Freedom has a kind eye, which reflects his gentle nature. Over the 16 years that I’ve owned him, however, his left eye has changed. Freedom started to lose pigment in the iris of his left eye a few years ago. It came on gradually until now it’s a quite a large spot, which is almost translucent.

Luckily, for Freedom, this change has not impacted his comfort or his vision. In fact, it’s fairly common among older horses. Speaking about it to my vet, I was told it could also be a by-product of his racing years, if he was hit in the eye by dirt (although the eye was fully brown until a few years ago). There has never been any tearing, infection or light sensitivity.

Changes in your horse’s eye can, however, be quite serious and should not be taken lightly. Whenever you notice a problem with your horse’s eye — tearing, infection, pain — contact your veterinarian ASAP as early intervention can often prevent long term damage.

One of the most common problem is a bacterial infection that occurs when something gets into your horse’s eye and scratches the cornea. This is usually treated with a non-steroidal ointment. Just be forewarned that it doesn’t take your horse long to figure out that they don’t like the treatment!

Equine recurrent uveitis (ERU) is the leading cause of blindness in horses. Also called “Moon Blindness”, — not because the cornea can turn cloudy blue or white like a moon (my assumption) but because early observers thought its repeated occurances were like phases of the moon.

ERU is an auto-immune disease which causes progressive and recurring condition of inflammation within the eye. ERU affects about 8% of horses but Appaloosas, which have a genetic predisposition to the disease, are 8.3 times more likely to develop uveitas than other breeds, frequently have a persistent form of the disease, and are nearly four times more likely to become blind.

A definitive inciting cause for uveitis has not yet been determined; however, the inflammation is widely thought to be due to an immune-mediated reaction in genetically susceptible animals. Symptoms include: squinting, holding the eye shut in response to pain, light sensitivity, tearing and a bluish or cloudy appearance of the cornea.

Horses diagnosed with this disease are typically managed with topical anti-inflammatory drugs during acute flare-ups of disease to reduce pain. However, some horses end up needing their eye removed. This was the case for one of the horses in our hunt club, who is much more comfortable since the surgery. In fact, she is still out there in the field jumping fences.

In every case where you fear a problem with your horse’s eyes, always call the vet, put a fly mask on to protect the eye, and if feasible, keep your horse in its stall until the vet arrives.