What is mud fever?

Mud fever is a bacterial skin infection affecting the lower legs caused by the bacteria dermatophilus congolensis. The bacteria are unable to enter normal skin; however if skin is weakened through prolonged wetting, or damaged by a cut, rub, or trauma, then the bacteria can enter and multiply, starting an infection. White skin tends to be more sensitive, so is easier for the bacteria to get in.

Standing in muddy, wet conditions will weaken horses’ skin and provide these bacteria with the five star accommodation and conditions that they need to survive and breed, which is why when mud fever starts it can quickly worsen.

Horses in Mud

What are the signs of mud fever?

Mud fever is usually easily recognised as hair becomes matted and contains oozing, crusty yellowy scabs, which when removed have moist lesions underneath. There may also be a thick, creamy, white or yellow discharge. Mud fever causes an acute inflammatory reaction, so the skin will be reddened and warm.

Mud fever affects just the lower limbs. Rain scald is caused by the same bacteria and the symptoms are very similar, however the back and flanks are affected rather than the legs.

How can mud fever be treated?

Mud fever bacteria live under the scabs, as they need warm, moist conditions to breed. This means that to treat mud fever we need to start by gently removing the scabs. This can either be done by soaking them off using warm water containing a dilute chlorhexidine based antibacterial skin cleanser or a product can be used that is designed for this purpose, such as Nettex Muddy Marvel De-Scab.

The legs then need to be dried, use paper towel to do this so that it can be thrown away and you won’t risk re-infecting your horse’s legs. An antibacterial formula can then be used to help get rid of the mud fever bacteria Nettex Muddy Marvel Disinfect is ideal. Your horse needs to be kept in clean, dry conditions and this process repeated daily until the mud fever has cleared up.

Mud fever bacteria can’t survive in clean, dry conditions, so with cleaning and a few days out of the wet the condition should quickly clear up. If mud fever is very severe or doesn’t resolve with these simple measures your vet should examine your horse.

How can you prevent mud fever?

Mud fever can be prevented by keeping your horse clean and dry and treating any cuts and grazes as soon as they occur. However, we don’t live in a perfect world, so most horses are exposed to muddy and wet conditions over winter.

The key to preventing mud fever is to prevent prolonged mud contact, minimise skin trauma and maintain healthy skin and a healthy immune system.

Preventing prolonged mud contact

Where horses are turned out in wet and muddy conditions paddock boots can be used to protect the legs from mud. However, they need careful attention to prevent rubbing and skin trauma. Instead a barrier cream can be used to help protect skin from mud. Nettex Muddy Marvel Barrier Cream also has antibacterial and moisturising properties to keep skin supple and in great condition.

The next generation of protection from mud are barrier sprays. These act in the same way as a barrier cream, but are easier to apply. Nettex Seven Day Mud Away prevents mud sticking to the coat allowing quick removal by simple brushing. Application is required only once a week and it provides an effective barrier against mud meaning less washing of legs in the winter and making management much simpler.

Maintaining Healthy Skin

Maintaining healthy skin and a healthy immune system will mean that your horse will be less likely to suffer from mud fever. Good general healthcare and ensuring that your horse has a balanced diet are essential. Feeding an oil that has high levels of essential fatty acids will improve skin and coat condition. Nettex Linseed Oil is ideal as it contains high levels of Omega-3 fatty acids which have been shown to benefit the skin.

What else can cause similar signs to mud fever?

There are other conditions that can mimic mud fever, so it is really important if your horse doesn’t respond to simple mud fever treatment to get your vet involved. Several conditions can cause the skin to become photosensitised and develop sunburn, which quickly becomes infected and looks exactly like mud fever.

Muddy Horse FeetShould I wash my horse’s muddy legs?

So what should you do when your horse comes in with their legs covered in mud? There is an argument that washing mud off simply makes the legs wetter and potentially compromises the skin and that leaving it in place may actually protect the skin.

However, the bacteria that cause mud fever (Dermatophilus congolensis) are present within the mud, so others take the view that washing mud off and drying the lower legs reduces the number of bacteria on the legs and limits the potential for mud to irritate the skin.

My personal belief is that there is no single solution that suits all horses as they are all individuals with different skin and coat thicknesses. This means that a little trial and error is required to work out the best way to manage your horse when conditions are muddy. Once you have established what works for your horse stick with it and don’t be swayed by fads or the opinions of others.

Why don’t wild horses get mud fever?

Wild horses are able to roam over vast areas. This means that in harsh winter weather they are able to seek out natural shelter and areas to rest that have free-draining dry soil.

This bears little resemblance to how most of us keep our horses today. Domesticated horses are usually kept in paddocks. Over the winter these quickly can become cut up, especially as most modern horses are shoed. High foot-fall areas will quickly become poached, such as gates and around water troughs. This means that our horses are not able to avoid mud and sodden conditions.

Native breeds have thick coats designed to protect the skin from adverse weather and mud. However these breeds are now a minority and today’s horses are predominantly bred for their athletic ability. This means they are usually fine skinned with thin coats that give little protection. These factors combine to make modern horses much more prone to mud fever than wild horses.

Other winter skin problems:

Rain scald

Rain scald is generally seen during the autumn and winter months and is avoidable with good management. It is caused by the same bacteria as mud fever, but affects skin of the back and flanks rather than the legs.

Rain scald is most common in unrugged horses kept in wet and muddy conditions with little shelter, where the coat is constantly wet. However, it can occur in rugged horses, if they get too warm and dirty rugs start to rub.

Rain scald can be identified as scabs, often with tufts of hair attached to them. The hair on the scabs often stands up and looks like paintbrush bristles.

If your horse has rain scald he should be brought into a stable and kept dry. The scabs need to be gently removed and the area cleaned, Nettex Muddy Marvel De-Scab is ideal for this purpose.

The skin should then be dried and a chlorhexidine based solution such as Muddy Marvel Disinfect applied. Severe cases may need veterinary treatment.

Feather mites

Heavily feathered breeds are prone to feather mites. Mites cause intense itchiness and irritation. Affected horses stamp their feet and will chew and rub their legs. They then develop sores and thickened skin which can become infected. Feather mites are frustrating to treat and reinfection is really common.

Keeping heavily feathered legs clipped will help prevent mites, but this is not useful advice if you want a traditional appearance. Washing heavily feathered horses legs in an anti-scurf shampoo, such as Nettex No Scurf Shampoo will get rid of dead skin cells and scurf which are a prime breeding grounds for mites. If you are concerned that your horse might have feather mites discuss the treatment options with your own vet.

Nettex Feather Mite Powder is a completely natural mite control powder and breaks down the waxy coat of mites causing them to dehydrate and die. It is most effective when used year round as an aid to control feather mites.

Written by

Dr Becky Lees BVSc Cert AVP (EM) MRCVS

Veterinary Technical Manager

Part of the Nettex Equine Guides