Insect bite hypersensitivity on horses to be studied

Researchers at Wageningen University and Utrecht University are starting a large-scale joint project on one of the most prevalent skin afflictions in horses and ponies: insect bite hypersensitivity (IBH). The study will involve both genetics and immunology, and the interaction between these fields, in order to develop diagnostics, intervention strategies and treatments for reducing the number of affected horses and ponies. The aim of this study is to increase knowledge about the immunological, epidemiological and genetic process of IBH by identifying genes and mechanisms responsible for the increased susceptibility to IBH. This knowledge can then be used to develop intervention strategies which focus on reducing the prevalence of IBH and improving the welfare of affected horses.

In 2006, more than 400,000 horses were kept in the Netherlands for recreation, sports and breeding. Approximately 10% to 15% of horses that are kept outdoors regularly suffer from IBH. This is an allergic reaction of the horse, which is found worldwide, to the bites of certain Culicoides species. The allergic reaction causes intense pruritus, which results in self-inflicted trauma. Symptoms are usually found along the horse's mane and tail. The welfare and commercial value of affected horses is seriously diminished. Moreover, severely affected horses are unsuitable for riding or showing because of extreme discomfort and disfiguration. The aetiology of IBH involves multiple factors, including environmental and genetic factors. The prevalence of IBH can be high in certain areas. Currently, no effective treatment or prevention methods are available.

Preliminary results show that the prevalence of IBH varies from 0% to 71.4% in different regions of the Netherlands. In addition to regional differences, large differences are also found between breeds: 8% in Shetland ponies and 18% in Friesian horses.

Four researchers will be working on this project during four consecutive years. This large-scale project will be financed by the Technology Foundation STW of the Netherlands Organisation for Scientific Research (NWO), Artu Biologicals, Vereniging Koepel Fokkerij and the two universities. Two groups from Wageningen University are involved in this project: the Animal Breeding and Genomics Centre (Van Arendonk), and Cell Biology and Immunology (Savelkoul). Both the Department of Equine Sciences (Sloet van Oldruitenborgh) and the Department of Infectious Diseases & Immunology (Willemse, Rutten) from Utrecht University are involved.