As the long and very likely wet winter approaches, we are starting to see more cases of Mud Fever and Rain Scald.

Also known as pastern dermatitis, ‘cracked heels’ and ‘greasy heels’; mud fever is a common condition of the lower limbs, where the skin becomes inflamed and scabby with oozing serum. The coronet, pastern and heels of the foot may also become cracked. In severe cases the leg may swell and the horse may develop lameness. The problem is caused by bacteria (which are usually dormant in skin), becoming active when the skin barrier is injured or damaged (often by a prolonged wetting but also via cuts/wounds). The infection enters the horse’s body through the broken skin, and multiplies in the damp, warm skin layers, starting an active infection.

The idea that mud fever is always caused by a single bacterium called Dermatophilus congolensis, is no longer true. Although one species is often the dominant cause, most infections are caused by mixtures of different bacterial species including Staphylococcal or Streptococcal strains. There may also be fungal organisms present.

Horses with particularly hairy feathers, white legs or pink skin are more prone to mud fever. The condition can also affect the upper body and is usually referred to a rain scald or rain rot.

What are the Clinical Signs of Mud Fever?

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 – in severe cases the skin at the back of the leg may split open, producing the horizontal fissures that are characteristic of cracked heels

• Eventual hair loss leaving raw-looking, inflamed skin underneath

• When found on the front legs it can be mistaken for over-reach injuries

• Heat, swelling and pain on pressure or flexion of limb

• Possible lameness

• If severely affected, lethargy, depression and loss of appetite

How Can I Prevent My Horse From Getting Mud Fever?

Preventing your horse from infection with mud fever can be challenging, but twice-daily checks can ensure you are one step ahead. Prevention is definitely the name of the game!

• Some horses are more susceptible to mud fever than others, and wet, muddy conditions only exacerbate the problem.
• Mud fever particularly affects horses that live out all year round; if your horse is turned out 24 hours a day you should make a point of bringing him in every now and then to let his legs dry out completely and brush the mud off.
• Once your horse's legs are clean and dry application of an oil-based cream can be used as a barrier against the moist conditions; Vaseline is the ideal cream for this purpose, but you could also use vegetable oil or baby oil.
• If you are going to use baby oil, make sure you test it on a small area of your horse's skin to make sure he isn't allergic to it - it has been known to cause allergy in some horses.

Mud fever can be difficult to prevent so when checking your horse's legs keep an eye out for any signs of the condition. If at any time you do notice soreness, weeping or scabs speak to one of the equine vets here at St Boniface so that an appropriate treatment can d be initiated as soon as possible to prevent the condition worsening.

How Can I Treat My Horse For Mud Fever?

Treatment of mud fever must set out to achieve two main objectives: to remove the cause, and to treat the skin damage. Early veterinary attention will help considerably.

Antibiotics may be needed if it is infectious but a common mistake is to carry out repeated heavy washing of the skin. One of the best principles that can be applied is to render the skin inhospitable to the causative bacteria - this may mean close clipping (even if it's a feathered horse) and a single careful wash with a suitably prescribed antiseptic solution.

It is very important in all these case to use warm water when washing and rinsing. The worst thing that one can do is to macerate the skin still further by leaving it wet. Blotting dry (rather than rubbing with a towel) and then maintaining a dry skin are the most helpful measures.

In some cases removal of the scabs and washing the affected area can be too painful to be safely carried out. If your horse is becoming distressed he/she may need sedation from the vet to allow a thorough clean of the legs. If you have any concerns please speak to one of the equine vets at St Boniface.

By following these important stages you can ensure a successful outcome:

• While being treated for mud fever your horse should be stabled to prevent him from coming into further contact with the wet or mud. Make sure the bedding in the stable is dry, clean and non-irritant.
• All the hair around the affected area should be clipped away - be careful not to break the skin when clipping the affected areas. The legs should be thoroughly cleaned with an antiseptic this will soften any scabs which need to be removed.
• All the scabs must be removed so that the treatment used can reach the affected skin - removing the scabs a little at a time will cause less trauma to the underlying skin.
• The legs should then be thoroughly and gently dried.
• The infected skin should be treated with a cream/solution formulated to attack the bacteria that causes mud fever. In severe cases antibiotic treatment may be needed, if this is the case you should call your vet.
• Once the mud fever has been treated and the infection has been cleared, the affected area must continue to be protected while new skin and hair grows. This process may take a while and the skin may remain tender during this period, it is advisable to apply a soothing cream.

Will the Problem Come Back Once it has Been Treated?

If your horse is prone to mud fever it is likely that it will recur if your horse is exposed to wet and muddy conditions again. Ideally you should clean your horse's legs and allow them to dry out on a daily basis to prevent it from coming back.