Veterinarians Take Cues from Human Asthma Patients to Treat Equine Heaves

New research funded by Morris Animal Foundation may provide new tools and hope for equine asthma sufferers.

Equine heaves, also known as recurrent airway obstruction (RAO), is a debilitating disease that affects more than half the horses in some countries. Equine experts describe it as one of the most commonly diagnosed conditions affecting the lungs of older horses in the United States and Europe. Similar to human asthma, heaves occurs when airborne particles cause inflammation and muscle constriction in a horse’s airway.

While the condition can often be managed through a combination of environmental changes and medical therapy, there is no cure, and commonly used drugs often cause side effects.

Signs of heaves include nonproductive coughing, difficulty breathing and exercise intolerance. The disease can severely impact a horse’s quality of life, which is one of the reasons Morris Animal Foundation (MAF) has supported research to treat it.

Dr. Virginia Buechner-Maxwell and her team at Virginia Tech’s College of Veterinary Medicine have been evaluating a new, promising treatment that uses inhaled magnesium to help open constricted airways.

Natural Elements

Magnesium is a natural element found in the body that causes muscle relaxation and has been used as a treatment for people with asthma. Because the medicine works by relaxing muscles in the constricted airway, Dr. Buechner-Maxwell believes inhaled magnesium could help horses with heaves, too.

With MAF funding, she conducted a small pilot study to see if an aerosol form of magnesium combined with albuterol, another drug that relaxes constricted airway muscles, could improve respiratory function in horses who suffer from heaves.

Both magnesium and albuterol are inexpensive. Albuterol has been used to treat equine heaves and human asthma for many years, but its beneficial effect only lasts 30 minutes to an hour in horses. Dr. Buechner-Maxwell and her co-workers discovered that treating RAO-affected horses with a combination of inhaled magnesium and albuterol prolonged the beneficial effects for at least four hours, which was the total amount of time the horses’ responses were monitored.

Although the study is limited-data were generated from six horses-these results provide enough positive merit that Dr. Buechner-Maxwell is in the process of performing more extensive studies to better define the benefits of combining magnesium with albuterol in the treatment of heaves.

“If we can now determine an optimal dose of magnesium in combination with albuterol or other bronchodilators, we may have a new, safer medication that significantly improves response to treatment without substantially increasing the cost of therapy,” Dr. Buechner-Maxwell says.

She even decided to use the new therapy on her 28-year-old horse, Monty, who was suffering from such severe heaves that she was considering euthanasia. During two and a half months of treatment, Monty seemed to improve, and the amount of medication required to make him comfortable diminished. Dr. Buechner-Maxwell cautions that Monty’s response may have been coincidental, but it gave her hope that the benefits she observed in the study horses would also be experienced by horses treated in their home environment.

“His response is motivation to study this therapeutic approach more closely,” she explains.

Based on her promising results, Dr. Buechner-Maxwell believes this RAO study will lead to an easier, safer and less expensive treatment for horses with heaves.

Tags: equine asthma, heaves

This entry was posted on Thursday, October 15th, 2009 at 12:39 pm and is filed under Horse. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.