How to spot summer pasture allergy

The low-down on common winter skin conditions

All riders dread wet, muddy winters, but these conditions can be especially awful for your horse’s skin. We asked Petplan Equine veterinary expert Gil Riley to explain why issues such as rain scald and mud fever seem to flourish at this time of year. Plus, he shares his top tips for keeping your horse’s skin healthy throughout the colder months.

What’s to blame for winter skin problems?

According to Gil, the answer is simple: the weather – especially in the UK, where our wet winters increase moisture levels in the environment. ‘This creates conditions that break down the protective oily layer on a horse’s skin, allowing bacteria to thrive,’ Gil explains. ‘The thicker rugs we use in winter can also lead to sweating, again increasing dampness and moisture. And horses that share rugs are particularly prone to skin infections, as rugs can easily transfer bacteria.’

What makes horses so prone to skin conditions?

‘Your horse’s skin is the largest organ in his body,’ Gil says. It’s his first defence against moisture, abrasive substances such as dirt and grit, parasites and bacteria, so problems are common. ‘Keep in mind that, depending on the skin condition, it can be very painful for your horse,’ Gil advises. ‘And, as a condition worsens, it can lead to a secondary infection which causes additional stress for your horse. However, the right treatment can turn things around quickly.’

Here’s how you can tell the difference between the most common skin conditions, plus Gil’s advice on preventing your horse from developing them in the first place:

Rain scald and mud fever

‘These are both bacterial infections,’ Gil explains, ‘but rain scald affects a horse’s back, the sides of his chest and hindquarters, whereas mud fever affects the legs.’

Rain scald will appear as scabs, often with tufts of hair attached to them and sore-looking pink skin in between. The scabs may vary in size and are not usually itchy. ‘Resist the temptation to pick at the scabs,’ Gil says. ‘They may be unsightly, but removing them can be painful for your horse and cause the area to bleed. It might also make your horse reluctant to let you near those areas again!’

Similarly, mud fever will show up as scabs on the legs, and could cause lameness if the scabs form around the heels and coronet band. In severe cases, mud fever can lead to a deeper skin infection and may cause swelling in the leg.

Prevention and treatment

‘Rain scald thrives under rugs, so try not to over-rug as this causes sweating,’ Gil says. ‘Change rugs regularly, avoid sharing them (as well as brushes and tack) between horses to prevent cross-infection, and make sure your waterproof rugs keep the rain out. Clipping your horse’s winter coat will help to reduce sweat, too.’

Mud fever is more likely to happen when turnout is wet, especially where standing water is found – such as at gates where horses wait to be brought in. Improving drainage and laying down gravel will help.

‘If your horse is prone to these conditions, clean his rugs or leg wraps regularly with antibacterial washes and wet wipes,’ says Gil. ‘Treat affected skin daily with a disinfectant that’s been diluted with warm water, making sure to gently dry the area with a clean towel. A steroid cream from your vet can also help, and it may be necessary for your vet to give your horse an antibiotic. Most vets will recommend that you keep your horse in his box (and therefore dry) while he undergoes treatment.’

Lice and mange

Parasites such as lice and mange commonly affect breeds with longer hair. Horses with Cushing’s disease (a condition where too much of the hormone cortisol is produced, leading to a weakened immune system) are also more susceptible. Lice are very small and hard to spot, but the most common sign you’ll see is your horse itching.

Mange is caused by a mite that feeds on the debris on the surface of the skin, and is particularly attracted to the feathers of the lower limbs (hence the name ‘feather mite’). ‘The mites crawl along the skin, which is very irritating for a horse, causing him to stamp and rub his lower limbs. It can lead to a horse inflicting injuries on himself, which can become quite severe, causing pain and potentially lameness,’ Gil says.

Prevention and treatment

‘Lice and mites love warmth and moisture, so, again, try to make sure you don’t over-rug,’ Gil recommends. ‘You may also need to isolate a horse that has lice, as these parasites pass easily from one horse to another.’ Lice are small and can be difficult to spot if a horse isn’t clipped. If you do suspect them, treat your horse with a lice powder. As the powder only kills off adult lice and not eggs, keep in mind that you’ll need to treat your horse again in 10 to 14 days to kill off any that have hatched in the interim.

However, if you suspect mange, seek veterinary advice straight away. ‘Your vet is likely to treat your horse with a wormer that is licensed for cattle, which is injected under the skin. This will be followed by a second treatment after 10 days, again to catch any that will have hatched in the meantime,’ Gil explains. ‘Stable bedding can be a reservoir for mites, so it should be fully removed from the stable of an affected horse and burnt to prevent reinfection.’


Ringworm is a skin infection caused by a dermatophyte (‘skin loving’) fungus. It causes skin lesions that usually start as small raised spots from which the hair is lost. The spots can spread and a thick, dry and crumbly scab may form. It’s easy to confuse these scabs with rain scald, so speak to your vet as soon as you see the symptoms. The ringworm fungus can live in the environment (for example in rugs and wood fixtures around the stables) for up to 11 years and is also highly contagious, and can infect whole groups of horses in an outbreak.

Prevention and treatment

If you suspect your horse has ringworm, isolate him immediately to prevent the infection from spreading. Treatment is straightforward. Gil says: ‘A fungicidal wash will effectively treat ringworm, and your horse’s hair will grow back within six to eight weeks. Also wash any areas of the stable that your horse was in contact with and all his rugs with the fungicidal before reusing them.’


‘This is usually a bacterial infection of a horse’s hair follicles,’ Gil says. ‘It’s most common in a horse’s saddle area, and thrives in warm wet conditions, so keep a look out for it under rugs and as we head into spring.’ A tell-tale sign of folliculitis is clusters of small red bumps or pustules that develop around hair follicles. These can break open and crust over, leaving your horse’s skin feeling painful and tender.

Prevention and treatment

‘Again, think about rugging no more than is necessary in order to keep your horse’s coat sweat-free and dry,’ Gil says. ‘If your horse has contracted the condition, your vet will prescribe a longer-than-usual course of antibiotics, along with daily bathing of the area with warm water and disinfectant. With treatment, folliculitis should clear up within 10 to 14 days.’


‘Compressed soil with poor drainage provides conditions where bacteria can thrive, which can then infect a horse’s foot – specifically the troughs of the frog and the crevice between the heel bulbs,’ says Gil. A common sign of thrush is a smelly, black discharge. While a horse with the condition isn’t likely to be in pain at first, it can penetrate further into the foot and begin to cause him distress.

Prevention and treatment

‘Good foot care, centred on twice daily picking-out of the crevices of the hooves, is essential,’ advises Gil. ‘Regular trimming and shoeing will also help to prevent thrush. If your horse does get thrush, your vet or an experienced farrier will need to trim away any under-run horn and open up the affected tissues to the air. They’ll then prescribe box rest in clean and dry conditions, sometimes in conjunction with antibiotics, to treat the condition effectively.’