Photosensitivity - Arab mare

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karenfordyce57

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I have a 7 year old arab mare with 3 white socks. She gets scabby bits on her legs which vet has said is photosensitivity. Since Sep 08 she has been prescribed 900mg of prednisolene a day. Some times the legs almost clear up then it starts again. She is boxed at night and will be turned out at night time when summer arrives. I am really worried by long term steriod use - my mare has lost a lot of condition and looks like a scarecrow with no muscle tone at all. Any ideas?
 
I am another who is very cautious about using Prednisolone. It does work well and effectively normally, but it is not something I would want to use longterm.

I would look at trying to find the cause of this photosensitivity. Photosensitivity is a symptom, not a cause. Do you have buttercups or St Johns Wart in your field? Could this be the problem? If so, spray for the buttercups and pull the SJW out by the roots.

As an alternative, you could use a barrier cream; something thick like Protocon by Hydrophane.
 
My Arab suffered from photoactive vaculightous (no idea on correct spelling!) about 5 years ago now. It is cause by the horse eatting certain plants like st johns wart and others.
I had put mine out to grass for the summer at my friends yard. he too started with scabs on his white legs. I first thought mud rash but after a couple of weeks treating it ( I had moved him back home so i could wash his legs every day) i got the vet who said it was photoactive vaculightous. medication was steriods high dose to start and a cream with silver in.
The vet came back and clipped the bad, like clusters of scabs off! He had to be sedated!poor pony!! :0(
I then washed his legs every other day in warm water and hibi scrub to try to get a many as the scabs off as poss. it took quite a few months for his legs to clear. he still has slight marks where the bad bit were.
The only way to totally eliminate it is move fields. Its the reaction with (i think) the white blood cells and the sun (Photosynthesising) causing the scabs/bacteria. There isn't much infomation about it either, I've only seem it mentioned once in a horse mag and it was only a couple of paragraphs long.
One of the vets that came out did say his mare had it too.

You could use sun block on her legs, turnout socks. But really you need to stop the cycle of the reaction to beat it, otherwise you will be continually treating the scabs. thats IMO and from first hand experience.
:0)
 
Thanks for that info. I have found it really difficult also to get info. My worry is that my vet is adamant on sticking to the steroid treatment and no topical treatment or washing recommended. My mare's scabs a lot better just on 1 leg apart from hair falling out on other legs. I think that full dose steroids for 6 months has not been beneficial especially now she has lost all muscle tone. How long was your horse on steroids?
 
have you had bloods run for a liver investigation horses get bad photosensitivty if liver damage is going on i dont want to worry you but it could help! my girl got photosensitivty when she had a dieased liver thats how i knew by taking bloods!
 
my grey arab mare suffers from photosensitivity. I have found that eliminating ALFALFA [ also called lucerne] from her diet has helped emormously [dont expect instant results it can take up to 3 months to show the effect] and you need to read lables onthings like nuts, mixes, supplements and balancers. keeping to a plain diet, ie hay, sugarbeet and straights with NAF pink powder as a balancer works for us. Also a fly mask and /or fly sheet during the sunnier months. my arab lives out 24/7 with a field shelter and i find this regime works well for her.
 
Also Alsike clover and buckwheat, I think someone mentioned Alfa before.

Google will throw up loads of links:

This is an excerpt from www.thehorse.com

[Photosensitivity can be caused by plant ingestion. Certain plants contain photo-reactive pigments that are absorbed into the blood when a horse eats the plant. In the presence of ultraviolet light from the sun, these then react in areas of non-pigmented skin, and the horse's skin sunburns. Two main plants are culprits in this situation: St. John's wort (Hypericum perforatum) and buckwheat (Fagopyrum esculentum). Other plants create a photosensitivity response secondary to damage in the liver caused by alkaloids in the plants. Examples of these include Tansy ragwort or groundsels (Senecio spp.), hound's tongue (Cynoglossum spp.), horsebrush (Tetradymia spp.), and alsike clover (Trifolium hybridum). Legume hays have also been implicated in setting up these conditions for skin problems.

Generally, a horse has to consume these plants for a few months before the liver effects are severe enough to allow accumulation of a by-product of plant chlorophyll breakdown in the blood. This compound is called phylloerythrin, and its accumulation in areas of non-pigmented skin causes photosensitivity. Affected areas on the lower limbs are often referred to as scratches, but the process is more correctly known as photoactivated vasculitis.]
 
Hi my lad was on them for a good few months as he was on 48 to start then each week the amount lowered. I had to make holes in carrots and apples so he'd eat them!
I bought the turnout socks (sporta brac ones) but they too slipped down! so i stopped using them!
I did use water resistant sun block on his legs to try and create a barrier but its not the best!
I know my lad had photoactive vasculitis. Is that what your vet has said it is??
My vet gave me a cream which contained silver, i ended up buying a big pot and put lots on. The cream is also prescribed for bad cases of mud rash but you use it sparingly for that.
I used the warm water to help soften the scabs to get them off. I thought the scabs also had bacteria in them which spread. Do you find the scabs are covered in hair, sort of like the hair had grown through the scabs/ or the scabs around the hair?
Can you not change fields or have it sprayed this spring?
But like nuffield said it takes time for it to get out of their system. I brought mine home ( he hadn't had it before or since) in July/ August and i was still treating the scabs in October!!
 
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