Moon Blindness aka Equine Recurrent Uveitis (ERU) in Horses

Update: I recently met Endo the Blind and received an email from someone seeking more information on this subject. Please click on Endo’s photo to learn more about his amazing story and inspirational owner, Morgan.

I’m also adding a question and my response below this original text.


Last summer while at a horse show a friend noticed her horse’s eye was tearing and slightly swollen. It appeared that he had either bumped himself or gotten something in his eye such as hay or sawdust. Several of us looked at the horse, who was otherwise comfortable, and agreed it didn’t appear to be out of the ordinary. The horse quickly recovered and the incident was almost forgotten, until two months later. This time it was the other eye. Again, only slightly but this time a vet was called because the horse didn’t have a history of being clumsy and it seemed a little odd that this was happening again.

The vet thoroughly examined the eye for any scratched or other physical causes but upon finding none explained that it could be uveitis. He left instructions for treatment, including ointments and an anti-inflammatory, and also gave an assignment; document everything you notice. Part of the diagnosis process is the reoccurring part. If it didn’t reoccur then even the second flare-up would be written off as an undiagnosed irritation of the eye. Unfortunately it did happen again. The vet was again called and the horse is now scheduled for a trip to a vet who specializes in treating equine recurrent uveitis.

I have found articles on moon blindness that outline how long the disease has been around (4,500 years, it is one of the earliest documented issues in horses) as well as past and current theories on the causes including; heredity, damp stables, bad feed, and marshy pastures, worms, bacteria, diet, viral infections, injury and stress.

When issues like this happen to a horse you know well it becomes even more personal because it is easier to rule out many of the possible causes. There is no family history, the diet has been checked by analysis, the horse is regularly dewormed and seen by vets, there has been no major trauma and the flare ups have no consistency. The first one happened at a show but another happened during the downtime of winter. Everything has been documented but now she must wait for the final verdict from the specialist.

Have you ever dealt with uveitis in horses? What were the symptoms, the treatments, and the outcome?

Question: “Hello Stacy, I live in Barcelona and would love to one day learn more about your training methods. On your blog, there’s a great Uveitis conversation, and I posted a question, but see it is still pending review.
Not sure if the conversation still comes up, or if you might have more insight, but I by miracle of miracles, just had my second horse diagnosed with uveitis, months apart and I’m totally baffled at how statistically this could be possible – to happen to once person so soon! I’m almost certain it’s something I’ve been feeding – but any further conversation would really help ease my heart right now as well. I’m sure you are tremendously busy, but would really appreciate any more recent insights that might have been discovered. Thanks so much!” Lea


Lea, A very good friend of mine struggled with this with her horse so I learned a lot, hands-on, from helping her.
One thing that we learned from a specialist in Kentucky was that about 80% of the cases are caused  Leptospira.
“In North America, Leptospira interrogansserovar pomona(L. pomona) is the primary pathogen reported to cause leptospirosis in horses. Leptospirosis has been linked to Equine Recurrent Uveitis (ERU) and can also cause abortion and other sporadic health issues.”
From what I understand, it is often transmitted through water.
“Leptospira are typically considered to be enzootic diseases with reservoirs in skunks, foxes, rodents, livestock, and ducks. The organism is present in the urine of these animals, and humans are infected through direct contact or via contaminated water.”

So it is actually very possible that one person could experience more than one episode with this.
I hope that my info helps you continue your research! Things might be different in Barcelona.
Ride with Faith,

Stacy Westfall



  1. Ellie on December 28, 2015 at 3:01 pm

    We have a beautiful mare with ERU. We have controlled inflammation in the eye of these measures: avoiding sun or any light is very important! She is having a very good 95% sunblockin mask on 24/7 – its from I recommend it! Masks are high quality durable and suitable.

    She gets a lot of exellent hay and green dryed alfalfa ‘hay’ but NOT any grain because grain maintains inflammation in the body. We were lucky to found a graifree muesli called Stephans Mühle. It has been good!

    We dont give her any kind of suger – its causes inflammation immediately! We are very strict with this! Also avoid corn, bread and so on

    She also gets C and B and D vitamins, and very important is to get her daily MSM, which is a naturally occurring sulfur. Apple vinegar is also good.

    This is helping – the horse is happy and working well. We are ofcourse closely follow the symptoms and if needed we begin treatment immediately. Now if the eye gets worst, the inflammation goes very quickly over, the eye remains open and the color dont change to gray.

    We are hopeful to get the eye to remain for a long time. We know that it may have to be removed in future but hope that we are able to support the bodys fight against this disease.

