Insect bite hypersensitivity (IBH) generally occurs during the summer months, from June – August, and is one of the most common skin diseases in horses.
Horses that suffer from this condition are allergic to the saliva of insects, which is unfortunate given the quantity of flies and other potential troublemakers (horse-flies, midges, gnats, mosquitos etc) that are permanent residents in stables, fields and grazing paddocks throughout the warmer stages of the year.
Insect bite allergies may present in a variety of ways, including hives, itchiness, hair loss, and dermatitis, or a combination of some or all of these symptoms. The time of year that these issues arise, as well as the clinical indicators themselves, are the most common means by which insect bite hypersensitivity is diagnosed. Note that intradermal allergy testing is required to diagnose this condition for definite.
The best means of treatment is aiding prevention, by way of avoidance or repellence of the insects. Pyrethrin insecticides are usually a key ingredient of any effective fly spray, which break down when exposed to sunlight, on account of the ultraviolet light. Prior to using these sprays, it is important to check the label of any pyrethrin fly spray to ensure that it contains a sunscreen to prolong activity and maximise effectiveness.
Midges are most prominent at dusk and dawn; therefore, it is a good idea to schedule turnout of susceptible animals around these problematic times. Fans in stables and stalls can assist in keeping midges away, as well as regular mucking out and changing of water sources, which can help to reduce breeding of small insects.
Early relief from itching and/or hives is key in preventing insect bites develop into something more problematic. Inflammation can be reduced by scaling back on corticosteroid. Unfortunately, it is worth noting that antihistamines on their own are ineffective in treating hypersensitivity to insect bites, in most cases.
Omega-3 fatty acid is found in good quality marine-derived fish oils, and have been proven effective in horses with allergies if taken consistently, over a prolonged period of time. It helps to reduce inflammation of the skin, while at the same time promoting healthy hair growth without the potential complications that corticosteroids can induce.
Insect bite hypersensitivity can be managed by using a combination of proven best practices; use of insect-repellents containing pyrethrin insecticides, the implementation of strategic turnout patterns, consistent administration of omega-3 fatty acids, and finally, some simple stable/stall maintenance tactics during peak midge season.