URTICARIA OR HIVES IN HORSES

Urticaria or Hives Urticaria (hives) is one of the most common skin problems faced by horses.

It is the result of a hypersensitivity (allergic) reaction and identified as multiple raised, oedematous(fluidy), flat topped swellings, which often will dent or ‘pit’ when pressure is applied to them.

Although occasionally itchy they usually cause no discomfort to the horse. Any age or type of horse can be affected, though thoroughbreds are probably over-represented.

CAUSES

• Food
• medication
• insect bites
• stings
• pollens
• mould 
• fungal spores
• extreme temperatures
• stress and many others

TREATMENT

• The majority of sudden onset cases of urticaria will spontaneously resolve in 24-48 hours, so if the horse is not otherwise affected it may be best to hold off any treatment, initially.
• However, if the horse shows any signs of discomfort or distress then treatment should be sought immediately.
• The most common and usually the most effective treatment is an intravenous injection of corticosteroid, which blocks the production of inflammatory substances which are what cause the wheals to form.
• Steroids need to be used with care, particularly in horses at risk of other conditions, such as laminitis and in competition horses, where it is a restricted substance.
• Vigorous exercise may help to reduce the reaction.
• Antigen desensitisation, or ‘self-vaccination’, is a costly process with very variable results. There is little scientific evidence for its use.
• Anti-histamines are expensive and generally produce only poor results. If all else fails a complete change of environment and placing the horse on an exclusion diet of hay and grass only,may be the solution.

Reference

http://www.minstervets.co.uk/uploads/Files/Urticaria%20or%20Hives.pdf