    Thank you for this group! Sorry my english 🙂

  2. Sara on August 19, 2015 at 1:05 pm

    My beautiful 15 yr old dun gelding was diagnosed with ERU in his left eye 18 months ago. His most recent flare up in March proved to be very aggressive. I was treating it with bute and steroids 4-6 times per day for many weeks, then cut it down to once a day. Then the eye seemed to be getting worse. I began aggressive treatment once again. Little did I know that an ulcer was developing and so the steroids were making conditions worse. After the vet came out, I decided to have the lavage system placed on him to improve conditions faster and more effectively. After one week of that, we still were not able to save the eye so I made the tough decision to have the eye removed. His eye actually ruptured during the surgery. I bought him a guardian mask to help minimize the flare ups. He wears it 24/7 now. My hope is just that he doesn’t get this awful disease in the other eye. This horse is more like a family pet than anything. I am 31 years old and have had horses since I was 9 but this disease makes me not want to own another horse again.

  3. Ann Baston on August 15, 2015 at 9:17 pm

    My 15 year old appaloosa was diagnosed with uveitis last week. 2 years ago, he was diagnosed with a cataract in one eye. I started keeping a fly mask on all the time, except winter, and watching for any changes in the eye. There has been no swelling, no redness, no discharge. I noticed a shadow in the eye last week, and the vet has said that one eye is blind and he can only see shadows in the other eye. I have been having lessons on the cross country field each week and have been watching his behaviour carefully for signs of change so I was shocked as there have been no indications whatsoever that he can barely see. I have decided that he can see about 20′ out of the good eye. I am now going to monitor to see how quickly he is losing his sight.

  4. Storm on March 16, 2015 at 12:05 am

    I have a mare with ERU. It has been one year and she is probably %50 blind. Anything can be a trigger and the key is to prevent flare ups. I purchased a ‘guardian mask’ from guardian mask company of of Texas and my mare has not had a flare up since June 2014. She wears the mask every day unless it is gloomy out. Light seemed to really bother her. She is a standardbred and this is something that runs in the Standardbreds. I also dewormed just before her eyes initially flared up. Unfortunately it was not a recurrent thing it was a constant uveitis until I purchased the guardian mask. With anti-inflammatory medication and the mask it cleared up within a few days and has not flared up again. However her eye is still degenerating but she appears to see okay. A tad spooky but very functional

  5. Jac on March 14, 2015 at 7:21 pm

    My draft cross was diagnosed with ERU a few weeks after an eye injury. According to my vet, it would/could have been a one time issue except the barn where I was stabling him neglected to ever give him his prescribed medication. Which allowed the problem to become significantly worse. Over the years I had to treat many flare ups. I purchased an extremely expensive fly mask made for horses with the illness, which blocked 95% of the light coming in. I made sure that every barn I stabled him at he had a stall without a window to minimize his exposure to sunlight, which my vet said could aggravate the issue. Eventually I moved him to a barn where the owner/manager refused to adhere to all of his needs, and she put him in a paddock that had a low overhang. He eventually hit his head on the bad side on this very overhang, setting off a flare up that I was never able to get under control. After a month of trying, keeping him stall bound, and countless vet calls, I called my vet and told her I wanted the eye removed. I could stand to keep my horse on bute any longer, nor could I bear to keep him locked up in a stall another day. My vet said that she would come out and double check to confirm that he had loss total use of his eye before she was willing to discuss removal. She confirmed what I had told her, he was completely blind in the “bad eye”, she suggested chemically killing the the eye instead of removing it. This procedure would be less expensive and less invasive than removing it. So, a few days later I loaded him on a trailer and took him to the clinic. The procedure took only a few minutes, and soon we were on our way home. It has been almost 10 years since that day, other than no longer being in pain, nothing about my horse’s demeanor has changed. The draw back to the chemical procedure is it causes the eye to shrink over time, it is now roughly the size of a golf ball. Occasionally, I have to clean out mucus that builds up, as the eye doesn’t drain properly. But thankfully, we have had no issues to date. In hind sight I wish I had never taken him to that first, or last boarding facility due to their poor care; but I am thankful my big guy is still the same amazing competitor and trail horse that he was before the eye went bad.

  6. Lisa on March 14, 2015 at 9:32 am

    My horse was diagnosed 4 years ago with recurrent uveitus. Her eyes will flare up at different times with swelling to where she holds her eyes shut, tearing up. She moves slow usually when it is a bad flareup. My vet said it hurts and gives them a bad headache so he said to give her bute as long as she has any symptoms and also prescribed steroid eye ointment and a dark fly mask. He said eventually she will go blind.

