prevent obesity and/or laminitis. Another option you could discuss with your veterinarian is the use of a grazing muzzle, enabling your horse to have turnout and exercise, with less concern over grass intake.

-- Dr. Reece Myran
American Association of Equine Practitioners

Want to learn more about founder and laminitis? Read "Living with Laminitis" in the October 2011 issue of The American Quarter Horse Journal.