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

The research article is about a workshop that focussed on studying the genetic and immunological aspects of two common allergic diseases in horses, Insect Bite Hypersensitivity (IBH) and Recurrent Airway Obstruction (RAO), and the factors affecting their prevalence.

Overview of the Workshop

• The 3rd Havemeyer workshop on allergic diseases was held in Hólar, Iceland, in 2007 with the help of the Havemeyer Foundation.
• The purpose of the meeting was to explore the genetic and immunological factors of the two most common allergic diseases in horses, Insect Bite Hypersensitivity (IBH) and Recurrent Airway Obstruction (RAO).

Insect Bite Hypersensitivity and Recurrent Airway Obstruction

• IBH is a type of allergic dermatitis in horses caused by midge bites, and RAO is an extreme reaction to stable dust and allergens.
• Allergic diseases such as these develop as a result of interplay between three primary elements: the genetic makeup of the individual, exposure to allergens, and dysregulation of the immune response, which is determined by the first two factors.

Additional Contributing Factors

• Aside from genetic constitution and allergen exposure, other environmental factors such as infectious diseases, exposure to endotoxins, and the level of endoparasitic infestation could also play a role in the prevalence of these diseases.
• The impact of these additional factors on the prevalence of allergies in horses is still unknown and required further investigation.

Significance of Study Location

• The workshop was hosted in Hólar, Iceland, due to the high incidence of IBH found in exported Icelandic horses.
• The frequency of the disease differed significantly between Icelandic horses born in Europe or North America and those born and exported as adults from Iceland.
• Even though genetic factors and allergens remained constant, exported adult horses showed a higher degree of IBH incidence, hinting towards environmental or epigenetic factors contributing to this reaction.

Present State of Knowledge

• This research summarizes the current understanding of the allergic diseases in horses and highlights the crucial issues discussed during the workshop.
• The findings of the research shed light on the importance of genetic, immunological, environmental and possibly epigenetic factors in the prevalence of common allergic diseases in horses.