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Pannus
(Chronic Superficial Keratitis)
PetPlace Veterinarians
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A
thick grey white infiltrate is covering ¾ of the left cornea of
this 3-year-old German shepherd dog. The cornea is opaque, thickened
and roughened. Photo provided courtesy of Dr. Rhea Morgan |
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Pannus,
also referred to as chronic superficial keratitis, is a chronic
inflammation of the cornea and sometimes the third eyelid of both eyes.
It arises as a gray, pink film that spreads across the eyes and
eventually decreases the dog's vision. As the lesion progresses,
superficial vessels invade the cornea and the cornea becomes opaque.
With time the cornea becomes thickened and the surface may become rough
and pitted.
The cause of
pannus is believed to be an immune-mediated inflammation of the cornea
that is made worse by external factors. Exposure to ultraviolet
radiation and environmental pollution increases the severity of the
condition. Dogs that live in areas of extensive sunlight, especially at
high elevations tend to have the worst clinical signs. Pannus is not
painful, but advanced cases may lead to blindness.
Pannus occurs
only in dogs. Most affected dogs are middle-aged, but the disease can
develop in young adult dogs.
Pannus occurs
predominantly in German shepherd dogs and German shepherd-cross dogs;
it also occurs uncommonly in the greyhound, rottweiler, Belgian
tervuren, Border collie, golden retriever, and Australian shepherd.
What
to Watch For
Pannus usually
begins as a somewhat symmetrical fleshy, pink-white film that begins at
the lower, outer edges of the cornea of both eyes.
Redness and
tearing may be noted.
With time the
corneas can pigment and turn dark brown.
White fatty
deposits in the adjacent cornea may also develop.
The entire
cornea may appear opaque.
Vision may be
decreased.
The third eyelid
may appear thickened or become pink in color.
The condition is
not usually painful unless it is complicated by ulceration of the
cornea.
Diagnosis
Diagnostic tests
are necessary to recognize pannus and to exclude other diseases, such
as the following:
Keratoconjunctivitis
sicca
Corneal
ulceration
Corneal
granulation tissue from ocular trauma
Pigmentary
keratitis
Squamous cell
carcinoma of the cornea and/or third eyelid
The diagnosis of
pannus is almost always made based upon the clinical history and the
appearance of the eye. Your veterinarian will usually perform a
complete eye exam that includes:
Schirmer tear
test to rule out tear deficiency (dry eye)
Fluorescein
staining to look for ulceration of the cornea
Thorough
examination of the eyelids and adjacent structures of the eye
Your
veterinarian may elect to refer your dog to a veterinary
ophthalmologist for a comprehensive eye examination, to confirm the
diagnosis and to obtain advice on the best therapies to institute.
Treatment
Pannus is a
disease that is controllable, but not usually cured. Treatment of
pannus relies on the use of topical corticosteroids and
immune-modulating agents such as cyclosporine. In many cases the use of
topical drugs can be decreased in frequency as the pannus comes under
control, but the drugs cannot usually be stopped entirely. Rarely does
the problem completely resolve and the vast majority of cases require
lifelong therapy.
Topical
corticosteroids are the mainstay of therapy. Medications may include
dexamethasone, prednisolone phosphate, betamethasone or prednisolone
acetate, which are instituted two to four times daily.
Steroids may be
injected under the conjunctiva in severe cases and are given in
addition to topical steroids. These injectable steroids include
methylprednisolone, triamcinolone, or betamethasone.
Topical
cyclosporine 0.2% ointment (Optimmune) is also helpful, particularly in
the control of pannus of the third eyelid. Topical cyclosporine is
usually used in conjunction with topical steroids, and often allows the
frequency of the steroids to be reduced.
For severe cases
of pannus that are refractory to the usual treatments, radiation
therapy with beta-irradiation may be considered.
Home
Care and Prevention
It is important
to follow the instructions given to you by your veterinarian. Periodic
ocular examination is recommended to evaluate the effectiveness of
treatment. Following initiation of therapy, the dog is often rechecked
within two to three weeks. Subsequent rechecks are often recommended
one month later, three months later and eventually every four months
for the rest of the dog's life.
Pannus is
typically not preventable, but controlling certain environmental
factors can help in the control of the disease. Affected dogs should
have limited exposure to bright sunlight. They must also be monitored
for seasonal or periodic exacerbations of the disease. Recurrences
often develop during warm, sunny weather or at times of significant
snow glare.
This article has been provided
courtesy of PetPlace.com
(
www.petplace.com), the
definitive online source for pet news, health,
and wellness information
The above information is simply informational. It's intent is
not to replace the advice of a veterinarian nor to assist you in making
a diagnosis of your pet. Please consult with your own veterinarian for
confirmation of any diagnosis. Your pets life may depend on it.