  7. Laurie and Gary Wilts on March 14, 2015 at 6:47 am

    We dealt with this condition for over 5 years. First diagnosed as an acute eye infection. Treated with drops and ointments for over 3 weeks. Appeared to get better. Reoccurred in the fall. Took to a soPecialized vet and he said she must have hit her head. Ordered clot busting med from Ames university vet school. Injected into eyes. Got better. Reoccurred and this time in both eyes and she was totally blind. By trust and heavy lifting from friends we got her back to vet. They injected both eyes and then diagnosed the moon blindness. Option was to take her to Ames for implants in eyes. No guarantees and very expensive. This was my Hollywood Dunnit mare I had worked so hard with. The condition was very painful and kept reoccurring. Finally we were afraid she would hurt herself or somebody she was not used to. She was blind again. We made a very hard decision and had this beautiful well trained and super minded mare down. Just could not see her suffer anymore. It was one of the hardest things we ever had to do. I guess it is becoming more prevalent.
    Please do not knowingly share water sources with strange horses. We do not know where our precious Holly picked up the disease but it is a terrible one
    Laurie wilts.

    • Christina Knote on September 17, 2017 at 1:15 pm

      My heart aches reading this …I just euthanized my mare 2 days ago due to ERU/ulceration where care no longer proved beneficial. 15 years of off and in treatment of ointments and blood serum and pain medication. My beautiful app mare got her wings and is pain free. So unfair.

      • Stacy Westfall on September 18, 2017 at 9:15 am

        I’m so sorry for your loss. This is a subject that I want to write about more in the future…although the available treatments don’t seem to be enough. I wish there was a cure:(

  8. Nicole on March 13, 2015 at 9:18 pm

    I have seen a few appalossa’s come through a rescue I use to volunteer at with moonblindness. One in particular went totally blind unfortunately. They all had weepy eyes with yellowish discharge and seemed bothered by sun or bright lights. There are genetic tests to test for the LP gene to see if the horse is homozygous LP/LP or dominant LP/lp or lp/lp which is the genetic component its believed for Equine recurrent uveitisis

    Also, I know from studying genetics (just recently) that just because an animal has the gene (allele which is a version of the gene) does not mean he/she will develop a condition because the vast majority of the time, components in the environment have to be there too for the disorder to appear. The gene just means “pre-disposed” to getting the condition. Just curious Stacy, what breed is your friend’s horse? Appy? POA? Also, would it by chance have a leopard coat?

  9. Cheryl on March 13, 2015 at 8:53 pm

    I have a 26 y/o POA that went blind 2 years ago, rather rapid progression of Uveitis.

    My vet called another vet that specialized in equine opthamology, and really didn’t have much to add besides ophthalmic antibiotic/steroids. I caught it too late. Noticed behavioral changes first; he was herd boss pushing the other 2 around, never ate with the other 2. One day noticed he was eating with them…and following rather than pushing them off. Made a mental note as was very odd. Weeks later, noticed he bumped into things. Called the vet, rapidly progressed to full blindness in a few months. Years ago I noticed he had depth perception issues with certain colors and going down hill, not sure if it was related. His vision probably worsened in the winter and I missed it, as I work and not home until dark; not spending much time with the horses except the weekends. I could kick myself for not paying better attention.

    He seems happy as long as I let him be a horse and go graze/turn out with the other horses. If they leave him and he can’t hear where they go, he will holler and I’ll go take him to the others. It is not the safest thing, but at least he isn’t penned up and miserable. Doesn’t seem to be in pain. He gets a bit spooky with sounds (hard rain on the shelter, fireworks, etc) but doesn’t run. He doesn’t mind the dogs eating his snacks, seem to like the company.

    My vet said to watch that the others don’t “cull” him. He and my other gelding used to be best buds and the mare the odd one out….now my mare and other gelding are pretty tight with him being alone more. He minds better now if I yell WHOA and will wait patiently for me to get him. I mask daytime, off nights. Don’t shave whiskers to he can feel the ground/corral. The dogs quit herding him and will sit in his corral as he leaves them alone (used to kick at them), so they have noticed the change too.

    As long as he is health and happy, I try to let him be a horse like before but retired. Still sad and wish I had caught it, not sure if the outcome would be different. Healthy in every other way.

  10. cowgirlmichaela on March 13, 2015 at 8:08 pm

    It is said that appaloosas (or horses with appaloosa color) are much more susceptible to ERU than other horses. I have a horse with CSNB, which is also sometimes known as moonblindness but does not progressively get worse.

  11. Ellen on March 13, 2015 at 8:00 pm

    We bought an AQHA “Blue” who had gone undiagnosed with moon blindness. It took him almost falling over a horse napping on the ground to prompt a real examination of the eyes, until that point i do not remember ever seeing excess tearing or swelling. Because the condition itself is chronic but goes through acute stages it can initially be difficult to diagnose. Long story short we caught it too late to stop it from taking his vision but we went through a very intense phase of treatment trying to stave it off, which involved steroid ointment in the eyes 4 -6 times daily. We are lucky in the fact that we through happenstance have 3 horses from a similar line in my barn 2 of which have eye issues varying from almost entirely blind to blind(ish) in one eye. I would definitely buy in to the genetics theory. We still keep the entirely blind guy with our herd of 17 and he does quite well seven years after I initially bought him. Because we slowed the progress of the ERU he had time to adapt – I don’t think I could ever move him to a different stable but his behaviour is quite fascinating and the way he gets around amazing.

