Blindness is the loss of vision in both eyes. Vision loss may arise from disorders of the structures that receive and process the image within the eye or from disorders of the visual pathways that transmit and further process the image within the brain.

Acute (sudden) blindness occurs when vision is lost in both eyes simultaneously. The actual onset of blindness may be difficult to pinpoint because dogs' senses of hearing and smell can often compensate for a decrease in vision. When one eye is blind, most dogs act and behave normally. The owner may not realize vision has been lost in one eye, until such time as it is decreased in the other eye. If an acute loss of sight occurs in the other eye from a disease or injury, then the dog may seem to go acutely blind.

At times the realization that the pet is blind only occurs when a change in the environment confuses the pet. Animals that slowly lose their vision memorize their surroundings, and if those surroundings are altered, then the behavioral changes they exhibit may make the owner conclude that the animal has gone blind suddenly. In actuality, the blind dog starts bumping into things only because the environment has changed.

Blindness in some pets may not be observed until vision is lost in eyes that had minimal function previously. Causes of blindness include severe corneal disease, anterior and/or posterior uveitis, cataracts (white opacity of the lens), retinal inflammation and infection, retinal detachment, glaucoma (sustained elevated pressure within the eye), disease of the optic nerve (nerve that connects the eye to the brain) and visual pathways, and diseases of the occipital cortex (visual center of the brain).

What to Watch For

Occasional clumsiness

Bumping into objects

Inability to find food and water dishes

Inattentive behavior, excessive sleeping

Easily startled, fearful behavior

Loss of normal play or interactive behaviors

Becoming lost in the yard or certain areas of the house