Dr. Brett Woodie, a board certified surgeon and partner at Rood & Riddle Equine Hospital, answers questions about “roarers”—horses with an upper-airway condition that, in serious cases, can adversely affect an equine’s ability to breathe properly during exertion.
A large focus of Dr. Woodie’s practice is devoted to helping horses with this condition. He was a member of the Cornell University surgical team that developed a surgical procedure (the Tie-forward) to correct dorsal displacement of the soft palate. In addition, he was instrumental in developing the Cornell Collar, a patented device that offers a surgical alternative by providing throat support to hold the larynx in proper position. The device fits on the horse’s head like a bridle.
Since joining Rood & Riddle in 2003, Dr. Woodie has concentrated his practice on airway issues. Here, he offers some insight into the medical condition commonly referred to as roaring.
Q: What are some of the surgical and nonsurgical methods of treating this breathing problem?
First, “roarer” is the common name used for a horse that has Grade IV left laryngeal hemiplegia (paralyzed arytenoid). The most common surgical treatment for this is a laryngoplasty (tie-back) and ventriculocordecotomy (removal of one or both vocal cords). In certain cases only a ventriculocordectomy is performed. Another procedure is a neuromuscular pedicle graft. This procedure involves transplanting a nerve (1st cervical nerve) from the area into the muscle (cricoarytenoideus dorsalis muscle) that has lost nerve function.
Q: I understand there are advances in surgical treatments. How is it done, and is there any new, promising research in this area?
One area of research that is promising is using a laryngeal neuroprosthesis (pacemaker) to stimulate the cricoarytenoideus dorsalis muscle to contract and open the airway.
*Research presented at the 2009 World Equine Veterinary Association by the College of Veterinary Medicine, Cornell University, indicated early, positive results in electrical stimulation in experiments done on horses. Researchers reported that when a pacing electrode was placed on the recurrent laryngeal nerve, stimulation resulted in full arytenoid cartilage abduction. And constant stimulation of this nerve for one hour led to full abduction without evidence of fatigue, the study reported.
Q: When and how is it determined that a horse’s roaring issue makes him or her unsuitable for riding?
Laryngeal hemiplegia causes an obstruction of airflow into the trachea. The level of exertion that is required of the horse is a major determinant of how much the horse will be compromised. As long as the horse is able to perform up to expectations and/or is not exercise intolerant, then he or she can still be used for riding.