Corneal endothelial decompensation represents a progressive loss of corneal endothelial cell function & density and results in slowly progressive corneal edema. Corneal endothelial cells do not regenerate & have only a limited ability to compensate. Clinically, this disease presents as progressive, avascular, corneal edema, marked by blue/grey discoloration & thickening. Changes typically begin within the superio-temporal corneal quadrant. The disease is bilateral though not always symmetrical. Initially, changes do not result in significant visual disturbance or discomfort, however with progression, a cycle of painful bullous &/or ulcerative keratopathy may develop. Commonly affected breeds include the Boston Terrier, the Dachshund, Chihuahua & the Miniature Poodle.