While headshaking can be a purely behavioral problem in many horses, it can also result from severe facial pain or irritation, possibly due to a nerve disorder. Some headshakers with nerve disorders are euthanized while others undergo a surgical procedure called caudal compression of the infraorbital nerve to relieve the pain. The procedure involves placing a tiny platinum coil into the infraorbital canal to put pressure on the infraorbital nerve. In theory, the coil's continuous feedback should stop nerve firing, thereby corroborating the nerve as a source of facial pain or irritation.
A recent study suggests this surgery could be a viable option with a long-term success rate of nearly 50%; however, researchers are continually working to find a more effective treatment method for headshaking.
To evaluate the long-term success rate of caudal compression of the infraorbital nerve, Veronica Roberts, MA, VetMB MA, Dipl. ECEIM, MRCVS, a clinical fellow in equine medicine at the University of Bristol, England, and her team reviewed clinical records of 58 horses that underwent this surgery between June 2004 and January 2011 at the University of Liverpool or the Royal Veterinary College in England or at the Strömsholm Specialist Animal Hospital in Sweden. The horses, aged 1 to 17 years, were used for general riding, show jumping, eventing, or dressage and had a history of headshaking.
Key findings from the study included:
- Surgery was initially considered a success in 35 of 57 (63%) horses, but headshaking recurred between nine and 30 months later in nine horses;
- Practitioners repeated the surgery in 10 horses;
- The overall success rate at an average follow-up time of 18 months, considering only the response to the last surgery performed, was 49%;
- Owners reported nose rubbing in 30 horses at long-term follow up after surgery;
- Nose rubbing resolved in all but four horses that were subsequently euthanized.
The team concluded that the "caudal compression (procedure) offers the best prognosis for a successful outcome ... for horses in which the only alternative is euthanasia."
"The surgical treatment of the disease clearly requires refinement and improvement," said Roberts. She noted, however, that even in human facial pain cases, "there is no universally effective, minimally invasive surgical treatment that immediately and completely relieves signs with consistent long-term results and without side effects."
Since the study's completion, Roberts has received a grant from the British Neuropathologic Society to investigate possible focal demyelination of the nerve as a cause. She asks that anyone considering euthanizing a horse due to headshaking to contact her for possible inclusion in her work to find a more effective treatment.
The study, "Caudal anaesthesia of the infraorbital nerve for diagnosis of idiopathic headshaking and caudal compression of the infraorbital nerve for its treatment, in 58 horses," will appear in an upcoming issue of the Equine Veterinary Journal. The abstract can be viewed online.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.