New study investigates whether obesity is a risk factor for asthma in horses
An obese horse at Texas A&M University, courtesy of Dr. Michelle Coleman.

Researchers are investigating the link between obesity and asthma in horses in the hope that their findings will improve how the condition is diagnosed and treated.

Asthma is one of the most common respiratory problems seen in horses, diagnosed in all breeds and reportedly affecting between 10% and 20% of adult horses. Obesity is also seen as one of the most important welfare issues in horses, with statistics showing approximately half of all U.S. horses overweight or obese. Morris Animal Foundation-funded researchers at Texas A&M University are investigating the association between these two conditions. If a link is identified, the findings will help improve our understanding, diagnosis and management of asthma, especially in obese equines.

Obesity has been identified as an important risk factor for asthma in humans. While some evidence suggests there also is an association between the two in horses, it has not been fully explored. The main therapy to treat asthma is corticosteroids, but for obese horses those come with a concern for complications, such as laminitis.

“Veterinarians are faced with the concern of administration of steroids to a horse with asthma and end up with a life-threatening complication because of the therapy itself,” says Dr. Michelle Coleman, Assistant Professor of Large Animal Internal Medicine at Texas A&M. “We want to better understand the mechanism of asthma to help guide future studies looking at different therapies or ways to prevent disease.”

For their project, the team will study 60 horses, of any breed, from those brought into the Texas A&M Veterinary Medical Teaching Hospital. Researchers will first assess the horses’ body conditions, identify if they are insulin dysregulated and define their state of asthma. This will be done by listening to their lungs, looking for nasal discharge and examining fluid samples from their lower airways.

The 60 chosen horses will be divided into four groups of 15: obese and asthmatic, non-obese and asthmatic, obese and healthy, and non-obese and healthy. The team will then look for markers of inflammation, including cytokine levels (small proteins released by cells that illicit inflammation). In humans, the levels of cytokines differ between obese asthmatic vs. non-obese asthmatic people.

The second part of the study will examine the horses’ lung microbiota (population of resident bacteria), to see if there are any noteworthy differences in asthmatic horses with and without obesity.

“Obesity and equine asthma are both significant problems for horse health and management,” says Dr. Janet Patterson-Kane, Morris Animal Foundation Chief Scientific Officer. “Knowing more about potentially significant associations between such important conditions has implications for tailoring prevention and treatment methods to individual animals. Most importantly, if this association exists, we might be able to identify horses that are at higher risk to help their owners prevent disease or at least intervene earlier.”