Cranial Electrotherapy Stimulation for Treating Stress-related Disorders in Horses

The Hungarian National Police Force comprises of a section on horseback. Their work involves having to patrol varied terrain, as well as providing riot control at football matches. They also carry out the tasks of the Hungarian Subsidiary National Horse Ceremonial Unit. Changeable conditions and competence in a wide range of diverse tasks, see these horses endure much higher stress levels than horses for recreational use only. Recent studies describe an effective and drug-free alternative in the treatment of human anxiety disorders, called cranial electrotherapy stimulation or CES. CES is a non-invasive therapeutic device that has recently been used in the treatment of human depression, anxiety and sleeping disorders. Such cranial stimulator exists also for horses (Happy Halter, Fisher Wallace Laboratories). Twelve Hungarian Warmblood gelding police horses with a mean±SD age 10.3±3.8 years were selected randomly for the study, out of them six horses received Happy Halter treatment and six horses received placebo treatment. The Happy Halter device was placed on the head of the placebo horses the same way as on the treated horses, but no stimulation was given. The Happy Halter treatment lasted for 20 minutes with level 1 intensity (weakest intensity, the suggested intensity level for humans). Saliva samples were collected with cotton-based swabs and cortisol concentration was determined by an enzyme-immunoassay technique. Beat-to-beat (R-R) intervals were recorded by Polar® Equine heart rate monitor. Behaviour reactions were judged visually, and fearful or painful reactions of the horses were noted. For statistical analysis we have divided the time periods into two categories, before treatment (time periods 1-3) and after treatment. Before or after the Happy Halter treatment no differences were found between placebo and treated horses regarding HR or salivary cortisol concentration. During the first treatment a significant increase in parasympathetic tone (HF) could be observed in the treated group, but not in the placebo group. The lower vagal tone (HF, parasympathetic tone) of the more anxious horses implies that these horses have a lower capability to react as competently to an external stimulus as a normal horse who possess a higher vagal tone. A higher vagal tone provides greater flexibility when faced with a stressor. Regarding behavioural changes in relation to the application of the Happy Halter itself, there was little or no behaviour reaction to the device. Although it must have been strange to the horses (as HR increased a bit in both placebo and treated groups), but probably not painful. Our preliminary results suggest that Cranial Electrotherapy Stimulation for treating stress-related disorders in horses may be promising. Further studies involving more horses with extreme anxiety levels and perhaps treatment with greater intension and for longer period may be needed to support or reject the effectiveness of Happy Halter treatment in horse