Mud fever is not one condition but a collection of clinical signs associated with a number of different causes. Particularly evident during wet winter months, mud fever is also known as pastern dermatitis,dew poisoning, greasy heel or in the USA as scratches. Although very common mud fever is not limited to horse’s legs being stood in muddy ground it appears in various forms; for example on a horse’s back it is known as Rain Scald.
There are many factors which cause the condition:
• Genetics – white skin and feathers can cause horses to be more predisposed to irritation.
• Environmental conditions anything that irritates softens or breaks skin, such as standing in wet muddy ground, can allow bacteria to invade and cause infection.
• Physical and chemical irritants – allergies, insect bites and rubs from dirty tack and boots also allow bacteria to invade.
• Other infections – these can damage the skin and allow secondary infection to occur.
Bacteria in the environment, and other pathogens such as Dermatophilus Congolensis living in the mud, invade the skin’s weakened defences causing irritation and inflammation which in turn causes the scabby or exudative lesions that lead to soreness.
Although minor complaints can be treated, the immediate removal from the wet and muddy environment is essential. If excessive heat and swelling are detected veterinary attention must be sought.