Equine dermatitis is commonly called mud fever. It affects many horses in New Zealand due to the wet winters and the plenitude of mud. White haired limbs with underlying pink skin are most commonly affected. Mud fever is often primarily due to a bacterial infection, though it can also be caused by fungal organisms. Signs of mud fever include loss of hair on areas of the legs, pink irritated skin, and crusting and matting of the hair (Figure 1).
Figure 1. Typical appearance of mud fever
Treatment of mud fever is a 4 step procedure.
- Clip the hair from the region involved. This will decrease the amount of moisture the hair is able to hold and therefore improve the limb’s ability to dry.
- Wash the affected area with an antibacterial scrub such as chlorhexidine. Malaseb© or an iodine scrub can also be used, though they tend to be more irritating than the chlorhexidine.
- Dry the area thoroughly. This is key to minimizing growth of fungi.
- Place a topical antibacterial ointment. In addition, an ointment containing an antiinflammatory medication such as a steroid and an anti-fungal may facilitate healing. Some products include Imflamol©, iodine spray, and Vet Associates Mud Fever Lotion. Place a bandage if the skin is very irritated, and maintain the horse in a dry area (a covered yard or box).
Skin on the limbs of horses is slow to heal. Have patience when treating your horse for mud fever. As long as gradual progress is seen, you are doing the right thing. If the skin refuses to heal, or the horse develops swelling in the limb or lameness, it is necessary to call out your veterinarian. They can do a skin scraping to determine the exact microbe that is causing the skin irritation and culture the skin to assure your topical antibiotic is appropriate.
In addition, there are some underlying disease processes, such as PPID or liver disease, that put a horse at increased risk of developing mud fever and may prevent or decrease healing. Your veterinarian can also assess your method of treatment to see if any changes can be made. Systemic antibiotics may be necessary if your horse has developed cellulitis, a deep infection of the skin that can be started from a simple case of mud fever.