I was talking with Sheila, my equine management associate here at Desert Equine Balance, this morning when we got on the topic of "big" horses and some of the different management issues they have.
Draft horses generally have been bred for strength and size rather than being mainly a refined version of a more naturally evolved light horse. They were bred for heavy work on a regular basis - pulling or carrying heavy loads - and weren't really expected to jump things or carry us on adventures around the countryside.
The appeal of these large purebred drafts and draft crosses can't be denied. For the most part they seem laid back, willing to please and are beautiful to look at. As more and more draft crosses show up at rescues, more people make the decision to bring one home as their primary riding horse. I find I'm working with more and more of these horses as time goes on and some owners find themselves with big horses that just aren't doing as well as they should.
Draft and draft crosses are susceptible to a condition called EPSM - Equine Polysaccharide Storage Myopathy, a muscle condition that causes weakness and a specific type of rhabdomyolysis - known as "Sunday Morning Disease" to working draft horse owners.
Some new large horse owners have heard that drafts may have special needs or requirements and spent time preparing for their "gentle giant". They can be prone to insulin resistance (IR) and poor performance related to stiffness and gait abnormalities related to the EPSM. Obesity is sometimes not "noticed" because of their large size. Compare the large yet fit Clydesdales above to the fat workhorse here - http://www.flickr.com/photos/78953809@N00/1688846112/.
Some draft/draft cross owners have told me "my horse doesn't have EPSM". It's possible that the question isn't "if" the horse has EPSM but "when" it might show up. But with appropriate nutrition and management, the effects of EPSM don't have to affect your large horse.
- Monitor your big horse's weight and condition frequently. http://www.draftresource.com/Draft_Wt_Tape.html has an interesting discussion on measuring for weight; useful as most weight tapes don't go around.
- Avoid grain unless your horse is working hard. Use NRC guidelines to avoid over feeding your draft horse.
- Feed low sugar/low starch hay - try to buy tested hay or learn to test it yourself. See http://desertequinebalance.blogspot.com/2006/08/analyzing-hay-and-feeds.html
- Exercise your draft horse every day. Owners on the ESPM group report seeing more symptoms when they skip exercise. "Turnout" does not have the same effect as structured exercise.
- Learn all you can about diet, EPSM and caring for draft horses.
EPSM: List for owners of horses with EPSM, a common problem of big horses. Lots of information from owners of big horses who have or want to prevent problems.
Eleanor Kellon, VMD is a frequent visitor here and works with list members on diet and supplements. Many owners have been using a low sugar/low starch diet along with ALCAR (Acetyl L-carnitine or plain L-carnitine) and other supplements to effectively manage EPSM symptoms.
Rural Heritage Vet Clinic - Dr. Beth Valentine
Lots of background on draft horses. Dr. Valentine is an advocate of a high fat diet for draft horses.
Information on muscle biopsy to diagnose EPSM
U of Minnesota PSSM testing information
Information on both genetic testing and muscle biopsy, plus a "decision tree". PSSM is similar to EPSM, seen most often in Quarter Horses but also in draft horses and other breeds.
NRC Plus - online nutrition courses by Eleanor Kellon, VMD.
NRC Plus is the basic and gives the framework for the advanced courses that follow.