  12. Jean Overton on March 13, 2015 at 5:14 pm

    I’ve had two horses with moon blindness and the only option to alleviate the pain was to remove the affected eye. Both horses thrived after that and the illness didn’t affect the other eye. I’ve researched and researched and the one unifying element to cause it was ivermectin use. It’s such an ancient malady that I wonder if dewormer does have anything to do with it. My horses didn’t drink from ponds or dirty water and I believe I have taken excellent care of them all, but this illness persisted.

  13. Lisa Acord on March 13, 2015 at 4:15 pm

    I have a mare that had to have both eyes removed . And she is my best riding horse! We battled uveitis for 4 years. She finally went completely blind a month before her first (and only) baby was born. I trail ride on her . Alone or with wagons and other horses. She will walk, trot, canter. Everything the same except jumping. We can’t jump creeks or anything.
    I have lots of pictures and videos . When she is in the pasture I rigged up what I call walking hobbles. They let her walk at a regular pace, but she can’t trot or run. So she goes all over with no problems. This has worked so far for 2 years. We are getting ready to break and train her baby, but she is still my best horse ever! Don’t give up on your horse! They can still be just as good!

    • STACY VEHRS on June 23, 2021 at 1:56 am

      I know your post is old, but I am hoping you can answer some questions for me. I have a wonderful appy mare that I had already purchased a breeding for. I knew she was slowly losing her vision and hoped to get a baby before she was blind. She has been having the worst flare up in both eyes that she has ever had. I fear she will be completely blind when it is over. I am debating whether to go through with the breeding. Did your foal develop ERU? Many people say although appys are predisposed, there isn’t any evidence that it runs in families. My vet says it is most likely triggered by something in the environment and the foal wouldn’t necessarily have it. Also, how did your blind maiden mare do with a foal?

      • Sam on September 23, 2021 at 2:08 pm

        Hey Stacy! Do you know if you mare is colour tested? If she is and is LP/LP, then look for a stud that is lp/lp. That is the genetic factor that makes them susceptible to ERU. Hopefully that helps

        • Stacy Vehrs on September 23, 2021 at 3:18 pm

          The mare is not LP/LP. She is spotted all over, but the stud is LP/LP. I finally got her inflammation under control. I am using every form of feed supplement known to mankind, and I don’t know which is working. So far so good! I am using Master Jack, MSM, and Equithrive with resveratrol. I tried breeding her, but she did not take. Now I am rethinking letting a mare with severely limited vision having a foal to raise.

  14. Marla McLean on March 13, 2015 at 3:52 pm

    My beautiful appaloosa gelding has ERU and has lost the vision in his right eye. Although we discovered this when he injured the eye by throwing his head into something he couldn’t see, we were able to save his eye. I had to introduce medication directly to his eye socket via an intravenous line that ran through his eyelid and was threaded back along his mane. Twister was raised and trained initially using natural horsemanship methods and so he is extremely sensitive to the leg and has tremendous rider/horse connection. My husband is still riding him in parades such as the Calgary Stampede Parade and at the Internationally reknowned Spruce Meadows for public relations. We also trail ride a lot in the eastern Canadian Rockies. This past year he was exhibiting a lack of confidence on trail but, when encouraged, he trusts his rider. I have found the keys to owning a horse with ERU is to (1) know your horse well enough to know his subtle indicators of pain; wincing; tears; seeking shade; redness; etc. (2) Be kind and treat him immediately with anti-inflamatories until all signs of pain are gone (3) protect his eyes ALWAYS from sun, wind, dust, and dangerous items that could puncture (4) hook him up with a buddy horse to guide him at night and as he loses his sight. There are lots of other things we do but the day will come . . . This is a painful, debilitating affliction for a horse.

  15. Nancy Gidge on March 13, 2015 at 2:50 pm

    My girl was diagnosed about 4.5 years ago with moon blindness; thought it was the end of her 🙁
    I initially had her on Bute but we al know that they cannot be on this for an extended period of time; went natural. Diamond gets supplemented with white willow bark every day and also wears a Guardian mask daily while outside. I am very happy to say and thank God that she has not had another episode since..
    She sometimes may not see totally clear but she does quite fine and no one would know it unless told.
    Keep the faith!

    • Anna on April 9, 2024 at 2:11 pm

      How much White Willow Bark and where did you buy it? How did she end up doing? Did you ever try MSM?

