Overweight horses are a common issue in New Zealand. Carrying too much condition has many negative health aspects: the most frequent being laminitis, but also respiratory stress, overloading joints, movement difficulty, loss of stamina and the potential onset of metabolic problems.
Excess blood glucose and insulin are factors in overweight animals and can develop into insulin resistance and endocrine complications such as Cushing’s disease or EMS (Equine Metabolic Syndrome) (Frank, 2009).
Equine Metabolic Syndrome (EMS) is important because of its association with laminitis. Obesity and insulin resistance are two important components of EMS. So, increasing insulin sensitivity will lower high blood insulin levels, restore optimal metabolic health and reduce the risk of laminitis and EMS (Grenager, 2021).
When a horse becomes overweight, the effect of insulin is lowered and so it reduces the ability of a horse’s metabolism to convert fat to muscle.
Some horses are more disposed to becoming overweight by nature. The easy-going, laid-back horse that doesn’t get excited and doesn’t have high energy levels, usually called a good doer, is one that is vulnerable to being overweight.
Genetics can play a part, as some breeds and particularly ponies are likely to be overweight, often progressing to EMS. Miniature ponies are known to be very vulnerable to laminitis, EMS and/or Cushing’s disease (Durham et al., 2019). In particular, they are vulnerable to a progressive lipid state that can be fatal.
In essence, too much feed, especially non-structural carbohydrates, i.e. sugars, combined with a low exercise regime will result in a fat horse or pony. The result is quite visible.
Ultrasound can be effectively used to measure stages of being overweight (Westervelt et al., 1976). Also, a mathematical formula can be used (Carroll & Huntington, 1988):
Estimated Weight (kg) =
The original guide was produced by Henneke in 1983 and is a 9-point scale.
 |  |
Reference: Henneke body condition scoring chart.
It is not an option to literally starve a horse or pony by penning or stabling without feed for large parts of the day. Horses need to have some form of feed passing through their stomach or ulcers will be a result (Husted et al., 2009). It is important to act quickly when the first signs of weight gain appear.
Hay is a useful alternative to too much pasture, but it must be washed to remove sugars and a mineral supplement, along with Vitamin E, given as washing removes them.
Use a grazing muzzle or turn the horse out on long pasture, as short or mown pasture has concentrated sugars.
An exercise regime is needed. If a horse or pony can’t be ridden, then provide large free areas to run around, lunging, access to a walking machine or a swimming pool.
Supplementing with chromium has been shown to be very effective and a result can be seen as the fat pads on the neck and rump are greatly reduced. Supplementing with Vetpro Chromium Slim improves metabolic conversion, resulting in less fat being stored and more being converted to muscle (Spears et al., 2020).
For more information, read The Challenges for the Overweight Horse.
| Active Ingredient | Amount per kg | Active Ingredient | Amount per kg |
|---|---|---|---|
| Trivalent chromium | 0.03% | L-leucine | 0.4% |
| L-valine | 0.4% | L-isoleucine | 0.2% |
| Pyridoxine (Vitamin B6) | 0.1% |
| Horse or Pony | Body Weight | Daily Dose |
|---|---|---|
| Overweight Horse | 500 kg | 20 g |
| Overweight Pony | 300 kg | 10 g |
| Overweight Miniature Pony | 150 kg | 5 g |
Enclosed scoop measurement: approximately 15 g.
Obesity and insulin resistance are two important components of Equine Metabolic Syndrome. High blood glucose and insulin levels can increase the risk of laminitis and other metabolic complications.
Some horses are more disposed to becoming overweight by nature. Easy-going, laid-back horses, often called good doers, may be more vulnerable. Genetics can also play a part, and some breeds, ponies and miniature ponies are particularly prone to obesity, EMS and laminitis.
It is not an option to starve a horse or pony by penning or stabling without feed for large parts of the day. Horses need to have some form of feed passing through their stomach or ulcers may result.
Hay can be used as an alternative to too much pasture, but it should be washed to remove sugars. A mineral supplement and Vitamin E should also be provided because washing can remove nutrients. A grazing muzzle or access to longer pasture may also help, as short or mown pasture can contain concentrated sugars.
An exercise regime is needed. If a horse or pony cannot be ridden, alternatives may include access to a large area for free exercise, lunging, a walking machine or a swimming pool.
Supplementing with chromium has been shown to improve insulin sensitivity and metabolic conversion, resulting in less fat being stored and more being converted to muscle.
Carroll, C. L., & Huntington, P. J. (1988). Body condition scoring and weight estimation of horses. Equine Veterinary Journal, 20(1), 41–45. https://doi.org/10.1111/j.2042-3306.1988.tb01451.x
Durham, A. E., Frank, N., McGowan, C. M., Menzies-Gow, N. J., Roelfsema, E., Vervuert, I., Feige, K., & Fey, K. (2019). ECEIM consensus statement on equine metabolic syndrome. Journal of Veterinary Internal Medicine, 33(2), 335–349. https://doi.org/10.1111/jvim.15423
Frank, N. (2009). Equine metabolic syndrome. Journal of Equine Veterinary Science, 29(5), 259–267. https://doi.org/10.1016/j.jevs.2009.04.183
Grenager, N. S. (2021). Endocrinopathic laminitis. Veterinary Clinics of North America: Equine Practice, 37(3), 619–638. https://doi.org/10.1016/j.cveq.2021.08.001
Husted, L., Sanchez, L. C., Baptiste, K. E., & Olsen, S. N. (2009). Effect of a feed/fast protocol on pH in the proximal equine stomach. Equine Veterinary Journal, 41(7), 658–662. https://doi.org/10.2746/042516409×416431
Spears, J. W., Lloyd, K. E., Siciliano, P., Pratt-Phillips, S., Goertzen, E. W., McLeod, S. J., Moore, J., Krafka, K., Hyda, J., & Rounds, W. (2020). Chromium propionate increases insulin sensitivity in horses following oral and intravenous carbohydrate administration. Journal of Animal Science, 98(4), Article skaa095. https://doi.org/10.1093/jas/skaa095
Westervelt, R. G., Stouffer, J. R., Hintz, H. F., & Schryver, H. F. (1976). Estimating fatness in horses and ponies. Journal of Animal Science, 43(4), 781–785. https://doi.org/10.2527/jas1976.43.4.781
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