An eye ulcer is a wound on the front of the eye; they are very painful and can develop for many different reasons.
Ulcers often appear suddenly and get rapidly worse. However, eyes heal quickly so with vet treatment an ulcer is likely to heal within a few days (unless complications develop).
Leaving an ulcer without veterinary treatment can result in loss of an eye.
Book an appointment with your vet ASAP if you notice anything wrong with your dog’s eyes – they are too important to leave to chance.