Considerations for Managing Emaciated Horses

One potential cause of emaciation, other than simply insufficient feed intake, is related to intestinal function.


Body condition, adiposity, and weight can affect a horse’s overall health status. Here, we'll discuss some of the specific health concerns for horses that are too thin (emaciated). 

The biggest concern with emaciation is overall undernutrition. In general, a truly emaciated or under-conditioned horse (with a body condition score, or BCS, of less than 3) isn’t consuming enough nutrients. This could be because the horse isn’t consuming enough feed altogether, or it is consuming feed that has a low nutritional profile. Therefore, in addition to consuming too few calories, the horse may also be deficient in protein, vitamins, and minerals, resulting in an unhealthy situation. While no studies of horses have examined the effects of limiting energy intake (while meeting other requirements) on long-term health, in other species it is well accepted that reduced energy intake resulting in a lean body type (approximate equivalent of a BCS of 4) is beneficial to overall health. With respect to horses, however, the general population interprets a lean animal as malnourished, and the incident can be highly scrutinized.

With emaciation—even if protein, vitamin, and mineral requirements are being met—the concern is the horse not having enough energy reserves in the form of caloric intake to function normally.

Obviously, athletic performance will be hindered if there aren’t enough energy reserves for work. In cases in which emaciation is coupled with increased stresses such as pregnancy or lactation, a low-energy status will be increasingly significant. The body will starve itself to feed the fetus, and in extreme situations the fetus/foal growth will be affected.

One potential cause of emaciation, other than simply insufficient feed intake, is related to intestinal function. Impaired intestinal function is most likely due to parasitic damage or colic surgery. However, there are cases of intestinal malabsorption syndrome in horses that result in idiopathic emaciation. (Intestinal malabsorption is a poorly understood condition where the digestive tract often isn’t formed properly, and nutrients are not absorbed efficiently.) Colic surgery, which may result in resection and removal of parts of the intestine, can also greatly affect overall digestion. Depending on the segment of intestine affected, the horse should be fed accordingly. For example, if a large portion of the large intestine were removed, the horse shouldn’t be expected to consume coarse hay; rather, the diet should consist of a higher proportion of easily digested simple carbohydrates and only highly digestible fiber sources.

If a horse has less condition than desired, it is wise to work with a nutritionist to determine if the horse’s diet is providing the required nutrients. If the diet is adequate, then a veterinarian should be consulted to determine if there are more complicated reasons the horse is not getting sufficient nutrients. Tests such as an oral glucose tolerance test are often used to quantify glucose absorption from the digestive tract. Impaired absorption is highly indicative of malabsorption syndrome. In some cases of emaciation due to impaired intestinal function, it may be necessary to use intravenous nutrition (the direct infusion of certain nutrients into the bloodstream).

It is not uncommon for older horses to lose weight as they age. However, it should be noted that much of these changes are due to loss of muscle mass rather than fat coverage. While keeping an older horse in a suitable exercise program will help maintain the muscle mass, changes with age are inevitable. It is important for horse owners to realize that a lean older horse is not a bad thing, providing it is consuming a high-quality diet and it has sufficient energy reserves to face any challenges (such as changes in the season, work, or disease stress). However, as a horse ages, its teeth become worn and may not break down feed as effectively. Thus, horse owners should ensure that older horses get regular dental checkups and palatable feed. If not, the loss in weight may be due to an inability to properly chew and, therefore, breakdown feedstuffs.

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