A new study suggests that magnetic resonance imaging (MRI) can help identify those horses most likely to benefit from neurectomy---the severing or removal of nerves---to control hoof pain.
Because it doesn’t always provide long-lasting relief and can lead to further damage to critical hoof structures, neurectomy is a somewhat controversial procedure. “In some horse communities and certain areas, neurectomies have a bad reputation, but the surgical procedure is actually not bad at all if patient selection and postoperative care is adequate,” says Santiago Gutierrez Nibeyro, DVM, of the University of Illinois. “Neurectomies can be detrimental in some horses because they don’t feel their feet and can overload an already damaged and biomechanically weaker structure of the foot. But the procedure is a reasonable and suitable option in the face of a poor response to conservative therapy, such as local injections or nonsteroidal anti-inflammatory medications.”
To help determine which horses are the best candidates for neurectomies, Gutierrez and fellow researchers examined the records of 50 horses referred to six different equine clinics because of heel pain. Each horse underwent an MRI as part of the diagnostic process, had a neurectomy as treatment and was available for follow-up for at least 15 months after the procedure.
The aggregated data showed that the neurectomy’s effectiveness in treating lameness depended on its underlying cause. “Horses with lesions of the navicular bone remained sound for approximately 30 to 36 months after the procedure,” says Gutierrez. Those with fraying of the deep digital flexor tendon stayed sound approximately 24 months. Horses with a “core” or “linear” lesion of the deep flexor tendon, however, were sound for only about 12 months after neurectomy.“
These are tears of the digital portion of the deep digital flexor tendon that involve the substance of the tendon,” explains Gutierrez. “In other words, there is fiber rupture of a large proportion of the substance of the tendon. The lesions can be round (core) and located in the center of the tendon or can be straight (linear) and dissect thought the tendon.”
Gutierrez says horses with core or linear lesions may not stay sound as long because the pre-existing injury of the deep digital flexor tendon worsens over time or extends close to a location in the foot that has not been desensitized. He says that he recommends an MRI scan before performing a neurectomy to rule out horses with lesions of the deep digital flexor tendon. “In these cases,” he adds, “alternative surgical procedures and the use of intralesional biologic therapies might be more effective and less risky than a neurectomy.”
Reference: “Outcome of palmar/plantar digital neurectomy in horses with foot pain evaluated with magnetic resonance imaging: 50 cases (2005-2011),” Equine Veterinary Journal, March 2014
This article first appeared in EQUUS issue #442.