Question
My 23-year-old pony mare, Isobel, is overweight—body condition score of 8.5+. She gets some exercise in the fall and winter through foxhunting, though for her it is more hilltop-lounging than full-out gallivanting. I know she needs to lose weight, and now’s the time. She has access to dirt-quality pasture so she gets free-choice orchardgrass/alfalfa hay in the field daily. She also receives two cups each of a senior feed, fat supplement, and ration balancer. As far as supplements, she gets Nano-E at a rate of 4 mL per day. She has a history of muscle atrophy and soreness, presumably due to PSSM. She is sound and healthy otherwise. Where do I start?
Answer
Based on Isobel’s age, it would be worthwhile to have your veterinarian test for pituitary pars intermedia dysfunction (PPID, Cushing’s disease) as muscle loss and poor performance are associated with this age-related condition. If she has PPID, an effective medication for slowing the progression of the disease is available. I have woven general management and diet recommendations for PPID and myopathies into this response, which focuses primarily on body condition.
Maintaining an ideal body condition score of 5 or 6 and instituting a regular exercise program will improve the mare’s overall fitness and stamina. Provided Isobel is sound, the importance of regular—almost daily—exercise cannot be stressed enough. In a recent study, even light exercise appears to reduce the risk of endocrine abnormality.
A closer look at the quality and quantity of forage offered is needed as this represents the majority of the diet. In this case, good-quality orchardgrass/alfalfa hay is likely to be supplying Isobel with too many calories. Another hay should be offered, and one made from only grass species would be best, as she doesn’t need alfalfa or any other legume in her diet currently.
The amount of hay consumed is also important for maintaining caloric balance and digestive health. In most cases, a reduction in the amount of forage available and lower quality forage is needed to achieve weight loss. Do not feed free-choice hay to your pony; instead, aim to feed about 1.5% of body weight per day. Find a way to slow hay consumption, such as through double- or triple-bagging haynets to create small holes or purchasing specially designed haynets to limit bite size.
A ration balancer is an appropriate option when offered at the minimal amount you’re feeding. Two cups per day of a senior formula may not be meeting the manufacturer’s recommended feeding rate; double-check the amount you’re feeding when you can. An increase in senior feed or switch to a more concentrated source of vitamins and minerals may be needed to provide optimal nutrition.
Dietary fat can be beneficial for PSSM horses, but it is not advised for overweight horses. I suggest removing the high-fat supplement from the diet at this time. A reduction in the senior feed may be needed, too, though feeding a small amount can help with mixing supplements.
Nano-E is an excellent supplement to support immune and muscle health. Another supplement to consider is EO-3, a marine-derived omega-3 fatty acid supplement that provides anti-inflammatory benefits.
