Hallo there! Another day in the world of Tony here (just waiting for the Monday to come so I have all my people paying attention to me again). This weekend, watching the vets prepare another edition of our monthly newsletter, The Naughty Pony, I was amazed at what Dr. King had to share about a new eye medication called Equitrx Corneal Repair drops (from Bayer). I mostly stole this week’s blog from the newsletter, because I think as many people as possible need to know why they need to call us quickly when their horse’s eye becomes painful.
The vets at Springhill Equine have experienced recent success in treating ‘fresh’ corneal ulcers, thanks to a new medication. Corneal ulcers – defects or scratches on the outermost surface of your horse’s eye, are a serious problem for you and your horse. The new medication is for ulcers recognized in the first 24 hours, so we encourage you more than ever to call us IMMEDIATELY if you notice your horse has a painful eye.
Dr. King first learned about the medication, called Equitrx Corneal Repair drops, when a Bayer representative presented at a University of Florida Equine Club meeting (UF SCAAEP). She has subsequently prescribed the medication to appropriate cases with great success. Corneal ulcers are a particularly frustrating and potentially expensive problem for horse owners in Florida. The cornea, the outermost clear surface of the eye, not only is part of the sphere that keeps the eye inflated, but is the window to the eye. It contains no blood vessels and no water, thanks to special water pumps inside corneal cells – and this is how this thin layer stays so clear. An ulcer is a disruption in this outer surface – from a bump, poke (hay and grass heads are common culprits), or who knows what. Sometimes the defect heals quickly over in the face of infection, and what is called a ‘stromal abscess’ results.
The cornea itself is made up of three layers – akin to a hamburger (meat between two buns). A corneal ulcer disrupts some portion of the top bun and the meat, but can erode down and or/through the bottom bun. A stromal abscess is in the meat with both buns intact. It can rupture into the eye, or out. The scariest part is that the bottom bun is only 2 CELLS thick! The corneal layers are extremely sensitive to pain – which is why if you try to poke a horse in the eye, he reflexively shuts it. This ‘corneal reflex’ is one of the last reflexes to leave a horse when it dies, and can be used by veterinary staff to measure depth or level of anesthesia.
If your horse suddenly has one painful eye (squinting, eyelid drooping, tearing), a corneal ulcer is suspected until proven otherwise. If we see your horse, we will look in the eye, and can often see the defect in the surface, and in later stages blood vessels and/or surrounding edema. Blood vessels and edema obscure the window, making it hard for your horse to see. We will stain your horse’s eye with florescein, a bright green dye, which binds to the meat of the cornea. The amount of stain will show us how big and where the ulcer is. It can also help differentiate a corneal ulcer from a stromal abscess. Florescein does not bind to either bun, so in the worst cases, there is no stain in the middle of the ulcer (bottom bun), and a ring of green where the meat is exposed. These are medical emergencies and generally are treated surgically, which is usually close to and potentially significantly more than $5,000 by the time the ulcer has healed (usually weeks to months). Appropriate medical treatment for the average ulcer can easily reach $700-$1200 in 1-2 weeks of treatment, if hospitalization is elected (and strongly recommended) at Springhill Equine or a referral facility.
The first medication used to treat corneal ulcers is an antibiotic ointment applied directly to the affected eye. This allows the ulcer to heal free of infection, which will constantly and continuously work against and erode the healing cornea. Another significant potential for infection comes from fungi, which are unfortunately abundant in Florida! Fungal infection results in a ‘melting ulcer’ – where the cornea literally appears to be melting away (droplet-like) from the site. These are extremely difficult to deal with, aggressive antifungal treatment is necessary (eg, hourly, 24/7) to save the eye, otherwise surgical treatment may be required (removing the eye as the battle fails).
Atropine is also used as a topical eye ointment, to dilate the eye keeping it more comfortable. Banamine is used as well to keep the horse comfortable (it appears to work better than bute). A variety of other topical medications can be added into the regimine based on severity. However, without corneal healing, these treatments are for naught. This new product, which contains hyaluronic acid (a viscous fluid that we inject into joints), provides a scaffold over which the healing corneal cells can move. Dr. King has seen healing within 24 hours in 4 out of 5 horses she has prescribed it to (the 5th was particularly large/severe and required several weeks to heal). These cases all fit the appropriate criteria for the company recommends for treatment (eg, they were certain to have occurred in the last 12-24 hours).
I am convinced, as is the rest of Springhill Equine, that this new product holds a great deal of promise for horses attended within 24 hours of injury. We recommend, now more than ever, that you please call us IMMEDIATELY if you notice your horse has a painful eye, to save you and your horse a potentially long and painful process! Thanks for reading, and may your litter box be clean and your food bowl full!