How to deal with mud rash and rain scald in your horse or pony

Mud rash and rain scald- many horses and ponies are prone to these uncomfortable and sometimes painful conditions, particularly during the winter months when the weather is bad and the ground is muddy. If your horse or pony grazes in a muddy field, is often ridden in wet and mucky conditions, and especially if they have white socks on one or more of their legs, then it’s important to keep an eye out for the signs of mud rash. Similarly, prolonged exposure to the elements can potentially lead to rain scald along the exposed areas of the back and neck of susceptible horses, and both conditions can affect your horse’s general wellbeing, cause pain and discomfort and lead to inflammation of the skin and loss of hair.

What causes mud rash and rain scald?

Both mud rash and rain scald are caused by the presence of a bacteria called Dermatophilus congolensis. This bacteria is naturally present in the environment as inert spores that are activated by rain and wet weather, which is why both mud rash and rain scald are associated with mud, rain and damp conditions. Prolonged exposure to mud and rain, such as when standing in a muddy field or grazing in heavy rain for prolonged periods of time can cause the upper layers of your horse’s skin to become softer and more prone to damage and sources of infection. It is not definitively known why some horses are more susceptible to the bacteria than others, but it is thought that genetic factors may play a part. Certainly it’s very common to find that in a group of horses grazing the same land or kept in a similar manner, a couple of them may become affected whereas others in the group will be totally fine.

Mud rash and rain scald can occur simultaneously, although often an affected horse or pony will only suffer from one condition or the other.

Horses with pink skin and/ or white legs are generally much more susceptible to mud rash than horses with darker coloured limbs, and light coloured horses and ponies such as palominos and greys are similarly more likely to suffer from rain scald.

Preventing mud rash and rain scald

Once mud rash or rain scald have taken a hold, they can be difficult to eliminate or control, as it is often not feasible to remove your horse or pony totally from the source of the problem such as a muddy field or rainy conditions! There are some preventative measures you can take to minimise the likelihood of either condition developing, although none of these are foolproof and you may eventually need to consider moving your horse or pony into a dry stable to control and treat either condition.

Avoid damp, mud and moisture

This is understandably easier said than done! But if your horse or pony’s grazing land is particularly damp and muddy, consider moving them to a field with better drainage. Points where horses congregate, such as near to the gates at feeding time are often particularly muddy, so blocking these areas off can help. Keep susceptible horse’s backs and necks dry with waterproof New Zealand rugs to minimise the exposed surface of the upper body and so minimise the likelihood of rain scald developing.

Don’t make the problem worse with water

Many horse owners will wash off their horse’s muddy legs when they come in, thinking that this will help remove the source of the problem. However unless you are prepared to dry the legs thoroughly, this is unlikely to help. Either dry the legs after washing, or wait until the mud is dry and then brush it off.

Try using a waterproof barrier cream

You may find some success by using a thick, oil based barrier cream such as Sudacrem on your horse’s legs and other affected areas before they are turned out. It goes without saying of course that the skin must be bone dry before doing this, otherwise you will only serve to trap moisture next to the skin.

Diagnosing mud rash and rain scald

Identifying the presence of either mud rash or rain scald is fairly straightforward for any owner to do, although you might of course wish to have your vet confirm diagnosis by testing a skin swab from the affected area.

Rain scald

Rain scald generally appears on the horse’s back and neck, particularly in areas where the rain runs off the coat. Matted, dry hair with scabs underneath which eventually turn into moist lesions with a weeping discharge are the main indicator of rain scald.

Mud rash

Mud rash generally appears on the back of the affected legs around the fetlocks and pasterns. The appearance of mud rash is similar to rain scald, with dull hair covering scabs, which disguise lesions and sore, pink skin. If left untreated for a prolonged period of time, mud rash may cause swelling and hypersensitivity of the affected areas of the legs, which can lead to lameness.

Treating mud rash and rain scald

In order to successfully treat mud rash or rain scald, the most important element of treatment is removal of the source problem- exposure to wet, damp or muddy conditions. You may even need to consider stabling your horse or pony full time in order to do this.

• Clipping off thick hair covering the scab and lesions can make treatment easier, and minimise the amount of moisture which the coat harbours next to the skin.
• Scabs, crusted areas and the lesions themselves all harbour bacteria, and so must be removed, both to prevent re-infection and the spread of the condition, and to allow the skin to breathe and dry naturally. Generally the scabs will come off relatively easily, although you may need to soak them in an antibacterial rinse to loosen any new scabs.
• Clean all of the affected areas and lesions, plus a small border around the affected area, with an antibacterial scrub such as Hibiscrub (chlorhexidine) or Pevidine twice a day.
• Thoroughly dry the skin after cleaning. Be sure to use clean towels to avoid re-introducing the bacteria into the lesions, and remove all scabs, hair and other detritus from the stable for the same reason.
• Apply an antibiotic topical cream which your vet can provide to promote healing.
• Keep your horse’s bedding thoroughly dry at all times.

Generally, following the above steps will be enough to successfully treat mud rash or rain scald, although in severe or resistant cases, you may need to consult with your vet about prescribing a course of antibiotics to assist with healing.

If you are unsure of the best course of action to take or need any help and advice in dealing with mud rash or rain scald, contact your vet for help.