Editor's note: This article is part of TheHorse.com's ongoing coverage of topics presented at the 2012 Western Veterinary Conference held in February.
The relationship between obesity, equine metabolic syndrome (EMS), and laminitis is like a confusing slippery slope: obesity often goes hand in hand with EMS, and a diagnosis of EMS puts the horse at greater risk for developing laminitis. But not all obese horses develop insulin resistance and some lean horses develop insulin resistance placing them at risk for laminitis. While there's no cure for the latter two conditions, one researcher presented several strategies for reducing the risk of EMS horses developing laminitis at the 2012 Western Veterinary Conference, held Feb. 19-23 in Las Vegas, Nev.
Philip J. Johnson, BVSc (Hons), MS, Dipl. ACVIM, Dipl. ECEIM, MRCVS, professor of Equine Medicine and Surgery at the University of Missouri College of Veterinary Medicine, discussed several strategies for minimizing laminitis risk in horses affected by EMS.
Address Obesity--"Obesity has been associated with both insulin resistance and risk of laminitis," Johnson said. Obesity is reversible. So one of the top things an owner can do to minimize laminitis risk is to ensure their animal maintains a healthy body weight. The first step? Realizing a horse is overweight. As Johnson pointed out, many owners are often "unaware" that their horse could stand to lose a few--or many--pounds.
"Reduced dietary caloric intake coupled with increased physical activity represents the cornerstones of a successful weight reduction program," Johnson said.
Johnson recommends removing sweet feed, grain, and other energy-dense feeds from the diet, and reducing nonstructural carbohydrate (NSC) content in hay to less than 10-12% (more on that in a moment). He recommends feeding approximately 1.5-1.8% of the horse's targeted body weight daily in several small meals throughout the day.
Several commercial feeds designed for EMS horses are new to the market, Johnson said. These feeds have a "certified low NSC content" and can be used as the basis of the affected animals' rations, he said.
Also, avoid feeding obese horses and ponies treats, Johnson suggested.
Maintaining and increasing the level of an exercise program is also recommended. However he noted that this could be precluded by the development of laminitis.
Reduce Pasture Access--"The nature of modern grassland species that are commonly found in horse pastures and paddocks have been genetically selected for purposes of supporting milk production and fattening domesticated cattle and, as such, are characterized by a high NSC content; This is a distinct contrast to the native grassland species on which horses evolved," Johnson said.
As such, Johnson recommends avoiding pasture grazing for EMS horses, especially during the spring bloom, early summer (especially when coupled with rainfall), and during the fall to winter transition (around the time frosts begin setting in); these are the times at which NSC content can be highest throughout the year.
If pasture turnout is unavoidable, Johnson recommends employing other strategies including reduced time of exposure to grass, early morning grazing (when the NSC content is lower), use of a grazing muzzle, strip grazing, strategic pasture mowing, or covering grass with wood chips.
Reduce NSC Intake--An important part of minimizing laminitis risk is reducing the horse's NSC consumption. As Johnson mentioned, feed forage with less than 10-12% NSC concentration. "Selection of a suitable source of hay should be based on results of a forage analysis because it's not possible to guess the NSC content of hay," he stressed. While Johnson said that soaking hay in a "large volume" of water for about an hour can reduce NSC content (this method does not work for all types and batches of hay), a forage analysis is the only sure-fire way to ensure a horse isn't consuming too much NSC as soaking doesn't always remove enough sugar content.
Again, as Johnson mentioned, avoid feeding EMS horses grain, sweet feed, or other energy dense concentrates. Instead, consider a concentrate designed specifically for horses with EMS. Johnson also suggested adding soaked beet pulp (with no added molasses) and rice bran to the diet.
Johnson cautioned that low-NSC forage along might not provide a horse with enough vitamins, minerals, or proteins or meet his daily needs. Thus, he recommends adding a "low-NSC, protein-enriched mineral and vitamin balancer" to EMS horses' diets.
Finally, he noted, consider working with a veterinarian or equine nutritionist to ensure an affected horse's nutritional needs are met, but not exceeded.
Determine if Pharmaceuticals are Needed-- "Nutrition and exercise should be the basis of the weight loss, insulin resistance, or EMS reversal program," Johnson stressed. However in some cases, nutritional support and exercise aren't enough.
In these instances, veterinarians might suggest a medication to help manage EMS and reduce laminitis risk. Johnson noted that, for example, Thyro-L (levothyroxine sodium) is sometimes used to combat obesity by reducing blood plasma lipids and improving insulin sensitivity. Horses typically remain on the drug until a healthier body weight is achieved (generally for about three to six months), he said.
Johnson also explained that preliminary studies have yielded some positive results regarding the use of drugs such as metformin and pioglitazone to address insulin sensitivity, however more research is needed to evaluate these drugs' pharmacokinetics (the activity of drugs in the body from time of administration through distribution in the body through metabolism through excretion) and safety in horses.
When a horse has EMS, he or she is at increased risk for developing laminitis. While there's no cure of EMS, owners can take steps to reduce the risk of the horse developing laminitis. Improve the horse's overall health by combating obesity, reducing pasture and NSC intake, and discuss the use of a medication with a veterinarian.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.