UV sensitivity

[ycbm]

Ludo, half appaloosa (so night blindness not possible genetically, I think, as it needs both parents) has suddenly developed quite a strong reaction to UV light. So much so that unless he is masked when turned out, he stands nodding maniacally, even on a cloudy day. It's also affecting him ridden, so from now on he will be ridden in a mask or in goggles.

Obviously I've caught this very early, he hasn't even got sore eyes as far as I can tell.

Does anyone else have a horse like this? Is it likely to progress? I can find plenty online about uveitis but he doesn't have uveitis (yet?), just this mad head nod turned out and occasional ear shake when ridden. Which stop completely when masked at 70% UV reduction.

I've been watching for this because of his breeding and age, but also wondering if there are other triggers. If does seem in humans there might be a gut biome link.


All information and suggestions welcome.
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[JumpTheMoon1]

What does your vet say about this ?

 

[ycbm]

What does your vet say about this ?

I'm waiting for him to reply to my email.

Thanks for your invaluable input

 

[Highmileagecob]

Nothing useful to add, but I wonder if you have spotted a cause of headshaking that hasn't been covered? Is Ludo blue or albino eyed? That level of sensitivity may indicate some macular deficiency - but no idea whether horses even suffer from macular degeneration....
Masking his eyes sounds like a good plan.

 

[SO1]

You have recently moved could he had developed an allergy to something in the local area that he is not exposed to in your old area. I presume it is only outside and does not happen when stabled or in the evenings so hence you think based on the light.

 

[nutjob]

My headshaker was similar to this. He had to be turned out in a dark fly mask which had a nose cover. It never progressed to any sort of problem with his eyes. For most of his life a nose net was enough when he was ridden but later on he did need a mask over his eyes as well. There were probably other factors involved as it was seasonal, but the light level was definitely one of them. He was worse in the evening if the sun was still bright but low in the sky and a change of light level would really affect him like if he came out of a woodland into sunshine.

He was also reactive to any flying insects around his head. I had his eyes checked by a vet a couple of times during his life time but they couldn't find anything visibly wrong.

Nerve blocking showed that mine had trigeminal neuralgia but I have read recently that they don't do this much now as it's an unreliable test. As a positive mine lived to 16 and was pts for totally unrelated issues.

 

[ycbm]

You have recently moved could he had developed an allergy to something in the local area that he is not exposed to in your old area. I presume it is only outside and does not happen when stabled or in the evenings so hence you think based on the light.

I believe UV because he does it whenever the sun is up (not necessarily shining) and stops when the UV is blocked, either by a roof or a mask.

Earlier in the year he shook his head in a couple of specific areas of wood, so I was pretty sure that was a new pollen allergy.
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[ycbm]

Nothing useful to add, but I wonder if you have spotted a cause of headshaking that hasn't been covered? Is Ludo blue or albino eyed? That level of sensitivity may indicate some macular deficiency - but no idea whether horses even suffer from macular degeneration....
Masking his eyes sounds like a good plan.

He's got white sclera and pale skin colour typical of appaloosas. They eye sensitivity is a known thing in appies.
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[LEC]

I had one who went full weepy eyes and needing steroids to worrying we were going to lose the eye. I have found a lot of UV sensitivity is related to allergy’s and immunity. I find the same thing a bit with legs getting scabby in UV.

We have had the Equivizor for a few years for riding out but this year were able to drop the fly mask down a level from the full guardian one we had and haven’t used the Equivizor.

We have had a lot of issues with this horse with ulcers, looking terrible after anti Bs, and being allergic but we have solved a lot of it through gut balancers and very careful management. She lives permanently on probiotics now and looks amazing. I do think the ulcer sensitivity is all part of the same issue but took longer to appear.

 

[nutjob]

He's got white sclera

Interesting, no idea if it's relevant but mine had white sclera, an ISH not an appi though.

I have found a lot of UV sensitivity is related to allergy’s and immunity.

Also, interesting, mine as well. Allergic to multiple things and had a terrible bout of lymphangitis for no apparent reason.

@ycbm I also had one years ago which developed a very odd type of headshaking and skin problems linked to uv sensitivity when he was older and already retired. This was linked to a liver problem and resolved when his liver enzymes went back to normal.

 

[ycbm]

Interesting, no idea if it's relevant but mine had white sclera, an ISH not an appi though.

Also, interesting, mine as well. Allergic to multiple things and had a terrible bout of lymphangitis for no apparent reason.

@ycbm I also had one years ago which developed a very odd type of headshaking and skin problems linked to uv sensitivity when he was older and already retired. This was linked to a liver problem and resolved when his liver enzymes went back to normal.

Thank you for that thought, I might have his liver enzymes tested. None of the rest of him is photosensitive, and he's mostly white and very thin coated, but who knows.
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[paddy555]

I would consider a referral to an equine ophthalmologist to see if anything is going on

 

[RamblingRosa]

My few spot Appaloosa head shakes due to sunlight, she wears a fly mask all summer and sometimes in winter. Her eyes are fine.

