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

194 •DOG OWNER’S HOME VETERINARY HANDBOOK
eye pain, infectious keratitis is characterized by a purulent discharge from the
eye. The eyelids are swollen and matted. This might, at first, suggest conjunctivitis
(which could seriously delay diagnosis and treatment), but recall that
conjunctivitis is not usually accompanied by signs of a painful eye.
Treatment is similar to that described for Corneal Ulcer (page 192). It is important
to use topical antibiotics selected following culture and sensitivity tests.
Fungal keratitis is uncommon in dogs, but may occur with the prolonged
use of topical antibiotics. The diagnosis is made by fungal culture. It is treated
with antifungal drugs.
Interstitial keratitis (blue eye) is a corneal inflammation in which a
bluish-white film appears over the clear window of the eye. It is caused by the
same virus that causes infectious hepatitis, and at one time it occurred after
vaccination with CAV-1 (vaccines with this version of the hepatitis virus are
no longer used). Signs appear 10 days after exposure. The eyes begin to water
and the dog squints and avoids light. Most dogs recover completely within a
few weeks. In some cases the eye remains permanently clouded.
Vascular keratitis is caused by neovascularization—the process by which
the transparency of the cornea is lost due to an ingrowth of blood vessels and
connective tissue. You can see blood vessels growing onto the cornea with
your naked eye.
Pigmentary keratitis results when melanin pigment is deposited in the
cornea. This is a separate process, but is often associated with vascular keratitis.
Both conditions interfere with vision and may progress to blindness.
Vascular and pigmentary keratitis may, in some cases, be the result of a
chronic corneal irritation such as that caused by entropion or lagophthalmos
(inability to completely close the eyes). Removing the initiating process may
reverse the keratitis.
Blood vessels are growing
on the surface of this
dog’s eye (pigmentary
keratitis), in this case
caused by lack of tears
(keratoconjunctivitis
sicca).