High Alert: Obesity Puts Horses at Risk for Asthma

In addition to the already long list of reasons why horses should be kept in moderate body condition, a new study shows that obesity is an important risk factor for asthma.^*

According to Texas A&M University researchers, overweight horses had ten times higher odds of developing asthma than horses at moderate body weight. Other risk factors such as age, breed, sex, diet, and stable management were all evaluated but, surprisingly, none of those was found to be significant in this study.

“The association between obesity and asthma has never been reported in horses prior to this study,” said Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research, highlighting the potential importance of these data.

The study included 37 horses diagnosed with mild to severe asthma based on clinical signs such as coughing, exercise intolerance, and nasal discharge. Clinical testing was performed on these horses to confirm clinical findings. Researchers also used 74 horses as controls. In this study, obesity was defined as a body condition score of 8 or 9.

As explained in the study, obesity is a significant risk factor for asthma in humans, and research in this field has recently escalated. Obese humans reportedly have “more severe disease, persistent airway inflammation, and poorer response to treatment with corticosteroids compared with nonobese asthmatics.”

While the mechanisms that link obesity and asthma remain unclear in both horses and humans, scientists believe that obese individuals have an increased systemic inflammatory state and an altered metabolome. Metabolites are the end products of cellular regulatory processes, and the metabolome is the total number of metabolites within an organism. Analysis of the metabolome provides a direct measure of cellular activity and physiological status.

Considering the clinical importance of asthma, poor performance in mild cases, and poor quality of life in more severe instances, additional research is warranted. Corticosteroids play a key role in medical management of asthma and, if obesity makes asthmatic patients less responsive to these drugs, horses may be left with uncontrolled disease.

“The first step in managing your horse’s body weight is to recognize that your horse is overweight. As simple as this sounds, studies show that owners often underestimate body condition score,” Crandell said. If you’re unsure how to assign a body condition score, recruit a more experienced horseperson or your veterinarian to help.

Next, evaluate your horse’s diet. How much forage, by weight, is your horse consuming? Is it in the 1.5-2% body weight range? Does your horse need a grazing muzzle while on pasture, or should he be removed from pasture altogether?

“Look at the amount of concentrate you are providing. Can concentrates be replaced with a low-intake ration balancer or a vitamin and mineral supplement to reduce calories? In many instances, the answer to this question is yes,” said Crandell.
These questions can be used to start a conversation with your horse’s team of health care professionals. Do you have a specific question about your horse’s diet? Ask a nutrition advisor today!

^*Thomas. S.J., C. Navas de Solis, and M.C. Coleman. 2021. Case-Control study of risk factors for equine asthma in Texas. Journal of Equine Veterinary Science 103:103644.