Editor's note: The myriad of veterinary seminars one can attend could consume tremendous time and resources. Yet, the information available from experts in various equine fields is invaluable and in many ways helps ensure that practitioners keep up with the latest medical and surgical findings in the equine industry. With that in mind, each month EquiManagement is bringing you synopses of interesting presentations from excellent conferences.
One of the more frustrating syndromes to deal with is the overweight horse. Many obese individuals become that way due to inappropriate feeding practices by their owners coupled with lack of exercise; some breeds are more prone than others. At the North American Veterinary Conference (NAVC) in Orlando in January 2017, Anne Wooldridge, DVM, MS, PhD, DACVIM-LA, of Auburn University’s College of Veterinary Medicine, spoke about how to control this difficult-to-manage health problem.
She stressed that dietary management of EMS relies on reduction of both calories and carbohydrates along with careful weighing of the food to ensure that desired quantities are fed. Wooldridge recommends feeding good-quality grass hay at 1.5-2% of body weight and monitoring body condition scoring and weight loss. If the horse doesn’t lose weight after a month, the amount fed should be decreased by 0.25%, and similarly each month that weight objectives aren’t achieved. An objective is for a horse to lose 0.5 – 1% of its body weight each week. A horse should never receive less than 1% of body weight in forage, she said.
She also suggested other important strategies for weight loss and control.
- Restrict pasture either with stabling in a dry lot or use of a grazing muzzle, which lessens pasture intake by 30-80%.
- Use a slow feeder hay bag or bale box to lengthen how long it takes for a horse to ingest hay. The smaller the opening, the slower the intake; 3-4 cm is a good size to regulate consumption rate.
- Eliminate supplements when possible. If some supplementation is necessary, then only offer complete feeds that are high in fiber but low in non-structural carbohydrates (NSC).
- Soak hay for 30-60 minutes and pour off the supernatant – this reduces NSC by 38%, but only reduces digestible energy by less than 7%.
- Supplement grass-restricted horses with 1,000 IU of natural vitamin E per day as well as with a balanced vitamin-mineral supplement.
- Exercise at trot and canter for 30 minutes, 5-6 days per week if the horse has no lameness problems. Condition the horse gradually to be able to accept this level of exercise. Aerobic conditioning helps to burn fat while also training the body to metabolize adipose tissue for energy.
- Where feasible, set up feeding stations in turnout to encourage an appropriate amount of walking to access food.
Wooldridge noted that some horses are lean, yet still experience insulin dysregulation. Her recommendations for managing these individuals include:
- Control NSC intake to less than 10-15%.
- Test hay and soak it to remove water-soluble carbohydrates (sugars and fructans). She points out that alfalfa hay is low in NSC and may provide appropriate calories for a lean horse.
- Use fat sources such as oil for calories to maintain body condition of a lean individual. Note that rice bran is high in NSC content.
Medications may play a role in EMS management but must be combined with diet and exercise:
- Levothyroxine increases insulin sensitivity and calorie use by increasing metabolism.
- Metformin also increases insulin sensitivity but because bioavailability in horses is only about 7%, it is recommended to feed metformin within an hour prior to offering a meal.
- For horses experiencing both EMS and PPID, pergolide is useful.
Editor's note: Having this science to help you explain equine weight loss to horse owners can be a benefit to them "pushing back" against restricted feed intake and additional exercise for their horses.