We have a horse in the barn diagnosed with leukocytoclastic vasculitis - it shows up on this horse as what looks like terrible mud fever on the white legs, but primarily between hock and pastern. We are getting it under control with steroids and bandaging, but I am interested to know whether anyone has experience keeping this from flaring up in the first place. The vet suspects a sensitivity to something in the hay or pasture, making the horse extra photosensitive, and has suggested that the horse wear some sort of UV protective boots once things heal up. I’d love suggestions if anyone has any please. Would plastering on a sunscreen cream of some sort do the same job, like we do for pink noses?
It could be worth a try…there are also the silver socks for horses that might help. Do you have yellow buttercup (ranunculus) in your fields in the spring? I did some research when I got my pink-skinned horse, and it turns out eating the yellow buttercups can cause photosensitivity for some horses.
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Thankfully no buttercups in our fields! We do have clover though, and it could easily be a photosensitivity trigger too.
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How about something like the ShooFly fly boots? They aren’t necessarily UV protecting but I wonder if they would serve the purpose to decrease some of the UV exposure as well as providing a “barrier” between the horse’s legs and the possible allergen plant?
I have a horse that tends to get scratches on his hind legs and I do feel having his ShooFly’s on 24/7 helps keep some of the moisture off his feet.
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ShooFlys have been sufficient for our otherwise sensitive white-legged horses (but we do also have buttercups so particular to that kind of photosensitivity).
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My horse was diagnosed with this same thing two summers ago ago now. Here’s how I manage.
The flare ups/sores were resolved with the steroid spray. Nothing else. No antibiotic wash or creams or anything just the steroid spray twice a day and they resolved.
We never, ever clip his white legs. The hair offers protection.
He wears fly boots (shoo fly brand) 24/7 (he lives in an outdoor paddock).
This management has resulted in zero flare ups since he was diagnosed after we got that under control - probably took a few months of knocking out a flare with the steroid spray every few weeks. In the two years since then I think I’ve had to use the steroid spray twice (like two actual times not two courses - and it may just have been a regular cut/scab and I was just paranoid).
edited to add:
the steroid spray is gentamicin spray
We also put him on a monthly injection of Eqstim which is immune system support
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My gelding has this, white hind leg, in the late summer. Agree steroid spray and fly boot which cuts the UV enough that no issues the last two summers. My vet speculated it’s white/Dutch clover is the sensitizing agent.
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I had an issue with turnout boots or mud fever boots causing some sweating which then led to scratches, even when on for only part of the day and taken off and leg cleaned and dried after.
The Equiderma Zinc paste is great at protecting the leg from bugs and sun at least while you are healing and medicating them. I was putting a broader spectrum ointment with steroid on clean legs then the Equiderma Zinc on top. Once healed, fly boots would probably work fine and not have the issues with sweat like a mud fever boot.
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I feel like my ShooFly boots do ward off scratches.
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Buckwheat can also cause photosensitivity.
What is the steroid spray? I have a guy with persistent scratches.
Has the horse’s liver been tested?
Vitamin E can reduce photosensitivity, but all in all, I hope the owners invest in figuring out the root cause rather than just covering the white.
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Went through this with my mare when she was young (ages 2-4)
Dexamethasone, wrapping (no sunlight on them while they are healing) and gently massaging the legs in-between wrap changes healed her up.
The silver whinnies socks mentioned do help and work, but they are a pain to keep from falling down. You need to figure out which electrical tape taping method is gonna work for your horse.
What do I do?
Avoid alfalfa like the plague.
I was feeding my mare alfalfa cubes when she flared so badly. The hay she was eating was also heavy in it.
Cut it from her diet and no massive flares.
On top of that I did not clip her legs for years. I have not used boots or socks. I did clip her legs last summer and had no issues.
Diet changing was the most important.
I also found as she has grown older, and I have treated her other allergies (clover, weeds and grasses… she gets bad grass mumps… Use hydoxyzine in the summer) she hasn’t had any issues.
Good luck!
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Could I ask what the steroid spray is specifically please? That isn’t something we’ve been offered for this horse. We’ve been using hydrocortisone creams so far, and had good luck with flamazine settling down some of the really angry redness.
No buckwheat with this horse, that I am aware of. Something to keep an eye out for though, so thank you 
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First step is getting the poor horse’s legs sorted, then nailing down what precipitated the reaction. We’ve had an all-clear, veterinary-wise, aside from the vasculitis on the legs. Our very good vet is pretty confident that it is an allergen/photosensitivity situation.
Thank you for this! The horse in question first developed a few spots in late fall, and I’m afraid we didn’t recognize what we were dealing with, so treated it as we would any other scratches or mud fever. Being slow on the uptake with recognizing what what actually going on means it has taken a lot longer to get under control than it might have otherwise, as we weren’t quick to add the steroid component.
How did you decide that alfalfa was the trigger? Allergy testing or just looking closely at diet and flare ups?
Yes it is a gentamicin spray. Looks like some come as a combo with betamethasone and I don’t remember if mine did, but primarily it was the gentamicin.
I spent 6-8 months treating it like scratches - washing with antibiotic shampoo, mixing up all kinds of combo goops, and it could just never get under control. I finally strong armed my vet into a referral to Davis where their dermatologist did a biopsy and gave this diagnosis. Once the gentamicin got it under control and I kept him in fly wraps it’s been smooth sailing. He was on alfalfa cubes but coming off alfalfa didn’t help, and going back on alfalfa hasn’t been a problem.
edited to add, we are also in California in the land of no turn-out, so it’s also not something he’s eating or coming into contact with in pasture, he’s in a stall/small paddock combo so lives out and sun exposure but no grass/weeds.
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all of what zevida said.
I had a horse that got grass mumps from about April through October. You could still feel them in the winter, hard small lumps. Three vets at different times checked him but they all said it was nothing to worry about. I hated how big the lumps would get, the throat latch on his bridle would barely fit.
