Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

way on both tests. A dog with some sight will show more confidence when
the lights are on. Performance tests such as these give qualitative information
about eyesight, but the degree of impairment can only be determined by veterinary
examination.
A diagnosis of blindness or irreversible vision loss is not a catastrophe. The
fact is that most dogs, even those with normal eyesight, do not really see very
well. They rely to a greater extent on their keen senses of hearing and smell.
These senses take over and actually become more acute as eyesight fails. This
makes it relatively easy for visually impaired dogs to get around in areas they
know. However, a blind dog should not be turned loose in unfamiliar surroundings
or he could be injured. In the house, try to avoid moving furniture,
because your dog will have a “mental map” of where things are. When left
outdoors, confine a visually impaired dog to a fenced yard or run. Walking on
a leash is safe exercise. The dog learns to rely on his owner as a “seeing-eye
person.”
It is important to be aware of impending blindness while the dog is still
able to see. This allows time for retraining in basic commands such as “stop,”
“stay,” and “come.” When the dog actually does go blind, obedience training
can be a lifesaver.
CATARACTS
A cataract is a loss of normal transparency of the lens. Any opaque spot on
the lens, regardless of its size, is technically a cataract. A cataract that is visible
to the naked eye appears as a milky gray film behind the pupil.
The majority of cataracts in dogs are genetically determined, but the mode
of inheritance varies among breeds. Congenital cataracts (also called juvenile
cataracts) have been described in
more than 75 breeds, including
Cocker Spaniels, Bichons Frises,
Boston Terriers, Wire Fox Terriers,
West Highland White Terriers,
Miniature Schnauzers, Standard
Poodles, Siberian Huskies, Golden
Retrievers, Old English Sheepdogs,
and Labrador Retrievers. Juvenile
cataracts appear in dogs before they
are 6 years of age and usually involve
both eyes, although not necessarily
at the same time. A genetic test for
some of the affected breeds is under
development through VetGen (see
appendix D).
THE EYES • 197
This dog has a juvenile cataract in the
left eye.