  16. Ellen Brown on March 13, 2015 at 2:27 pm

    I dealt with this several years ago for 4 years on AQHA mare 6-10 years old. About 6 occurrences. Vet check. No scratch. Lepto levels normal. Always the right eye. Swelling, constricted pupil, cotton-candy-like discharge. Treatment for 4-6 weeks. Banamine for inflammation and pain IV or IM. Genacine (antibiotic). Atropine every other day to dilate pupil. Antibiotic/steroid eye ointment twice a day. Also during this 4 year period, I alternated dewormer every 28 days. She could not see out of the eye during these occurrences. We were still able to compete (barrel racing). We have not had a occurrence in over 10 years and non of her offspring have developed the problem. I guess we got lucky. Early detection and aggressive treatment.

  17. Paula on March 13, 2015 at 2:18 pm

    What a timely post. My gelding has this now. He had it two winters ago. The treatment was Banamine and ointment but my vet stained the eye first to check it. It got better and he was fine for over a year. Then it came back last December. Same treatment, same eye. It’s been better, then worse most of the winter. I started treatment again Friday. That eye is clear now, not cloudy but he has lost some vision. Two days ago the other eye started to look a bit funny … now it’s in that eye. Just started putting the ointment in that eye too. He was coping well with one good eye, but now he can’take see well enough to “follow herd rules” to my boss mare’s satisfaction, so I’very put him in a separate pasture with another older gelding. Not sure how it will end yet. Say a prayer for him if you get a chance.

    My vet and my on-line research say the same as you about the causes.

  18. Kate on March 13, 2015 at 2:03 pm

    Yes, If have a horse with ERU. It started about 3 years ago. His sight is slowly going away, but still has vision. He still runs in the pasture and can take him on trail rides.

    I look at his eyes every morning and every evening to see if there is any change and treat if necessary. Thanks to my vet who took the time to teach me what to look for, and available if needed.

    In the pasture I have placed wind chimes of different sound so knows where he is. On the fence line there are solar lights so he does not run into the fence at night. The bugs are not out yet, but it will be sunny today, so he has a fly mask on. I sew additional items onto the fly mask to reduce sun light that reaches the eyes. If he has a bad event, he is treated with medicine and locked in a dark stall for a couple of days.

    Working on different voice commands that can be used from the ground or on the back of the horse. This will come in handy when all of his sight fades away.

  19. Amanda Mason on March 13, 2015 at 1:41 pm

    My gelding has always (since 14months) had issues with tearing and swelling in his eyes. Often the tears are dripping off his chin under his fly mask. (When he was fine that morning when we left.) He is 10 now and we have been told that it is “just allergies”. I initially feared ERU due to severity and frequency. However, my vet said that it is the blindness and pain that are the real tells for ERU. Gail Molsberry is this neck thread worms? I have heard they are hard to get completely rid of. The regimen I have heard is double dose of Ivermectin every day for two weeks. With Vet monitoring as this is a poisonous dose.

  20. Jodie on March 13, 2015 at 1:39 pm

    Sadly appaloosa’s a known for going blind. I know that I put one mare down onceshe lost most of her sight & now her daughter is starting to show signs of vision loss too. I first noticed it in the evening as the sun as setting, the angle of the sun & shadows make it very difficult for the horses to see. We were actually able to ride our mare up until about 95% blindness but that is when we stopped. Sadie was a wonderful mare and it was difficult to finally accept that she was blind.

  21. Lisa on March 13, 2015 at 1:06 pm

    Stacy, thanks for bringing up this very important topic! For anyone dealing with ERU or any other type of eye issue, including blindness, there is a Yahoo group made up of horse owners with blind horses, many of them with ERU. We are a very supportive group with a lot of collective knowledge. ERU can’t be cured, but it can be effectively treated and a horse can live a long, happy, pain-free and productive life with it. We are called “Blind Horses 2” on Yahoo groups.

  22. heccateisis on March 13, 2015 at 12:44 pm

    Yes. I lost a horse to it. It is quite painful and he went blind. He was an appaloosa. It seems to be a common problem with certain appaloosa coat patterns. Although an appaloosa fan, my current horse is not an appaloosa. I just couldn’t go through that again.

