Mud Fever in Horses: Causes, Treatments, and Prevention Tips | Equine Science Matters™

Equine pastern dermatitis, commonly referred to as mud fever, is a skin condition caused by the bacteria dermatophilus congolensis. Mud fever typically affects the horse’s lower legs, particularly around the pastern and fetlock, but it can extend up the lower limb.

The characteristic symptoms of mud fever include scabs and sores on the lower limbs and around the heel which present as red or sore areas of skin that may weep. As the name suggests, horses standing in muddy and wet conditions for prolonged periods of time are more susceptible to mud fever (although this is not always the case) as are those horses with pink skin or white socks.

Consistent wet conditions weaken the skin's barrier allowing the bacteria to invade the skin and horses with cuts or mite damage will also be affected as this also allows the bacteria to enter the body. 

Mud fever is also referred to by various other names, including:

• Greasy Heels

• Cracked Heels 

• Scratched Heels 

• Mud Rash

Horses with pink skin or white socks are more susceptible to Mud fever

What causes mud fever in horses? 

Mud fever is a non-contagious skin condition meaning that it cannot be passed from horse to horse. Instead, mud fever is caused when weakened or damaged skin allows micro-organisms to enter and cause the infection to take hold.

There are several reasons for the skin becoming damaged, such as:

• Mites
• Abrasive surfaces like sand or rough soil
• Excessive leg washing that causes the skin to weaken and crack
• Sunburn
• Weakened immunity due to conditions like PPID (Pituitary Pars Intermedia Dysfunction)

Interestingly, the bacterium that causes mud fever acts similarly to a fungus. It can remain dormant as spores until the conditions—usually wet and muddy—are right for infection. The same bacteria can also infect the horse’s back and flanks, leading to a condition called rain scald or rain rot.

What are the signs of Mud fever in horses?

The first sign of mud fever is typically just inflammation around the infected area (often the pastern or fetlock). Sometimes redness of the skin is noticeable as a result of the acute inflammatory reaction, especially if the horse has white legs. There may be some hair loss or matted areas of hair with raw skin patches underneath and scabs will start to appear and will worsen as the infection develops. The affected area may look greasy, caused from serum oozing from the skin and this can progress to pus that hardens to crusts on the skin which harbours the harmful bacteria.

Look out for signs such as:

• Crusty scabs appearing on heels
• Broken or damaged skin
• A creamy white / yellow or green discharge between the skin and scabs
• Heat, pain or swelling around the affected area
• Lameness (in severe cases)

 Infections can easily develop under the scabs and lead to secondary issues such as Lymphangitis and Cellulitis. 

Hair loss or matted areas of hair with raw skin patches underneath are a common sign of Mud fever.

Effective treatment for mud fever in horses

There are many treatments available for mud fever and there isn’t one method that works as a ‘cure all’ but essentially you need to treat any underlying issue (such as mites), and then remove the infection and allow the skin to heal. Your vet will be able to suggest the best course of treatment for your horse.  

• As the harmful bacteria need warm, moist conditions to breed, they typically harbour under the scabs. Therefore, it is generally recommended that the scabs are gently removed by soaking them with a solution of warm water and an antibacterial skin cleanser, such as Hibisrub, and then gently, but thoroughly drying the area.
• An antibacterial cream should be applied following scab removal to support healing and act as a protective barrier to any further infection. Your vet can supply a corticosteroid cream.
• It is also helpful to apply a barrier cream before turnout.
• Often a vet will advise box rest to give the skin a break from the wet and muddy conditions in the field. If your horse is stabled, ensure he has clean and dry bedding daily.
• Clip thick feathers from the lower legs or affected areas to expose the skin to air and to make it easier to clean and treat.

It is recommended to seek veterinary advice if mud fever is suspected to ensure that the right course of treatment is followed as well as helping to reduce the risk of infection other or secondary issues. Your vet can also advise on whether antibiotics are required and can prescribe anti-inflammatory drug if necassary. 

How to prevent mud fever in horses?

Preventing Mud fever is the best way of reducing the risk of your horse from experiencing this common winter skin condition. Prevention is aimed at avoiding the underlying causes by:

• Try to avoid leaving your horse in wet or muddy conditions for long periods of time. 
• Good grassland management i.e., rotating fields to avoid poaching and using hardcore to provide dry standing. 
• Fence off muddy areas of the field to avoid horses using these areas.
• Avoid washing mud off your horses legs, it is better to let the mud dry then brush it off with a soft brush. 
• Dry horses legs thoroughly if they have been washed off.
• Use barrier creams to provide a protective layer between the skin and mud.
• Treat underlying causes such as mites, cuts or fungal infections. 
• Feed a supplement to support optimal skin health and hair growth, as damage or weakness to your horse's skin are key factors that allow the infection to take hold.

Try to avoid leaving your horse in wet or muddy conditions for long periods of time.

 Best supplements for Mud Fever prevention

For horses prone to Mud Fever, Feedmark’s EquiDermis offers natural support to promote optimal skin health and hair growth. This supplement is designed for horses facing wet, damp, or muddy conditions and works from the inside out by delivering essential nutrients for strong, resilient skin and a shiny coat.

EquiDermis contains a potent blend of beneficial herbs, including Burdock Root, Nettle, Clivers, and Chamomile, along with Brewer’s Yeast. These ingredients are combined with a base of Micronized Linseed and Linseed Oil, which provide a rich source of Omega-3 fatty acids and B vitamins to support healthy skin and hair.

The selected herbs help:

• Soothe irritated skin
• Strengthen hair growth
• Counteract dryness

Additionally, Calcium Carbonate is included to balance the crucial calcium-to-phosphorus ratio, ensuring overall well-being.

This powerful formula helps your horse maintain resilient skin and a glossy coat, providing essential support in challenging conditions.