Entropion describes eyelid pathology such that the eyelid margin(s) are inverted towards the globe(s). Most typically, the lower eyelids are involved, however upper eyelid entropion may also occur. Similarly, the condition is most commonly bilateral, however unilateral entropion may occur.Primary entropion arises due to a conformational eyelid abnormality and may additionally involve excessive eyelid length and laxity and/or brow-fold redundancy. Primary entropion is common in multiple breeds and may affect juvenile animals (particularly the English Bulldog, Chow Chow & Shar Pei) as well as older animals (particularly the Labrador Retriever & Rottweiler).