• Trigeminal mediated headshaking is an idiopathic facial pain syndrome in equids.
• The condition carries a poor prognosis with medical therapy having limited success.
• PENS therapy offers an alternative and successful therapy for the treatment of trigeminal mediated headshaking.
• PENS is a minimally invasive neuromodulation therapy that has applications in the human field for neuropathic pain.

Uses

• Sole use for the treatment of trigeminal mediated headshaking Behavior: headshaking and no other conditions.

Advantages

• Better success rate than the majority of other medical treatments.
• Intermittent treatment required rather than continuous medication.
• Tolerated well with most horses.

Disadvantages

• Incomplete understanding of the etiopathogenesis and therefore treatment success can be limited.
• Lack of response following treatment in a number of cases.
• Complication rate of 8.8%, most commonly a transient neuritis usually resolving in 3 days.

Technical problems

• Relatively simple procedure to undertake once fully trained but it is essential to rule out all non-trigeminal mediated reasons for headshaking.

Alternative techniques

• Nose nets (70% improvement in about 30% of cases).
• Medical therapy (gabapentin, carbamazepine, cyproheptadine Cyproheptadine hydrochloride).
• Electroacupuncture Acupuncture: overview.
• Platinum coil placement in the infraorbital canal (concerns about adverse effects leading to euthanasia Euthanasia).

Time required

Preparation

• 15-30 min.

Procedure

• 60 min.

Decision taking

Criteria for choosing test

• The horse should be diagnosed as a trigeminal mediated headshaker based on exclusion of other causes of headshaking.
• Horses should show stereotypical signs of headshaking (vertical uncontrolled head tick, rubbing of nose on the ground, etc).
• A thorough clinical examination should take place prior to administering PENS therapy including upper airway endoscopy Respiratory: endoscopy, ophthalmological examination Eye: examination – direct ophthalmoscopy, exercise testing diagnostic local anesthesia performed bilaterally at the caudal aspect of the infraorbital canal Infraorbital nerve: perineural anesthesia and, ideally, a head CT Computed tomography. Without these, an underlying pathology may be missed resulting in unsuccessful treatment.

Risk assessment

• Horses should be placed in stocks for the procedure and adequately sedated as some horses can violently react at the beginning of therapy. The stocks should not be bolted shut to allow rapid exit from the stocks if required.