  23. Kristyn on March 13, 2015 at 12:21 pm

    I went and looked at a horse to buy and noticed that he had a cloudy eye. Owners hadn’t noticed so they called the vet. At that time I thought it was uveitis. The owner of that horse was a friend of ours, so we decided to see him again, he at that time a couple months later had lost sight in that eye. He was comfortable and everything seemed ok. So we took him to give him a good home. He’s a well bred, nicely trained warmblood so we took a chance. I competed him in the jumper ring that summer, and we had no problems with the jumps. He had a flare up in that blind eye about 2 yrs later, then we battled with ulcers. We decided to take the eye out. We shipped him to a teaching hospital since my vet wouldn’t put a false eye in. He doesn’t have an eye, but a marble behind the eyelid to look like the eye is closed. He took to the surgery well and we still compete at the 1.0m-1.10m jumpers and he is very competitive still and wins most of the classes he’s in. He had a bit of an incident last summer with his only eye. He seemed to be sensitive and didn’t want to open it fully, so we called the vet. No issues with intracoccular pressure and no flare ups! So to this day I am lucky and knock on wood all is good. I take precautions when deworming and vaccines or anything that can comprise the immune system. He is usually treated buth bute a few days before and after to avoid any flare ups

  24. Brian Burks on March 13, 2015 at 11:54 am

    See the article here, and contact Fox Run Equine Center to help with treatment.

  25. Sheary L on March 13, 2015 at 11:19 am

    I don’t think worming with an Ivermec product is the catalyst. Maybe….but I doubt it. This eye issue has been around a lot longer than Ivermec dewormers. This is a nasty thing for a horse to get. Each flare up leaves scar tissue behind, and eventually leads to blindness. I dealt with this quite a few years ago with a mare I had. During that time, I ran across something in the Western Horseman magazine that caught my interest, and I tried what it said, and it did work. A man wrote the article about his little daughter and her horse. Like mine, this girls horse went blind overnight and the horse was freaking out. The vet was called and they tranked the horse to calm him, and tried to treat him, but nothing was working. The vet thought it would be best to put the horse down. The little girl was heart broken and begged her daddy to not put her horse down. This was in MI. I don’t remember anymore if it was upper or lower. The dad postponed putting the horse down and made some phone calls. He contacted one of the universities and explained what was going on, and asked if they would take the horse and experiment with treatments to try to save the gelding for his little girl. If they couldn’t find anything that worked, at least he and his daughter would know that an effort to save the horse was made. The university agreed to take the horse. In the end, they stumbled onto something that worked, although they couldn’t say why. Mega doses of Vit B halted the flare up and cleared it up. The horse was somewhat visually impaired, but still able to be a good riding horse. Now knowing what symptoms to watch for, when the dad and /or daughter saw the horse showing symptoms, he was given huge doses of Vit B, and the flare up would stop and clear up. I opted to try this on my mare. It was easy to see when she had a flare up starting because she would get squinty in the daylight, with tears running. It worked. My method of delivery of the Vit B was Brewer’s Yeast. As soon as I’d see her being squinty, I’d start feeding the Brewer’s Yeast to her, several times a day, and every time, by the next morning, she was fine. I passed this info onto my vet who said he was going to look into it, and remember it for future reference. This is a hereditary thing. So, after my mare started with this, I did some checking up with her former owners who had raised her, and learned her dam had been blind. If you have a horse who develops this, don’t breed it. As with all hereditary things, it’s luck of the draw with a resulting foal. It may or may not have inherited this disease. If your horse has it and is a gelding, no problem. If it’s a stallion, geld him. If a mare, don’t breed her. Not breeding carriers is likely going to be the only or best way to be rid of this disease. It’s sad. I should add that my mare, although completely blind at the time we discovered something was wrong and had the vet out, did regain her vision after treatment. The infection is inside the eyeball, and it can be seen as “marbling” on the eye surface. Antibiotics cleared that up, and as it cleared, her vision gradually returned as well. She was visually impaired though, from scar tissue, but was still ridable.

    • patty fritz on March 14, 2015 at 6:29 pm

      how much vit B I have a Paint gelding that has had flair ups

    • Sally Stults on June 27, 2015 at 1:42 pm

      Hello… hoping someone will share the amount and dosing of Brewer’s Yeast. Thanks very much!

    • Lea Roodt on December 20, 2019 at 3:32 am

      Hello Sheary, its been many years since you wrote your post above, but just wondering, did you ever hear back again from your vet about the use of Vitamin B through brewer’s yeast? I’m desperate to supplement, support and do anything in addition to medication there is to help my horse’s sight from digressing. thanks so much!

  26. BJ Kersey on March 13, 2015 at 11:10 am

    This disease is a hard one to treat when first diagnosed. I bought my gh gelding at 4 years of age. When I went to purchase him I did not notice anything out of the ordinary about his eyes. He is a bay and has dark eyes. They looked perfectly fine to me. However, within two weeks after bringing him home we noticed tearing of his left eye and a slight muscle atrophy. We called the vet out and she diagnosed it as uveitis. Thus we started treatment with Bute, antibiotic salve and atropine in the eye. He did progress very well with this treatment after a few weeks, but again, and again he has had problems with his eye and unfortunately, finally has gone completely blind in his left eye. However…we keep him on a regimen of Aspirease 1/2 scoop daily and the attacks have gotten much better. He has not had a bad attack with it in over 4 years. He has learned to cope well with the blindness in his eye..if you did not know it, you would not believe he was not able to see out of his eye. Riding him, I just have to watch out for him…he has learned to trust me, although when I lead him, he and I prefer he be led from the right side on his good side, and also if you approach him, if you speak and let him know you are there he is fine. He is a wonderful little horse, Poco Bueno bred and I have enjoyed having him in my life, and hope and pray the other eye never has a problem. I keep a close watch on it too. I am thankful that God has allowed me to have him and take care of him. Blessings to all of you who have ever had to deal with this and are dealing with it.

