Report of the 3rd Havemeyer workshop on allergic diseases of the Horse, Hólar, Iceland, June 2007

Abstract

Allergic diseases occur in most mammals, although some species such as humans, dogs and horses seem to be more prone to develop allergies than others. In horses, insect bite hypersensitivity (IBH), an allergic dermatitis caused by bites of midges, and recurrent airway obstruction (RAO), a hyperreactivity to stable born dust and allergens, are the two most prevalent allergic diseases. Allergic diseases involve the interaction of three major factors: (i) genetic constitution, (ii) exposure to allergens, and (iii) a dysregulation of the immune response determined by (i) and (ii). However, other environmental factors such as infectious diseases, contact with endotoxin and degree of infestation with endoparasites have been shown to influence the prevalence of allergic diseases in humans. How these factors may impact upon allergic disease in the horse is unknown at this time. The 3rd workshop on Allergic Diseases of the Horse, with major sponsorship from the Havemeyer Foundation, was held in Hólar, Iceland, in June 2007 and focussed on immunological and genetic aspects of IBH and RAO. This particular venue was chosen because of the prevalence of IBH in exported Icelandic horses. The incidence of IBH is significantly different between Icelandic horses born in Europe or North America and those born in Iceland and exported as adults. Although the genetic factors and allergens are the same, exported adult horses show a greater incidence of IBH. This suggests that environmental or epigenetic factors may contribute to this response. This report summarizes the present state of knowledge and summarizes important issues discussed at the workshop.

Multiple Hypersensitivities Including Recurrent Airway Obstruction, Insect Bite Hypersensitivity, and Urticaria in 2 Warmblood Horse Populations

“…Hypersensitivity disorders are important in horses, with recurrent airway obstruction (RAO), insect bite hypersensitivity (IBH), and urticaria (URT) among the most frequently observed 1, 2, 3, 4, 5, 6. In other species, including humans, dogs, and cats, a combined occurrence of multiple hypersensitivities (MHS) affecting different organ systems has been described.…”

Time-dependent changes of cytokines mRNA in bronchoalveolar lavage fluid from symptomatic Recurrent Airway Obstruction-affected horses

“…The absence of research standardization was correctly pointed out at the 3 rd Havemeyer workshop on allergic diseases where it was reported that "... no accepted recommendations exist for standardized exposure protocols and sampling time in experimental studies of RAO...", making comparison between studies difficult (Marti et al 2007).…”

“…Analogously, to date, no accepted recommendations exist for standardized exposure protocols and sampling times in experimental studies of RAO (Marti et al 2007).…”

Detection of reaginic antibodies against Faenia rectivirgula from the serum of horses affected with Recurrent Airway Obstruction by an in vitro bioassay

“…However, although the immunological aspects of RAO have been extensively studied, the precise sequence of events is still not well understood. Moreover, the involvement of an IgE-mediated mechanism in the pathogenesis of RAO-affected horses remains unclear and is still controversial (Marti et al 2008;Wagner 2009). Wagner (2009) suggested that more recent studies did not confirm an IgE-mediated pathogenesis of RAO.…”

“…However, the role of IgE-mediated reactions in RAO remains unclear (Marti et al 2008;Tahon et al 2009;Wagner 2009). Today, various techniques are available to detect soluble IgE and the sensitization of mast cell or basophils with IgE horses (Wagner 2009).…”