Research is ongoing to learn more about this frustrating cause of blindness in horses.

Question:

I would like to know what research and/or advances are being made in treating/preventing Equine Recurrent Uveitis.

Answer:

Equine Recurrent Uveitis is the most common cause of blindness in horses and one of the most frustrating eye conditions to treat. ERU is believed to be an auto-immune disease, which means the horse’s own immune system inappropriately attacks the delicate tissues inside the eye (instead of attacking foreign invaders, like bacteria and viruses). The great mystery of ERU is how and why the immune system gets confused and starts to attack the inside of the eye. Some researchers believe that infection with Leptospirosis starts the process, while others believe that any type of infection within the body or trauma to the eye can initiate ERU. Regardless of the inciting cause, however, the end result is the same: self-perpetuation inflammation inside the eye that can lead to devastating intraocular disease and permanent vision loss.

The mainstay of controlling ERU outbreaks has always been topical and systemic anti-inflammatory drugs (i.e. Banamine), but new technology has become available in the past few years. Cyclosporine A (CSA) is a very effective drug and modulating the activity of the immune system, and North Carolina State University has developed a dissolvable plastic disc impregnated with CSA that can be surgically implanted underneath the sclera (the white of the eye). The disc slowly dissolves over two to three years, allowing the CSA to reach the inside of the eye and tell the immune system to stop attacking the inside of the eye. The long-term success rates with decreasing the duration, severity and frequency of ERU episodes (and thus their blinding side effects) are excellent. A veterinary ophthalmologist can tell you if your horse is a candidate for this type of implant.

Other CSA-type drugs are also under investigation, but it’s too soon to tell if they will be as successful as the CSA implants in controlling ERU long term. ERU is a frustrating disease, and more equine research is needed about the cause so that we can design more effective treatments!

– Dr. Amber Labelle, member of the American Association of Equine Practitioners

You can help support equine research that helps save the lives of our horses. See what the American Quarter Horse Foundation is doing to help keep our horses healthy.