For a horse owner, there are few sights more welcome than the first signs of spring. As the snow melts away and the pastures begin to turn green, horse owners are glad to see the end of short days, frozen water buckets, and woolly coats. Springtime means longer, warmer days to spend working in the arena or hitting the trails. The season is also an ideal time to catch up on your horse’s healthcare needs.

Equine recurrent uveitis (ERU), also known as moon blindness, is the most common cause of blindness in horses worldwide. It affects 2 to 25 percent of horses globally, with 56 percent of affected horses eventually becoming blind. More than 60 percent of affected horses are unable to return to previous levels of work. ERU is most often characterized by repeated episodes of inflammation of the uveal tract of the eye (the middle layer), involving one or both eyes. A subclinical manifestation, known as insidious uveitis, does not present as outwardly painful episodes, and instead is consistent low grade inflammation (not episodic) that causes cumulative damage to the eye. Cumulative damage caused by ERU can lead to cataracts, glaucoma, and eventually blindness. Although not all horses that experience a single episode of uveitis will develop ERU, they are at risk for disease.

Congenital stationary night blindness (CSNB) is the inability to see in low to no-light conditions (essentially dusk to dawn). It is found in horses with two copies of a specific white spotting pattern mutation known as leopard complex spotting (LP), which is characterized by a symmetrical white pattern centered over the rump with few or no spots of pigment in this white patterned area. This coat pattern is common in Appaloosas, Miniature Horses, Knabstruppers, Norikers, and some other breeds.

Horses undertaking strenuous or prolonged exercise in hot and humid environments may produce heat more quickly than they can lose it, putting them at risk of postexercise exertional heat illness. Early detection of the clinical signs of exertional heat illness and adequate treatments are important to prevent severe hyperthermia and irreversible thermal damage.