  27. Ashley Black on March 13, 2015 at 11:05 am

    My gelding suffered from ERU for years. His eye would change colors, swell shut, and have puss comig out of it. We were able to manage his pain for a long while, with oral anti-inflammatories daily, and topical eye ointments during flares, but eventually his disease progressed and he lost all vision in the affected eye. With his chronic pain, we ended up taking him to have the eye removed. He has adjusted amazingly to his new, half-blind life. He’s still 100% rideable and is even used as a beginners lesson horse! It’s not a fun experience at all, but horses can definitely come back from it.

  28. jennht85 on March 13, 2015 at 11:02 am

    It is very interesting this would hit my inbox this week. I just put my 22 year old OTTB down Monday afternoon due to complications with ERU and heaves. A few years ago my horse’s eye was swollen and red but after examination at home we believed he bumped it and left it alone. The next day, it was swollen shut and my horse was visibly suffering. We hauled him to the vet where they determined he had ulcerated his eye. It was a nightmare to get under control, doctoring his eye 6x a day and finally resulting to flushing his eye with blood serum to help. After a costly bill and many hours at home caring for him he recovered fully, besides a tiny pin head of a blind spot in his eye.

    I am very thankful he came through that okay and retained his sight. We enjoyed a few more riding years before he started losing his sight and developed heaves. His eye did flareup once or twice a year, but with early treatment and a good history with my vet, we were able to keep it under control and a lot less painful for him in the end. I had to make the very tough call coming out of winter this year as he developed pneumonia due to heaves and lost more of his mobility due to age, lameness, and blindness to euthanize him. I believe all if it is related, the heaves and ERU, and both conditions were just too much on his elderly body to handle and recover fully. He’s been retired the last two years enjoying life as the babysitter and herd sire for my small group.

    I can tell you with 100% certainty that weather/season changes played a huge role in flare ups with ERU. Changing from fall to winter, usually during the first hard cold snap, was when we were prepping for a problem. And again, as winter changes to spring, I always kept a close eye on him. This has been our personal battle the last couple of years. I did have him on prevacox the last 2 years almost daily to help with his inflammation and that seemed to keep his flareups less severe and his pain under control without the worrisome effects of long term bute usage. I also started using a blanket on him in the cold weather when he first started flaring up with ERU and that seemed to help a bunch. Any way to help his body maintain energy to fight the inflammation seemed to prove beneficial in the long run.

  29. Gail Molsberry on March 13, 2015 at 10:55 am

    Last fall, I had a twelve year old POA gelding who was diagnosed with moonblindness. It started out with slight tearing and running in one eye and within a few weeks we started to notice he would stumble a lot and be very uncertain where to put his feet. He then got spooky and would have to touch your arm when you led him. After consulting with the Western College of Veterinary Medicine in Saskatoon, Saskatchewan, he was diagnosed with moonblindness. The vet who specialized in this disease told us that the disease was actually caused by a small worm in the neck muscles of horses and when the horse is dewormed the dead worms are carried through the blood and lodge near the back of the eye. It is most prevalent in the appaloosa breed (depending on color pigments) and often in the throughbred breed. This is what she found in her studies. But we have since discovered that in our particular case, our geldings sire and two siblings to date have also contracted the disease. All of them at a older age in life. So, I feel it would be safe to say in this particular case it is indeed genetic. This is a terrible disease that seperates wonderful horses from those who love them, as there is no cure and no real treatment and no way to stop the progression of the disease.

  30. Jill Lorenz on March 13, 2015 at 10:51 am

    I have an older Paint with uveitis. First noticed his eye was foggy so called the vet who prescribed ointment. After additional flare ups, one after the other, went with daily aspirin regimen for inflammation. It flares up every now and then and we treat with the ointment for several days. He can go one week between flare-ups or a year – no rhyme or reason. Unfortunately, he is going blind and has developed cataracts in both eyes. We also keep a fly mask on during the summer as his eyes are very sensitive to the sun now.

  31. Lynn Shoner on March 13, 2015 at 10:48 am

    I’m experiencing similar symptoms and my vet is coming next week….

