Mud fever, also known as pastern dermatitis, is an infection in the skin, normally around the pastern area. This usually starts with a small crack or abrasion that becomes infected by bacteria, fungi, and occasionally mites. It primarily affects light skinned areas on the horse’s legs. It develops most often during the winter months when continuous exposure to moisture softens the skin and allows bacteria to invade. It can also occur in summer when dry cracks in the skin allow for infection. Painful scabs or “crusts” develop, which leave raw areas when removed.
Treatment is notoriously difficult, but most horses respond to aggressive therapy. This includes:
- Clipping the affected region
- Regular cleaning with an antibacterial shampoo such as Vetadine, Hebiscrub (chlorhexidine), or Maleseb
- Removal of scabs
- Application of antibacterial ointment with or without a bandage.
Removing the scabs is the key to successful treatment, as these scabs protect the organisms that cause the disease.
The horse may need to be sedated and the hair clipped to aid in cleaning and removal of these scabs. Stubborn scabs may need to be soaked with warm water or bandaged with an antibacterial ointment to soften them and allow gentle removal. Once the leg has been thoroughly cleaned with an antibacterial shampoo and as many scabs removed as possible, the affected areas should be dried thoroughly, followed by application of an antibacterial ointment. There are several types of antibacterial ointments which can be used on mud fever. The more potent and effective ointments contain antibiotics and require veterinary prescription.
Controlling mud fever may be a winter-long activity in some horses, but it is important not to let it get out of control as mud fever can cause significant pain and swelling in affected limbs. This infection can lead to cellulitis, infection of subcutaneous tissues (below the superficial layer of skin,) which requires systemic antibiotics and veterinary attention. Generally horses with mud fever are not lame and if they are, they need to be seen by a veterinarian.