The results of a new study conducted by researchers at the University of Pennsylvania's School of Veterinary Medicine (PennVet) New Bolton Center suggest owners and their veterinarians should consider a modified laryngoplasty to correct roaring in affected horses.
In a roarer, the muscles that open and close the left side of the larynx as the horse breathes are atrophied, causing the arytenoid cartilage (which closes over the trachea when a horse swallows) to droop into the left side of the airway. This effectively blocks the flow of air into the lungs.
"The surgery of choice for roarers is laryngoplasty, which involves placing sutures between two of the throat cartilages to pull the affected arytenoid cartilage open," explained Eric Parente, DVM, Dipl. ACVS, from PennVet's Department of Clinical Studies.
The goal of any laryngoplasty is to maintain a large opening during exercise for air to travel unabated through the larynx to deliver as much oxygen to the horse's lungs (and, thus, working muscles) as possible--a feat that is only successful in approximately 45-70% of treated horses via the traditional route.
"Due to the less-than-ideal success rate of the traditional procedure, we devised a 'modified' laryngoplasty technique that would hopefully achieve a more positive successful outcome," Parente said. "The modified approach involves placing the sutures differently to minimize interference and loosening and debriding the joint between the two cartilages to enable fusion of the joint and long-term stability of the opening."
Parente and colleagues performed the modified laryngoplasty surgery in 70 Thoroughbreds and subsequently compared the racing data from those treated horses with 210 untreated nonroaring Thoroughbreds.
"We hypothesized that using quarterly earnings would be a better way to assess a racehorse's performance following the laryngoplasty surgery (than previous studies on roarers)," said Parente.
Key findings of the study were:
- Not surprisingly, in the last race before surgery, horses performed significantly worse than the untreated horses, with 44% of the roarers finishing last or next to last;
- After the first quarter (when the horses were rested), there was no difference in race starts or dollars earned between the two groups of horses.
"These data show that treated horses went on to race for at least as many quarters as the untreated controls, indicating that the modified laryngoplasty surgical procedure is effective," summarized Parente.
Other surgeons have adopted the modified technique, and its cost is estimated to be the same as the traditional technique. As for Parente: "I am continuing to look for even better techniques."
The study, "Using quarterly earnings to assess racing performance in 70 Thoroughbreds after modified laryngoplasty for treatment of recurrent laryngeal neuropathy," will appear in an upcoming edition of Veterinary Surgery. The abstract can be viewed on PubMed.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.