Mud Rash

 MUD, GLORIOUS MUD!


Not surprisingly at the moment, we’re talking to a lot of clients about mud rash and rain scald.  And many of you are no doubt struggling with horses with these conditions, so here is a little 

refresher about these diseases for you…


The bacterium Dermatophilus congolensis causes both mud rash and rain scald.  This organism lives in the environment as spores, until they are activated by wet weather. This is why we see the disease associated with heavy rainfall.  Moreover, with prolonged wetting, the outer layers of the skin become much softer, and are more susceptible to external trauma.  The skin is then less able to act as a barrier to infection, enabling the bacteria to live and multiply within it.

Nobody really knows why certain horses are more susceptible to mud fever than others.  It may be that certain individuals are not as good at fighting the disease, and therefore show much more severe signs than others. Susceptibility may also have genetic factors.

In addition, the disease is obviously made worse the wetter and muddier a horse gets.

Horses with hairy legs often suffer less, as the skin is that bit-more protected. Horses with white, or hairless pasterns with pink skin seem to suffer more as the skin is much less protected.

 Signs of the disease

These conditions are usually easy to diagnose, based on the appearance of the horse’s skin.  Sometimes we will take a swab from the affected area to confirm the diagnosis.

  • Mud rash
    Often appears on the backs of horse’s pasterns and fetlocks.  This will start off as matted hair with dry crusts, and progress to swollen moist weeping lesions. If the crusts are removed at this stage there is often a moist pink sore skin surface and some pus underneath.  In its extreme form, this will cause considerable leg swelling, and consequently the horse can be very lame.

  • Rain scald 
    Often appears on a horse’s back and neck, and follow the pattern of a horse’s coat as the rain runs off it.  There are similar scabs to those seen with mud rash, and again when these are removed, there is often a large amount of pus sitting under the scab.


 Treatment

These diseases are made so much worse by rain and mud, so to treat them successfully the horse must be removed to a clean dry area. Loose crusts and scabs should be removed and the hair in the affected areas clipped.  Where scabs are too well attached to be removed, they should be soaked in dilute Pevidine or Hibiscrub.  All the scabs, crusts and hairs should be removed from the stable to prevent re-infection.

  • The lesions should then be cleaned on a once or twice daily basis with Pevidine, or similar solution.  If the infection is deep in the skin, we sometimes need to examine the animal so we can prescribe antibiotic cream.  In these cases, having washed the lesions, and thoroughly dried them, the antibiotic creams should be applied.  The horse must still be kept on dry bedding throughout treatment.

  • In severe, or extensive cases it is often necessary to put horses on antibiotics in order to really get on top of the infection. These can be administered either by injection, or using powders by mouth (a mint-flavoured version is available for fussy eaters)


Prevention

Prevention is very difficult.

  • Avoid exposure to moisture  
    The key is to prevent the horse getting too much contact with mud, (in the case of mud rash), and rain in the case of rain scald.  We do appreciate how difficult this is, particularly with the present weather conditions.

  • Barrier creams  
    There are numerous barrier creams and powders marketed.  The aim is to apply these to your horse’s legs before you turn him out, and they prevent the mud getting in contact with the skin.  These all work to a greater or lesser extent, so find which works best for you and stick to it.   As a general rule, because the cream is working as a barrier, the aim is for it to keep water from contact with the horse’s leg.  Therefore the best creams such as Sudocrem are thick and oily. Thinner, more watery products tend to make less reliable barriers.

  • Skin care  
    A lot of people wash the mud off a horse’s leg when he is brought in at night.  This may just soften the skin more and exacerbate the condition.  It is probably best to allow the mud to dry and then brush it off with a small dandy brush.


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