Dogs can lose their vision as a result of an illness or disease, genetics, or serious injury. Only your veterinarian can diagnose these issues; it is important that your dog has regular checkups, and that any changes in health or behavior are discussed.
A common cause of blindness in dogs is cataracts, a condition in which a change in protein alters the lens of the dog’s eye, changing the normally clear lens white. As the lens becomes more opaque, the dog is able to see less and less. While many dogs develop cataracts in their senior years, genetics can cause it to develop in younger dogs. Dog breeds genetically inclined to developing cataracts include the Boston Terrier, Golden Retriever, Labrador Retriever, and others.
Glaucoma is another condition that can lead to blindness. Fluid accumulates within the eye and causes pressure to build inside. Sometimes, glaucoma is treated using surgical and medicinal therapies, but in the worst cases, retinal cells deteriorate and blindness results. If severe glaucoma is left untreated for a long enough time, the veterinarian may recommend removal of the eye. Glaucoma can occur in some older dogs, but can also be a result of genetics. Some dog breeds are said to be more prone to developing glaucoma than others; the Shih Tzu, Siberian Husky, and Bouvier des Flandres are a few that are genetically susceptible.
Other acquired conditions that may result in blindness include retinal dysplasia and detachment, Sudden Acquired Retinal Degeneration (SARD), and Progressive Retinal Atrophy (PRA).
Sometimes, a dog is born with visual impairments. Microophthalmia is a congenital malformation of the eye. A dog with this condition is born with small, underdeveloped eyes that either allow for very low or no vision. Dogs with anophthalmia were born with no eyes at all.
Finally, injuries to the eye can leave a dog visually impaired. If a dog experiences blunt trauma, for example, it can result in bulging eyes or detached retinas. Severe cuts, gouges, scrapes, punctures, and scratches can cause blindness as well.