Mud Fever – All you need to know!

Mud Fever – All you need to know!

By Dr Jim Rawlinson BVMS MBA MRCVS

What is mud fever?

Mud fever, or ‘cracked heels’ is a common term for a bacterial infection also known as pastern dermatitis. It is most commonly seen on the pasterns and is a condition that causes scabs, irritation, sores and in more severe cases heat, swelling and lameness. As the name suggests, mud fever is typically seen in winter, in wet and muddy conditions.

What causes mud fever?

Mud fever is caused by a combination of two factors – damage to the skin surface and bacterial infection.

The skin is a clever and effective barrier protecting the body from the outside world. In healthy horses it is perfectly normal for numerous different types of bacteria and microorganisms to live on the skin without causing any harm. However, when the skin is damaged, bacteria can enter and cause an infection. The most common type of bacteria found to cause mud fever is Dermatophilus congolensis, although other bacterial species can also contribute.

What causes the skin to be damaged?

The wet muddy conditions we tend to see throughout winter can play havoc with horse’s lower legs. The prolonged cold and wet can soften the skin, leaving it susceptible to abrasions from mud. Bacteria can enter the skin through these tiny rubs and infection can take hold.

Interestingly, there is an extra element that predisposes horses to suffering from mud fever, and that is the constant wet-dry cycle. Many horses can have muddy legs for the entirety of winter and don’t seem to have an issue with mud fever. But those who have their legs washed repeatedly can seem to struggle. It is thought that the wetting and chilling from cold water, coupled with inadequate drying can leave skin more susceptible to bacterial infections.

What does mud fever look like?

Mud fever can range in severity, but all cases have scabs, most commonly on the pastern. However, scabs can extend to the fetlock and in severe cases, the cannons. Along with scabs there is often oozing, heat, matted hair, hair loss, crusting, swelling and heat. Horses who are several affected can be lame.

How to treat mud fever

The primary objective of treating mud fever is to remove the scabs. The bacteria are thought to live in the scabs, so removing them will remove the bacteria. Also, Dermatophilus congolensis is an anaerobic bacteria, meaning it cannot survive in the presence of oxygen. Removing scabs exposes the affected area to oxygen, helping to control the infection. Scab removal, however, can be difficult, as not only can it be painful for horses, but the scabs are often thick, crusty and hard to remove. The following steps help to remove scabs as pain-free as possible –

• Clip the legs with fine clippers. Hair can often act as an extra surface for the scabs to attach to and can also act as barrier for getting access to the scabs.
• Use a softening cream to soften the scabs. Nettex Muddy Marvel De-Scab is an effective cream which softens the scabs making them much easier to remove. When applied to cotton wool and gently rubbed over the scabs, much of the scab will come away. It is important not to forcibly remove scabs, so any that do not come away on initial application should be left. Ensure all scabs are covered with a liberal layer of softening cream.
• Wrap legs with cling-film. This should be done with care, and if you are unsure how to do this, seek veterinary advice. Loosely wrap the cling-film around the around the affected area, over the fetlock and down the hoof. Taping it to the hoof can help prevent it from riding up. Take care not to wrap it tightly at the top.
• Bandage legs. Place a stable bandage over the cling-film layer. Horses should be stabled to reduce excessive movement and to keep the legs dry.
• Remove after 24 hours. Once the bandage and cling-film has been removed, scabs should easily come away. Wash the legs with warm water and dilute Hibiscrub (never neat) or antibacterial wash such as Nettex Muddy Marvel Disinfect.
• Thoroughly dry legs with a towel. Use a separate towel for each leg to avoid contamination.
• Apply Cream. If your vet has prescribed an antibiotic cream, apply it once the scabs have been removed. At this stage a barrier cream can also be applied, such as Nettex Muddy Marvel Barrier Cream.
• In some cases, these steps need to be repeated.

How to prevent mud fever

Mud fever can be difficult to get on top of, and prevention is always better than cure. Follow these top tips for the best chance of preventing infection –

• Avoid leaving horses standing in wet and muddy conditions for extended periods of time. Ensure they have somewhere dry to stand for at least part of the day and consider laying hardcore in high frequency areas such as gateways and around water troughs.
• Avoid over washing horse’s legs. Constant wetting and chilling of legs is a contributing factor for the development of mud fever. Washing legs results in them being cold for hours after, which we know increases the chances of developing mud fever.
• Use warm water and dry thoroughly. If you need to wash legs, make sure you use warm water and use a towel to thoroughly dry the legs. Use a separate towel for each leg to avoid contamination. Ensure you dry legs promptly and never leave them wet.
• Leave mud on legs overnight. Rather than wash off wet muddy legs when you bring your horse in, place stable bandages on overnight and in the morning brush off the dried mud.
• Trim long feathers. While you shouldn’t over clip, and expose delicate skin, trimming the feathers and coat over the lower limbs reduces the amount of mud that can stick to your horse’s legs, and also allows you better access to the skin to both observe what is happening, and treat if you need to.
• Use an effective barrier cream. Supporting the delicate skin around the pastern with a barrier cream can be useful for reducing the contact between skin and the mud. Ensure the leg is clean before applying a barrier cream such as Nettex Muddy Marvel Barrier Cream.