Mud fever type scabs?

[Nannon]

My ex racer had these scabs on his legs when I bought him - I assumed that they were mud fever and treated them as such and they cleared up after a while - used sudocreme to start with and it got worse, then tried msm abd washing with hibiscrub and then just washing and getting scabs off which seemed to work.
Past couple of weeks I've noticed them coming back, despite no mud and not having had wet legs... Farrier seems to think it could be a UV sensitivity or sensitive skin? He only gets it on his white legs and it ranges from little tiny scabs to ones the size of my thumbnail.
Just wondering if anyone has any idea what it could be, and if there's any way I can stop it happening or clear it up?

 

[Orchardbeck]

Mine gets this in the summer only, but every summer without fail. I believed it to be some sort of light photosensitivity, which apparently comes from liver damage (from say ragwort poisoning, or other toxins).

However, I had her blood tested after a colic episode for liver damage in the winter and there was no sign of any, even given her age (23) so whilst reassuring, does not explain the scabs/weeping, although this could be from some sort of photosensitivity unrelated to the liver - I'm no veterinary expert though!

I try not to touch it too much, if I brush her legs the longer hair comes off in clumps and patches and the skin is quite scurfy but the hair tends to grow back. She has four white socks up to the knees and a large white blaze, almost to the point of being a white face so I have to put factor 50 on her nose if it is a sunny day. When she was younger it turned in to mud fever one year, so I would keep an eye on it for any swelling.

If anyone else has any experience of this I'd like to hear about it - I have heard it referred to as 'cannon crud', or also a product of mite infestation, but it is too coincidental that it occurs as soon as the sun shines!

 

[Nannon]

Sounds similar! I knew nothing about it when I got him, they said he had been turned out for a while so I just assumed it was mud fever but this winter there has been nothing wrong with his legs - just literally the last month or so! I have the same with the hair coming out and really scurfy - he's a little scurfy all over at the moment but his legs are much worse