 

[Ossy2]

Are you sure it’s a UV thing? This is exactly the initial symptoms of my headshaker, hers was faulty facial nerves below the eye, nothing wrong with the eyes themselves.

 

[Sossigpoker]

This is pretty standard headshaking I'm afraid. Most owners don't seem to know what starts the symptoms as often they appear suddenly. Bright light is a common trigger.
Oddly enough, my mainly pollen triggered head shaker has pretty much stopped it since he's had his hocks medicated and back treated. I don't know if it's a coincidence but the difference is remarkable. I can now hack him on routes with huge hedges either side of the track - he used to really suffer there. Now he barely snorts.
So I wonder if it could be anything like pain in the back or neck that's triggering the trigeminal nerve?

 

[ponynutz]

Does it continue in winter? Or do you not know? Because UV index isn't the same thing as the sun being up. If it does happen all year round (although would probably get worse in summer) then, yes, UV is probably the trigger.

Other than that I have nothing else useful to add as have never been in this situation, sorry. Hope you get it sorted.

 

[Caol Ila]

Could be trigeminal nerve headshaking. Light can cause it ("photic headshaking"), and fly masks help if that is the case. This is a pretty decent article on it.

https://practicalhorsemanmag.com/health-archive/get-a-grip-on-headshaking-syndrome/

 

[PurBee]

Ryegrass contains photosensitising agents, (PSA) aswell as a few other plants and drugs horses sometimes receive.

I discovered this about ryegrass when my gelding ages ago flared up with huge wheals all over his body, after changing a haylage brand.
He’s grey, with some white skin, mainly black skin. His white skinned areas became very swollen and weepy. Yet, a white skinned horse can become very affected by photosensitising agents due to just skin colour, a black skinned horse exibiting this likely has a liver issue.
(He has a history of a stint out at loan gone wrong where i suspect possible liver issue occurred, ragwort most likely - it was this episode that made me aware his liver could have some damage, but below the threshold that shows up on bloodwork results. The liver can be half dead due to ragwort damage and show average enzymes - its incredibly resilient functioning organ, and still operates like a full liver, just not as effeciently/fast as a fully healthy liver, hence not clearing toxins or photosensitising agents so fast out of the blood from feed )
I cant recall the exact biological details without a refresh research stint, but if the liver is impaired it cant filter and shunt so well the bioluminescing agents from the ryegrass feed so they leach out much more into the blood stream affecting even dark skin, and they have ‘allergy’ type symptoms like hives/puffy eyes/ runny eyes/ uv intolerance preferring shade.

Yet a white skinned horse is far more susceptible as the photosensitising agents still circulate in the blood somewhat just due to the normal feed absorption pathways and hence symptoms easily appear because their white skin has suddenly become ‘very fair skinned’ due to the ryegrass PSA’s.
Pigmented darker skin naturally protects UV, than lighter skin. My full black skinned mare was A-OK during this feed change.

Aside from the hives that weeped orangey sticky fluid - he kept himself in the shade, was head-shaky. He was around 5 when this happened - he had not been on mostly ryegrass haylage before this, always a 50/50 mix ryegrass - so didnt think the switch to a higher ryegrass % mix, predominant ryegrass, would make much difference. Over 3 weeks the hives started neck then covered his body, starting exactly when the feed changed, so i knew it was the feed, just couldnt fathom what was so aggravating about ryegrass and a few other known safe grasses.
Deeper research lead me to the photosensitising luminescent nature of the structure within ryegrass, and him having some fair skin but not enough to warrant this reaction, unveiled brought to light a liver issue that must be minimal as he’s never been sick except this episode.

I stopped the full ryegrass, went onto half/half ryegrass, and 2-3 weeks the symptoms cleared, keeping him in the shade/barn area/under big trees.

Again, rusty memory failing me on details but i recall tetraploid variety of ryegrass to be more photosensitising than diploid. Tetraploid has higher sugars than diploid, often fed to cows, but has made tracks into equine feed market as its a high yielding weighty crop, but on sugar levels alone isnt useful for most horses.
The sugars and discovering the photosensitisation nature of ryegrass is why im really not keen on this grass as feed for horses, but its become so popular in hay mixes, and certainly haylage market.

It makes me wonder if its the PSA’s in ryegrass causing the rising reported equine allergy symptoms, and not pollen as mostly suspected.
PSA’s + UV light = allergy symptoms of all the varying presentations depending on the individual biology/skin type of the horse.

Tetracycline antibiotics also cause photosensitivity - i was on this myself for a long stint of 6 months in younger years, im fair-haired, freckle fair skin, and spent the time in sunglasses, and covered up - my skin suddenly blistered at the minimalist exposure to the sun. The effects lasted a long while for months/year after coming off the medication. It seemed to remain in my system for an unusually long time.

