Fat Horses: Adipose Stores Have Variety of Health Effects

It used to be thought that adipose tissue, or fat, serves as simply a storage form of energy. In recent years, scientists have discovered fat performs a large number of tasks and actually functions as a highly active metabolic and endocrine organ. Adipose tissue produces a large variety of molecules, including inflammatory mediators, hormones, enzymes, and other proteins that have wide-reaching effects on almost every body system.

In human medicine, it is known that different fat stores produce different “sets” of molecules, and that people with excessive fat deposits have higher levels of inflammatory molecules in their bodies. It is also known that humans with excessive abdominal fat stores (rather than fat stores located elsewhere) have an increased risk of developing obesity-related disorders, including metabolic syndrome and insulin resistance.

Horses can also develop those same disorders with perilous consequences. For example, insulin-resistant horses do not respond to the hormone insulin, which means that sugar derived from food is not absorbed by the body tissues and remains abnormally elevated. Affected horses are at risk of developing chronic laminitis—a well-known, life-threatening condition.

According to researchers from Belgium*, horses also have a number of distinct fat deposits throughout their bodies, including the crest, the abdomen, and tissues under the skin around the loin and tailhead. Whether those different fat stores also produce different inflammatory mediators (as in humans) was unclear. The researchers collected and analyzed fat samples to determine what types of inflammatory molecules were produced by different fat stores.

The study authors confirmed that, just as in humans, not all fat deposits in horses are the same. The authors suggested that if more fat is deposited at the crest, it is more detrimental than if it had been deposited around the tailhead, for example.

Considering the increasing prevalence of obesity in horses, acquiring more information on the secret lives of fat cells is an important step in helping horses battle the bulge and avoid obesity-related disorders.

*Brynsteen, L., T. Erkens, L.J. Peelman, et al. 2013. Expression of inflammation-related genes is associated with adipose tissue location in horses. BMC Veterinary Research 9:240.