  32. amy heil on March 13, 2015 at 10:46 am

    I have an Arabian mare thats totally blind from this. My parents purchased her when she was 1 yr old. She was an addition to our ranch yrs ago. She got sick with uveitis from lepto a bacteria in dirty drinking water probably from a old contaminated trough of creek, puddle who actually knows. She was around 10ish. Shes now 26 blind as a bat living the retirement lifestyle. Happy fat sassy lil arab. Still trots around throwing her head everywhere but happy and full of spunk. As she was going blind it never affected her she was an amazing animal my sons first horse he is now 13. My aunts confidence booster learning to ride again after 40 plus years. And my best horse ever. I still can ride her to this day. She blind as a bat but trustworthy and honest. She even is gonna joining to be used as a therapy horse for kids in the spring. After many flares, a wonderful vet Teresa Crocker here in northern California my old blind lil arab is doing great. We keep her fly masked most of the day to protect her eyes. Ya its been alot of work but good horse like people are hard to come by. I never gave up on her and she never gave up on us. I love my lil blind as a bat fat sassy arab. Princess Paula aka shasta. Best of luck there is no cure. At least as of yet.

  33. Pam Ramsey on March 13, 2015 at 10:45 am

    I also had a mare with Uveitis, and used ointments and drops from the vet. We tried for months to get it to go away. It did for about two months and then came back with a vengeance. It was tough as the mare was starting to walk into fences and the barn door. She was a mare that anyone could ride with a lead rope and halter.We finally had to put her down. She was always well cared for and was born on the home place and never left the family.

  34. madison on March 13, 2015 at 10:44 am

    My Twh gelding has this and has gone completely blind in his left eye and just this week it has moved to his right eye and starting to loose vision in it he was first diagnosed with this three years ago it is very devastating and needs to be treated emediatly and hit it hard with treatment

  35. cindy on March 13, 2015 at 10:18 am

    I have a horse that’s been doing that for 3 years ! Vet appointment Wednesday! And his behavior has changed to a spooky horse I used to ride in a halter was so good does you’re horse act like that? Hope all goes better

  36. Michelle A Wolfe-Harris on March 13, 2015 at 10:07 am

    My OTTB mare has moon blindness in her left eye. It doesn’t always affect her actually pretty mild case for her. When it flares up her eye gets teary she is little stumbly but because we have a great bond when it flares I have trained her to respond to left right stop cues. She trusts me and I trust her together we will get through this. Trihist kind of helped keep her allergies in check to where it didn’t flare as often. The flare ups usually happen when its really windy or really dusty

  37. Jackie on March 13, 2015 at 10:06 am

    You need to add “Appaloosa” to your list of causes. I treated my guy 4 times a day, with 4 different meds for months (no easy task when you work days full time) and he still lost his vision in that eye. He has adjusted, though he has become super-dependent on one of his pasturemates. When I notice a flare-up or if he looks like he’s experiencing discomfort in that eye I give him some banamine which helps. He’s 34 years old this year and is retired, but I would never dream of putting him down as long as his quality of life is good, we just take it a day at a time and are blessed to still have him.

  38. Rene on March 13, 2015 at 10:04 am

    I spoke with my vet about it and he says the most common factor he has discovered is it happened right after someone wormed with invermectin. I met a woman a few yrs. back named April Battles who has had great luck in reversing it with the use of natural cellular defense. It is a product made with Zolite that has been processed and tested to be safe to use in the eye. She also recommends cranial sacral sessions to remove the pressure from the eye. I hope this helps someone out there who is dealing with this and would like to try a non traditional cure when there is no hope!

    • Jean Overton on March 13, 2015 at 5:32 pm

      I wish I’d heard of this sooner.

    • Hillary on March 14, 2015 at 1:27 pm

      Humm that is interesting Rene. I had a dog OD on Ivermectin once. she went blind and was going nuts. i took her to the vet and they pumped her full of fluids..she came out of it fine..BUT it would make sense that maybe the ivermectin is causing damage to parts of the eye!

  39. Karen bockus on March 13, 2015 at 9:35 am

    I spent 5 months doctoring my horse numerous times a day for this ugly disease. I had to euthanize my horse in the end because he went totally blind and was either going to kill himself with something or me. It’s a painful, horrible sickness. I would never put a horse through the pain againI
    . I believe he got Leptospirosis as a result of drinking from ponds and puddles. This horse was not cared for properly and had to fend for himself before I got him so he would drink from puddles rather than come to the barn for fresh water. The two horses I have now have always been well cared for and will walk all the way from the back pasture to drink from the fresh clean trough. I believe how an animal is cared for makes a difference in behaviours. My other two are very clean, this other horse was dirty. Also if you ever have raccoons any where near your barn it’s a perfect storm for Leptospirosis. So vets are now suggesting using the dog vaccination, who knows. Better to keep a clean barn area and not attract the vermin.

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