Just as some pets have white fur, long lashes, or a short chin, others have distinctly bulging eyes. In fact, Persian cats, Pekingese dogs, and other short-faced types of cats and dogs are bred specifically to have this appearance.

"While bulgy eyes are normal for these breeds, owners have to keep in mind that they really are a slight abnormality that can predispose the pet to eye problems, such as dry eyes," adds Terri McGinnis, D.V.M., a veterinarian in private practice in the San Francisco area and author of The Well Cat Book and The Well Dog Book.

For dogs and cats with "normal" eyes, there are several conditions that can cause the eyes to bulge. When pets get into scuffles or play too vigorously, for instance, pressure behind the eye can rise, forcing the eye partially out of the socket. Also known as a prolapsed eyeball, this condition is most likely to occur following a whack on the head or a hard bite on the neck. "Once the eyeball pops out, the eyelid clamps down behind it, trapping the protruding eyeball," explains Christopher J. Murphy, D.V.M., associate professor of ophthalmology at the University of Wisconsin School of Veterinary Medicine in Madison.

Anything that exerts pressure behind the eyes can cause them to bulge outward. Tumors or infections, for example, will sometimes cause bulgy eyes. So can an inflammation of the chewing muscle, which runs next to and under the eye, says Dr. Murphy.

A potentially serious condition called glaucoma, in which pressure builds up in the eyes, is a common cause of bulging eyes. Glaucoma sometimes comes on very quickly. If your pet's eyes are normal one day and bulging the next, glaucoma is a likely suspect. (Cocker spaniels, basset hounds, and older pets are especially prone to "fast" glaucoma.) Other signs of glaucoma include tearing, a dilated pupil, or redness in the eyes, says Dr. Murphy.

See Your Vet If...

• You have a Persian cat, Pekingese dog, or another short-faced breed
  
• Her eye is red, dilated, or teary
  
• Your pet has been fighting or roughhousing
  
• Your pet won't quit scratching or pawing his eyes
  
• His eyes have turned blue, gray, or cloudy, or he is having trouble getting around
  
• His eyes are frequently bloodshot or dry
  
• There has been a watery or discolored discharge from the eyes for 48 hours or more
  
• Your pet's eyes are bulging
  
• The eyelids are swollen or unable to close
  
• There is a growth on the eye or eyelid
  
• One or both pupils are dilated, or they don't respond to light
  
• Your pet seems very sensitive to light
  
• The eyes are droopy or sunken
  
• The third eyelids are covering the lower parts of the eyes
  
• His eyes are continually moving back and forth
  
• Blood or tiny blood vessels are visible in the center (not the whites) of his eyes
  
• His eyelid appears to be turned inward or outward
  

Next Steps:

• What you can do for your pet
  
• What your vet can do
  
• Find out other causes of bulging eyes

Copyright 1999 Rodale Press, Inc. All rights reserved.