At this time of the year, mud rash/fever and rain scald are common problems. Many of you will struggle with these conditions so here is some information about the cause and treatments available.
Both rain scald and mud rash are caused by the bacteria Dermatophilus congolensis. This organism lives in the environment as spores which are activated by wet weather, hence the association of the disease with rain. With prolonged wetting, the outer layers of the skin become softer and more susceptible to external trauma. This means the skin acts as less of a barrier to infection, enabling bacteria to live and multiply within the skin.
Certain individuals seem to be more susceptible than others to the disease. This may be a genetic factor.
Horse with feathers on their legs seem to suffer less as their legs are protected by a layer of hair. Horses with white pasterns or legs which have pink skin seem to suffer more as the skin is less protected.
Signs of the disease
These conditions are usually easy to diagnose, based upon the appearance of the horse’s skin. Sometimes we may take a swab from the affected area to confirm diagnosis.
- Mud rash – This often appears on the backs of horse’s pasterns and fetlocks. It starts as matted hair with dry crusts and progresses to swollen, moist weeping lesions. If the crusts are removed at this stage, there is often a moist pink, painful skin surface beneath, sometimes with some pus. In it’s extreme form, mud fever can cause considerable leg swelling and the horse may become lame
- Rain Scald – This often appears on the horse’s back and neck. It follows the pattern of the horse’s coat as the rain runs off it. There are similar scabs to thos seen with mud rash and once these are removed there may be pus found sitting under the scab.
To treat these problems successfully the horse must be kept in a clean, dry area. Loose scabs and crusts should be removed and the hair in the affected areas clipped. If the scabs are too firmly attached to remove, they should be soaked in dilute Hibiscrub or Pevidine. Remove all scabs, crusts and hair from the stable to prevent re-infection.
- The lesions should be cleaned twice a day with dilute Hibiscrub
- If the infection is deep in the skin, we sometimes need to examine the horse so we can prescribe antibiotic cream. The lesions should be washed, then thoroughly dried before applying the cream
- Keep the horse on dry bedding
- In severe cases the horse may need to be put on a course of antibiotics to get on top of the infection. This may be via injections or oral powder or paste
Prevention is very difficult, but here are several ways to help reduce the chance of your horse contracting these disease:
- Avoid exposure to moisture – Prevent the horse having too much contact with mud or rain. Use New Zealand rugs to keep them covered up and try to have a solid floor surface around water troughs to prevent a mudbath developing
- Barrier Creams – There are lots of these creams on the market. Apply them before your horse is turned out, aiming to prevent the mud getting in contact with the skin. Thick creams are often best, such as Sudacrem or even Cow Udder cream! Thinner, more watery creams tend to make less reliable barriers
- Skin care – People tend to wash mud off a horse’s legs when it comes in at night. This may just soften the skin further and exacerbate the condition. It is probably best to allow the mud to dry and then brush it off with a dandy brush