Q: Each year, since my 16-year-old mare was four, she’s had a mild case of facial hair loss and occasional blistering. This year it started with a small patch the size of a 50p piece and after 24 hours most of her face was blistering.
The vet treated her with antibiotics, which cleared the infected areas, but the hair loss and swelling continued, so she was put on steroids. On a later visit, he explained she was affected by the high pollen counts we’ve been experiencing and she has a contact allergy to grass pollen.
She was taken off the grazing and has since been clear of the blisters. Is there anything I can do to prevent this happening year after year?
Jo Holmes MRCVS replies: If the condition affecting your mare occurs seasonally and is quite predictable, it is likely she’s allergic to something in her environment, such as pollens.
Prevention is better than cure and keeping her in during the crucial period is your best strategy.
I’ve been impressed by the Boett Blanket which has assisted many horses I know in the fight against sweet itch. The blanket fits closely over the body. Face hoods are also available. Make sure the hood has holes for your horse’s eyes as netting is thought to cause eyesight problems.
You could try moving her to different, re-seeded grazing where the irritant grasses may not grow.
Your mare may have photodermatitis (a skin reaction to ultra-violet light) or it could be simple sunburn, which occurs on pink skin and facial areas. Otherwise, the skin may have been sensitised by your horse eating certain plants in the pasture known as epyrrolizidine alkaloids.
These get processed by the liver and end up as toxins deposited in the skin, which then react to sunlight.
Antibiotic and steroid creams should help, as will sunblock if it is applied thickly enough. Experiment to see what helps.
If you’re worried plant toxins are to blame, ask your vet to blood test your mare to check her liver function.