While lower airway disorders in horses—think pneumonia or equine asthma—usually necessitate medical treatment, upper airway issues such as recurrent laryngeal neuropathy (“roaring”) or epiglottic entrapment are generally treated surgically, right? In many cases, yes. But researchers recently determined that, in sport horses, medical treatment might be useful for an upper airway disorder that commonly affects racehorses: dorsal displacement of the soft palate, or DDSP.
Fe ter Woort, DVM, DVSc, Dipl. ACVIM, of Equine Sports Medicine Practice, in Waterloo, Belgium, shared the results of her recent retrospective study on treating DDSP sans surgery at the 2018 American College of Veterinary Internal Medicine Forum, held earlier this year in Seattle, Washington.
Displacement occurs when the horse’s palate shifts on top of the epiglottis and partially obstructs the airway. This leads to clinical signs such as respiratory noise, coughing, and poor performance. It’s most common in racehorses but can also appear in sport horses.
Ter Woort said researchers have suggested a link between DDSP and lower airway inflammation in racehorses, but the concept hadn’t been explored in sport horses. So, she and colleague Emmanuelle van Erck, DVM, PhD, Dipl. ECEIM, reviewed three years of medical records from their clinic to identify instances of DDSP treated medically.
Over the three years veterinarians performed 270 overground endoscopy examinations on sport horses presenting with cough, respiratory noise, and/or poor performance; 27 were diagnosed with DDSP. Of those, DDSP was associated with coughing in 22 horses and respiratory noise in four horses. One horse exhibited neither.
Veterinarians performed a tracheal wash (flushing saline into the windpipe and drawing the “wash” back up with a syringe) in all the DDSP horses and a bronchoalveolar lavage (BAL, injecting a horse’s lung with sterile fluid before drawing it back out again) in 24 of these horses to look for evidence of inflammation. Ter Woort said they found evidence of tracheal inflammation in 25 horses and lower airway inflammation in all 24 horses that underwent a BAL. From the tracheal washes, bacterial and fungal cultures were positive in 14 and 16 horses, respectively, she said.
Veterinarians elected to try medical therapy in 25 of the 27 DDSP horses. Ter Woort said treatment included:
- Topical anti-inflammatory treatment with furacine (the Belgian version of nitrofurazone, in a gel form horses swallow) and dimethyl sulfoxide (more commonly called DMSO);
- Inhaled corticosteroids;
- Bronchodilators; and
- Antimicrobials when the culture revealed the presence of pathogenic (disease-causing) bacteria.
Additionally, they instituted environmental changes in horses with equine asthma, including ensuring they were housed on shavings and feeding steamed hay.
After treatment, veterinarians performed follow-up overground endoscopy in three horses and repeat tracheal wash/BAL in eight horses; they also spoke with owners of 22 horses on the phone.
“Treatment was successful in 22 of the 25 cases,” ter Woort said. “These horses stopped coughing or making a respiratory noise and were performing up to expectation.”
On average, she said, treatment lasted three weeks, and some cases received repeat treatment.
She said treatment wasn’t successful in two horses with very chronic DDSP (three months or more before the first visit) and one in which DDSP developed following tie-back surgery.
“This study shows that, in this sport horse population, DDSP was associated with lower airway inflammation in a large proportion of cases and can be managed medically.”
If medical treatment fails, however, surgery is always an option, ter Woort said.
“But always make sure that medical treatment has really failed,” she said; for example, in horses with airway allergies, surgery won’t resolve their underlying condition alone—the environment must be changed and they might require medication, as well. “So, I just make sure that the medical treatment and environmental modifications have really been followed.”