Rain Scald
Rain scald is a skin condition that affects horses mostly during autumn and winter months. It is caused by bacteria called Dermatophilus congolensis, which can live quietly in the skin but prolonged wetting by rain, high humidity, and high temperature can increase its occurrence. The lesions caused by dermatophilosis usually localise on the back, flanks and rump.
Horses that are kept outdoors without a rug in rainy conditions are those that are most commonly affected. However this condition can be also found in horses that are over-rugged, as this can cause excessive sweating.
Rain scald is characterised by scabs coming off with tufts of hair, that look like paint brushes. The scabs may vary in size and there may be yellow pus on the skin underneath the scab. The scabs can be painful but are not usually itchy.
This condition affects mostly young horses, those with weakened immune systems or animals continually exposed to moisture.
Diagnosis is made by clinical exam and can be confirmed in a laboratory by sending the scabs for culture or microscopy.
Dermatophilosis is contagious between horses and therefore tack, rugs and brushes shouldn´t be shared between affected and non-affected horses.
Treatment:
- Bring your horse indoors away from the wet conditions. If it is not possible, protect your horse with a waterproof rug from the rain.
- If your animal is very hairy, gently clip the hair in the affected areas.
- Carefully remove the scabs using a diluted chlorhexidine soap (hibi-scrub) or povidone-iodine soap (betadine), keep the solution on for about 5-10 minutes and then remove it with swabs soaked in clean water. Dry the area thoroughly and apply either sudocrem or antibiotic cream in more severe cases.
- In horses with badly affected skin, systemic antibiotics may be necessary.
- If the rain scald is complicated by fungal infection, your vet may recommend using antifungal solutions.
- Wash grooming brushes, rugs and tack in a disinfectant to avoid re-infection.
- Avoid riding your horse or pony until the lesions are completely healed.
Prevention:
- Protect your horses from wet conditions by using a waterproof rug or providing them with shelter. However, also avoid over-rugging your horses.
- Don´t share rugs, tack and brushes between horses if there is a suspicion of an infection in one of the animals.
- If possible, on rainy days bring your horse indoors for a time to allow the skin to dry and protect from prolonged wetting.
- Regular grooming is recommended to remove excessive mud as the bacteria can multiply under the clumps of dirt.
- Horses with Cushing´s syndrome have got compromised immune system and therefore if your horse suffers from recurrent infections it is recommended to have them tested for this condition.
- Regular inspection of the skin is necessary to discover the rain scald and in case you are concerned about your horse, pony or donkey, don´t hesitate to contact your vet.
Case Study
Arika was kept in a field without a rug in autumn in extremely wet conditions. Even though she had a shelter in her field, she had weakened immune system due to her older age. Due to owner´s illness, he couldn’t inspect the horse´s skin regularly and when he got better, he found several scabs on Arika´s back that were coming off with tufts of hair and looked like paint brushes. There was also yellow pus underneath the scabs.
The Vet attended the horse and took samples of the skin and found out that the rain scald caused by Dermatophilus congolensis was also complicated by mycosis and therefore suggested cleaning the affected areas with povidone-iodine, applying antibiotic cream and spraying the skin with antifungal solution.
Arika´s skin is now healing very well and she is again a happy old mare.
