Equine practitioners are commonly faced with communicating to clients that their horse (or horses) are too fat. This can be a delicate subject, especially when an owner feels they have been feeding appropriately and “like” their horse’s plump weight. Some horses tend to put on fat with even scant groceries, while others do so because of overfeeding and inadequate exercise. Accumulation of adipose tissue exerts multiple adverse effects on body systems and organs, leading to chronic inflammation, metabolic and insulin dysfunction, and an increased risk for laminitis.
At the September 2020 BEVA (British Equine Veterinary Association) conference, Phillip Ivens, MA, VetMB, CerEM (Int Med), DECEIM, MRCVS, gave a presentation on considerations important to managing equine obesity. Ivens pointed out that while obesity is common in equine metabolic syndrome (EMS) cases, not all obese horses develop EMS but often experience other adverse health effects. Besides the more widely known risks of laminitis and difficult recovery as well as poor performance related to obesity, other health-related problems can develop due to excessive fat deposition, according to Ivens:
- Increased pro-inflammatory cytokine production
- Increased blood pressure
- Increased risk of hyperlipemia, hypertriglyceridemia and hyperglycemia with critical illness
- Increased orthopedic disease such as osteoarthritis
- Increased risk of OCD in foals born to obese mare
- Decreased mare fertility, altered estrus cycles and subfertility in stallions
- Inappropriate lactation
- Mesenteric lipoma and small intestinal strangulation
- Altered behavior
For horses with regional adiposity and/or cresty neck scores, obesity is easiest to identify. Laboratory testing is helpful when combined with clinical observation. Useful tests include leptin, adiponectin, basal insulin, oral glucose challenge, Karo syrup challenge, ACTH and TRH stimulation to assess presence or absence of PPID.
Counseling clients about weight reduction is essential, with a goal of 0.5%-1% reduction in bodyweight per week. It helps for owners to keep a record of a horse’s progress. Weight tapes can be useful for comparison measurements of an individual horse to itself. In difficult cases, pharmaceuticals such as levothyroxine and/or metformin can help, but modification of feeding regimens coupled with improved exercise programs are critical to achieving results.