Mud Fever

February 2021

Endless rainy days have become a typical feature of winter, meaning our horses are more likely to be spending time in wet, muddy paddocks, which can increase their risk of developing mud fever. This is a non-contagious (which means it doesn’t spread from one horse to another or to people) skin condition that causes irritation, soreness, matted areas of hair and scabs that form on the horse’s lower legs. You may also hear it referred to by a few other names, including dermatitis, greasy heels and cracked heels. 

Mud fever commonly forms on the pastern (between the fetlock and the hoof) and the heel. Infections can develop underneath the scabs and you may see swelling of the leg in severe cases. Mud fever can be painful, and the horse may not tolerate the area being touched. Pink skin under white legs can be more commonly affected compared to dark skin


mud fever

Cause

Mud fever is most often caused by bacteria and is common in the winter months when the horse is exposed to persistent wet, muddy conditions. This is because the wet conditions cause the skin to soften and mud rubs against this softened skin causing damage to the surface where bacteria can enter. There can be other causes of mud fever such as leg mites which break the skin and enable bacteria to enter. Horses with feathers are more at risk of leg mites and you will see them stamp their legs because they’re very itchy. If you suspect your horse has mites, speak to your vet for further advice.

Risk factors

There are a few things that can compromise your horse’s skin and lead to mud fever taking hold.

  • Standing in muddy or wet conditions for long periods
  • Standing in dirty bedding
  • Regularly washing the legs, especially if you don’t dry them afterwards- There are many differing opinions as to what to do with wet, muddy legs. It is recommended to allow the mud to dry and then brush it off. If washing is required, then it is important to thoroughly dry the skin
  • Having broken or damaged skin due to a wound, such as an overreach injury.

Some horses are more prone to developing mud fever, and this is because they may have:

  • White legs - pink skin under white markings is often more sensitive than dark skin
  • Thin skin such as Thoroughbreds or Arabs, which can be damaged more easily, giving bacteria a way in
  • Having a weakened immune system – which is usually secondary to another condition, such as Cushings Disease. Horses with a lowered immune system are less able to prevent and fight off infections, so are more prone to health conditions. If these horses suffer from mud fever, it can be more difficult to treat.

Signs

It’s really important to check your horse’s legs every day, so you get to know what’s normal for them and to make sure you spot any signs of mud fever straightaway - it should be easier to manage if you catch it in the early stages.

Common signs of mud fever include:

Crusty scabs appearing on the heels or lower legs.

mud fever

Broken and damaged skin.

mud fever

Matted hair or patches of hair loss with raw skin underneath.

mud fever

A creamy white, yellow or green discharge between the skin and the scabs.

mud fever

Heat, pain and swelling in the lower limb.

mud fever

In severe cases lameness 
may also be seen.
Walking up with horse

Credit: mud fever images VetPartners.



Treatment

It is important to call your vet as soon as you spot any signs of mud fever, so they can give you an accurate diagnosis and make sure treatment is tailored to meet your horse’s needs. Once your vet has made a diagnosis and recommended a treatment plan, they should be happy for you to continue managing the condition yourself. However, you should get back in touch with them if your horse fails to respond to treatment, or the mud fever gets worse.

A general treatment plan should include:

  • Bringing your horse in out of the muddy and wet conditions to keep your horse’s skin clean and dry
  • Removing the scabs to help you gain easier access to the skin and to allow air to reach the skin to help the area heal. However, if you choose to do this proceed with care as it can be very uncomfortable for your horse and sedation may be necessary. Any loose scabs may be gently removed, but scabs should not be forcibly removed unless advised by your vet
  • Clean the affected area at least twice a day using a mild disinfectant, such as dilute Hibiscrub, then rinse with water and pat the leg dry with a clean towel
  • If your horse has thick feathers you may need to carefully clip the hair from the lower leg to expose the skin to the air and make it easier for you to clean and treat it
  • Applying stable bandages to dry legs can help keep them clean, provide support and reduce any potential swelling
  • Severe mud fever may require repeat treatments and cream applied to the skin. Your vet will be able to advise the course of action and treatment plan
  • If mites or a fungal infection have triggered the mud fever, individual treatment for these causes may be required.

In more severe cases, a blood test may be required to identify an underlying disease. If the mud fever isn’t clearing up, a swab can also be taken to check for bacterial growth and sensitivity, allowing for the appropriate use of antibiotics. Anti-inflammatories may be recommended by your vet, depending on the clinical signs and overall health of your horse.

Prevention

There are many ways to reduce the risk of your horse developing mud fever, and they are all aimed at avoiding the underlying causes.

  • Avoid your horse standing in wet and muddy conditions for long periods – make sure they have somewhere dry to stand for at least part of the day
  • Adopt good grassland management by rotating fields to reduce poaching and put hardcore down in places where horses gather, such as gateways and water troughs. Fence off any particularly muddy areas
  • Avoid washing off your horse’s legs when you bring them in from the field and instead wait until the mud is dry, then brush it off using a soft bristled brush. If you do wash your horse’s legs, dry them thoroughly afterwards using a clean, dry towel
  • Barrier creams can be used prior to turnout, to create a protective layer between the skin and the mud. However, be wary as they can provide a perfect environment for bacteria to grow in between the skin and the cream
  • There are boots designed for turnout, to prevent mud getting to your horse’s legs, but it’s important that they are well-fitting to avoid rubs and sores which may cause more of a problem
  • Treat any underlying conditions such as mites, fungal infections or wounds
  • If you have an older horse, be aware of an increased risk of Cushings Disease. Speak to your vet for further advice
  • Inspect your horse's legs every day to spot problems as early as possible.

Did you know?

Mud fever can also occur in other areas of the body, such as on the belly, and on the back where it is called rain scald. Rain scald can also be triggered by spending long periods in damp, mild conditions, or from excessive sweating under tack or rugs.


With thanks to VetPartners, Katherine Hall BVSc MRCVS and Matt Swarbrick BVSc (Hons) CertAVP MRCVS. The Minster Equine Veterinary Clinic.

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