I just remembered that aloe vera gel is photosensitising too. A rep for a major producer i was involved with briefly, shared a huge amount of aloe vera info, and its not wise to put it on skin and then be out in the sun. Whether taken orally if it has the same photosensitising effects, i dont know - worth considering, as everything eaten ends up in the blood initially then filtered over hours by the liver/kidneys etc - but certainly topical skin application should be avoided while exposed to sunlight. It ironic really as its touted to be great for healing sunburnt skin, which it is, so people use it on horses sunburnt noses - but it could be making the sunburn worse if horse is then turned out into UV strong light again with an aloe vera nose.

Thought id mention these aspects as youve changed yards/grazing so Ludo could be more exposed to these that he may have had before, just not this degree of intake, and its tipped his system over the edge. I know youve moved now (congrats!) - is it more sunnier/less clouds where you are now compared to previous home?

 

[PurBee]

https://aaep.org/issue/sunburn-photosensitivity

 

[Britestar]

A friends horse developed photosensitive headshaking after being ridden, and there was a lightening strike within 100yrds.
He was treated with steroids as I recall, and ridden/ turned out with a mask.
Hes nearly 30 now, but I'm unsure if its still a problem.

 

[ycbm]

I would consider a referral to an equine ophthalmologist to see if anything is going on

I can't think why i would do that Paddy. He's a known breed for UV sensitivity. He's a prime age to start head shaking, which my vet tells me is 7/8. Head shaking is extremely common and notoriously difficult to cure (not to manage, that's often easy enough, but to cure). He has no problem seeing and his eyes themselves are showing no sign of any issues. He stops all odd behaviour in a UV mask sold for £18 in the shop on site.

I can't imagine why my vet (who I don't think will be interested in a call out unless I insist on one) would refer him to an opthalmologist.
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[ycbm]

Does it continue in winter? Or do you not know? Because UV index isn't the same thing as the sun being up. If it does happen all year round (although would probably get worse in summer) then, yes, UV is probably the trigger.

Other than that I have nothing else useful to add as have never been in this situation, sorry. Hope you get it sorted.

I don't know yet it's only just started.
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[ycbm]

Are you sure it’s a UV thing? This is exactly the initial symptoms of my headshaker, hers was faulty facial nerves below the eye, nothing wrong with the eyes themselves.

What age did yours start?
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[ycbm]

is it more sunnier/less clouds where you are now compared to previous home?

We're only a few miles away PB, but also a lot lower and the UV is much lower down here. Up at the farm all red things bleached pink really quickly and the rest followed.

I will ask what variety of rye they are growing for the haylage thank you. I could swap him onto hay (cut elsewhere) for a trial but I don't like feeding it dry and soaking would be an issue.
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[scats]

I have a sunlight headshaker. She is worse on really bright days and worse under saddle, particularly when you ride into the direction of the sun. Hers manifests itself as almost a weird twitch.

 

[Sossigpoker]

Oh and if he's on rye grass , he needs to come off it or at least needs it reduced dramatically. Growing grass and especially rye grass is high in potassium,.which then unbalances sodium and magnesium
I'd remove him from grass and add two table spoons of table salt per day to his feed and a magnesium supplement.

 

[ycbm]

He won't eat salt or magnesium in his feed since he moved. I'd forgotten that, good thought thank you. I'll try to reintroduce them but he leaves his bucket feed anyway even when his haylage runs out.

He's eating very little fresh ryegrass, but a lot of haylage.
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[milliepops]

My photic headshaker is normal on dull days, it's only bright sunlight that triggers her. It started after a bee stung her inside her nostril. She developed a huge reaction and also got a droopy eyelid so assume some nerves were damaged. The eyelid improved hugely but the headshaking remains 10+ years on. The equilibrium mesh riding mask was enough for mine to be comfortable.

 

[Esmae]

I had a half appaloosa that developed night blindness.

 

[Sossigpoker]

He won't eat salt or magnesium in his feed since he moved. I'd forgotten that, good thought thank you. I'll try to reintroduce them but he leaves his bucket feed anyway even when his haylage runs out.

He's eating very little fresh ryegrass, but a lot of haylage.
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Try a different feed , preferably something that you soak , like Allen and Page feeds. Then add the salt first , very gradually. You could also buy some spearmint and mix that in for an extra appetiser.
Mine isn't keen on chaff based feeds or chaff in general but loves his Fast Fibre and Cool and Collected and happily eats about a table spoon of salt in each feed.
Adding a balancer (Saracen Lite something) seems to have also coincided with the almost stopping of head shaking , as well as his hocks being treated , so it is possible it has further addressed a mineral imbalance. Mine is on an almost bare paddock with soaked hay as he does so much better with very limited grass