I heard on the news recently that last year was one of the wettest on record. I don’t know if it’s true – but it certainly feels about right! The big danger to our horses from this, of course, is Rain Scald and Mud Fever.
Most people have probably come across Rain Scald on occasions – the scabs hidden away in the coat feel like mud, until you pull them up and see the characteristic “paint brush” appearance as the hair stays stuck in the scab. Rain Scald is caused by a bacterium called Dermatophilus congolensis. This usually lives (fairly) harmlessly on the skin, but if the skin gets and stays wet, the bacteria can invade and set up an infection.
Most cases are mild, with just a few scabs here and there, but (especially in older horses and those with Cushing’s disease) it can be more general and leave large raw patches. Even a mild case can put a horse “off games” if the scabs or raw patches are under the saddle.
Most cases resolve on their own with simple care – gently brush out the scabs, and most importantly keep the area dry to allow it to heal. That said, older horses and those with other diseases may need a helping hand, in which case a short course of antibiotics from your vet will usually clear it up. HOWEVER… Unless the underlying problem is sorted, it will rapidly return! Prevention is far more important, and that means keeping the skin as dry as possible. Remember, if your horse gets wet, that’s fine as long as he can then dry out thoroughly. It’s if the skin stays constantly wet that problems ensue – and watch out for rugs, especially in early autumn! When it’s wet, but not that cold, horses can easily sweat up under their rugs, and sweat seems to be even worse than rain for causing Rain Scald.
The other thing to watch out for, of course, is Mud Fever. This is an infection of the skin behind the heels (its sometimes called Greasy Heels), and is most common in horses with long feathers. It’s a far more complicated disease than rain scald, and has a large number of contributary causes. The most important is wet weather, of course – as the skin gets wet, bacteria can invade, as in rain scald – long feathers keep the water trapped in the area, slowing down the drying, so cobs and heavy horses are more prone. However, mites are also a known cause (the first signs are usually stamping of the hind legs), and its not just bacteria, because some cases include yeasts and other fungi as well. Sometimes, really aggressive bacteria like Pseudomonas can establish themselves, and they can be really difficult to manage.
The symptoms vary, but generally it first presents as scabs in the angle of the heels behind the pastern. If untreated, or as the infection gets worse, cracks in the skin can open up and start oozing fluid and pus, and the legs thicken. Eventually, lymphangitis can occur and ultimately, the skin can slough or even become gangrenous.
Initial treatment is very simple: wash the affected area with a skin disinfectant (like Hibiscrub or similar), and once the scabs are softened, gently wash them off. This may take several days of work! If the infection progresses, or doesn’t improve, you will need veterinary attention.
Most cases respond well to a course of first-line antibiotics (e.g. Penicillin/Streptomycin or Timethoprim Sulpha); however, if it doesn’t respond in a week or so, I would always take a swab for bacterial culture and sensitivity testing. This give you a much better idea what bacteria you’re dealing with, and how best to kill them – I had a case once which turned out to be a multi-resistant Pseudomonas infection, that needed some really powerful off-license antibiotics to resolve it. Sometimes you can use topical antibiotics (creams, ointments etc), and in severe cases, I have occasionally used a “bespoke” ointment that I made up from several different antibiotics and an anti-inflammatory. If there are mites involved, most vets will use an injectable anti-mite drug; however, this isn’t licensed for use in horses so has to be put up by your vet.
As usual, prevention is much better (and cheaper!) than treatment, though, so keeping the heels dry is vital. Sometimes using an aqueous cream like zinc and castor oil, or Vaseline, can be useful in encouraging the water to run off – but if you do use them, make sure you wash it off and dry it thoroughly once or twice a week before reapplying, so it doesn’t get too thick.
Of course, in an ideal world, keep the horses out of muddy fields and trackways… But given the recent weather, I fear we’re all going to have to be a lot more careful to keep our horses and ponies warm and dry this autumn.
If you are worried about any symptoms your Horse or pony may be displaying please talk to your vet or try our Interactive Equine Symptom Guide to help decide what to do next.