The signs of mud fever are fairly classic and easy to recognise, with the distribution of the lesions reflecting the areas that have been subjected to continued wetting and trauma.
- Matted areas of hair containing crusty scabs
- Small, circular, ulcerated, moist lesions beneath scabs
- Thick, creamy, white, yellow or greenish discharge (containing the causal organism) between the skin and overlying scab
- Removed scab typically has a concave underside with the hair roots protruding
- Deep fissures in the skin
- Eventual hair loss leaving raw-looking, inflamed skin underneath
- Heat, swelling and pain on pressure or flexion of limb
- Possible lameness
- If severely affected, lethargy, depression and loss of appetite
Mud fever treatment
Keeping the skin clean and dry is the basis of treating the condition. This may only be possible if the horse is removed from the wet and mud and kept stabled for some time.
More specific treatment has to penetrate the causal organisms under the scabs, so these must be lifted and removed at the start. The animal will often need to be sedated for this, as it can be very painful. Some of the tougher scabs may need soaking or poulticing first to soften them, before they can be peeled away.
Once the area is clipped it should be washed — using either a mild disinfectant such as chiorhexidine, iodine wash or surgical scrub, or another a medicated shampoo — and then rinsed well. Drying the limb thoroughly is vital — a hairdryer is an excellent way of doing this.
Once dry, there are numerous creams, lotions and emollients that may help. Zinc, castor oil, lead acetate and various commercial anti-inflammatory ointments can all play a part, but only if the skin is dry underneath.
Likewise, bandaging an affected limb can be a good way of keeping it clean and dry, but only if the skin has been properly dealt with beforehand, and the correct bandaging technique is used. Bandaging that’s too tight or has moisture trapped underneath can allow an infection to flare up again.
This whole process may need to be repeated several times, and in bad cases a full recovery can take many weeks.
The use of antibiotics and anti-inflammatories will depend on the individual case. But, in general, they are of secondary importance to correct management.
While most cases can be resolved, some chronic epidermal scarring and weakening may be left, contributing to a tendency to re-infection. Management changes to help prevent any further problems are worth pursuing.
In problem cases your vet might take a blood sample, to check liver function if the dermatitis is limited to white areas of skin only.
Preventing mud fever
- Ensure bedding is clean, dry and non-irritant at all times
- Avoid over-washing and/or too vigorous grooming
- If bandaging, ensure limbs are clean and dry first
- Periodically disinfect all equipment, gear and stable surfaces, as they could harbour dermatophilus spores
- Consider topical barrier creams (usually produced in an oily base) such as tea tree oil, sulphur, MSM, aloe vera, honey with vitamin E, calendula and hypericum, goose grease and petroleum jelly. Use on clean, dry legs or underside of belly prior to turnout or exercise
- Try using waterproof leg wraps for turnout
- Consider nutritional supplements for promoting a healthy skin, such as soya/cod liver oils, seaweed (not for pregnant mares), antioxidants, herbs and essential oils such as lavender, camomile and yarrow
- Rotate paddocks to avoid poaching
- Use electric fencing to block off muddy areas around gates
- Be vigilant. The sooner you spot the first telltale signs of mud fever, the quicker you can take action and so prevent a lengthy, and costly, recovery
This feature was first published in Horse & Hound (8 December, ’05)