Mud Fever is caused by a bacteria called Dermatophilus congolensis, which is found in the soil and on the skin of grazing animals. The bacteria sit around innocuously on normal skin but can invade damaged / vulnerable skin and then multiply causing an infection. Skin is damaged by repeatedly getting wet and dry or scratched / abraded by thistles or sand or aggressive grooming etc
Sores are usually found on the lower legs, especially at the back of the pastern. One or more legs may be affected.
Horses vary in the severity of signs seen, such as:-
- Matted areas of hair containing crusty scabs
- Reddened skin (if you clip hair away, much larger area affected than you first think)
- Small, circular, ulcerated, moist lesions some with scabs
- May be some ooze or discharge varying from orange watery goo to thick green/yellow pus – sometimes incredibly sticky and difficult to remove
- Scabs may remove hair in small clumps
- Deep cracks (often horizontal) in the skin
- Eventual hair loss leaving raw-looking areas which may bleed
- Sometimes legs are very swollen
- Some are extremely painful and others only slightly sore
- Possible lameness +/- heat
Pink skin under white hair (L) seems most susceptible but can spread to dark skin too (R).
Heels are the most common site for mud fever.
Rain scald is caused by the same bacteria as mud fever and develops for the same reasons. It is the name given to the condition when it occurs on the body.
Rain scald – lesions are typically seen on the neck, back, flanks and rump.
Keeping the skin clean and dry is the basis of treating the condition. This may only be achievable if the horse is removed from the wet and mud and kept stabled for some time. Treatment has to reach the causal organisms (bacteria) under the scabs, so these must be lifted and removed at the start.
- Softening the scabs to aid their removal is beneficial, e.g., cream may be applied and left to soak in for a few hours. Some of the tougher scabs may need soaking or poulticing first to soften them, before they can be peeled away.
- Once the scabs are softened the hair should be clipped away and then the area should be washed – using either a mild disinfectant such as dilute chlorhexidine (hibiscrub) or pov-iodine wash or even better a medicated shampoo such as Allermyl and then rinsed well. Make sure you clip enough away to show a halo of normal skin, which helps prevent spread under the hair.
- Drying the limb thoroughly is vital before applying any creams – it is important not to rub the skin and cause further trauma whilst drying, so dabbing with (paper) towel is a good option. Once dry, there are numerous creams, lotions and emollients that may help.
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 is 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. In general, they are of secondary importance to correct management. While most cases can be resolved, some have a tendency to recur. Management changes to help prevent any further problems are worth pursuing. It is sensible for all tack, grooming brushes, boots etc that have been in contact with infected skin to be disinfected.
Aggressive deep infection.
- 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
- Consider topical barrier creams (usually produced in an oily base) such as tea tree oil, sulphur, zinc & castor oil, aloe vera, honey with vitamin E, dermisol cream, filta-bac, udder cream or petroleum jelly. Use on clean, dry legs or underside of belly prior to turnout or exercise
- Try using breathable waterproof leg wraps for turnout eg Equiwraps
- Consider nutritional supplements for promoting a healthy skin, such as soya/cod liver oils, seaweed (not for pregnant mares), zinc (biometh Z), antioxidants, camomile or yarrow.
- Rotate paddocks to avoid poaching
- Avoid riding in abrasive surfaces sach as crag or sand if your horse is prone to skin problems
- Use electric fencing to block off muddy areas around gates
- Be vigilant. The sooner you spot the first tell-tale signs of mud fever, the quicker you can take action and so prevent a lengthy, and costly, recovery
- Accept that some horses will require constant treatment
- Dispose of hair or scabs removed from infected horses.
- Prevention techniques that work well for one horse may not work in another horse so it is a case of finding what suits your horse.