Date Published: May 26, 2006
Publisher: BioMed Central
Author(s): Sigríður Björnsdóttir, Jakobína Sigvaldadóttir, Hans Broström, Birgitte Langvad, Ágúst Sigurðsson.
A cross sectional study was designed to estimate the prevalence of summer eczema (a chronic, recurrent seasonal dermatitis) in exported Icelandic horses and the influence of environmental and genetic factors on the development of the disease.
Summer eczema (SE) also known as equine insect bite hypersensitivity or sweet itch, is a chronic, recurrent seasonal dermatitis of horses caused by an allergic reaction to the bite of Culicoides ssp midges [1-4]. The symptoms include intense pruritus, self-excoriation resulting in open wounds and secondary infections and are usually localized to the mane, tail and withers . Most breeds of horses can be affected although the prevalence seems to vary considerably between countries and different regions within countries [5-10].
In total 330 horses were examined for summer eczema, 170 in Germany, 82 in Denmark and 75 in Sweden. The age of the horses ranged from 1 to 25 years with the mean of 10.3 years. The distribution of gender was 58% mares, 31% geldings and 11% stallions. The age at export was known for 262 of the horses (79.4%) and ranged from few months to 16 years. The mean age at export was 3.1 years. Time since export was known for 312 of the horses (94.5%) ranging from few months to 22 years with the mean of 4.7 years.
At the time of the examination a central database did not exist for Icelandic horses in Europe prohibiting selection of a random material from the population. The central database  introduced in 2000 has improved the availability of information about the population. The wide distribution of exported Icelandic horses in Europe, where they are kept in different environments and where the management is variable, make a complete epidemiological study difficult to perform. The owners are, however, well aware about the disease and were willing to participate with their horses in the survey. Emphasis was made on visiting large horse farms where all horses fulfilling the criteria were examined. On these farms, horses were kept from many owners who were not all able to be there personally at the time of the examination. This is the main reason for some missing data of the questionnaire.