Page 1270 - Problem-Based Feline Medicine

1262 PART 15 CAT WITH EYE PROBLEMS

Small conjunctival biopsies can be submitted in forma- Clinical signs
lin for histopatholgy. The presence of eosinophils is
There may be evidence of the underlying cause. Most
diagnostic.
ulcers that are not associated with a specific corneal
Hematology may reveal a peripheral eosinophilia. disease are caused by corneal trauma. Foreign bodies
such as grass seeds and thorns, or blunt trauma from
Treatment motor vehicle accidents are the most common causes
of corneal trauma. Trauma may cause a superficial
The condition will rapidly respond to systemic corti- ulcer, a deep ulcer or penetrating wound.
costeroids dosed at 1 mg/kg daily.
Eyes with ulceration are invariably very painful. Cats
If the tips of the ears show alopecia, pruritis and crust- show serous ocular discharge, blepharospasm, pho-
ing, the condition may be caused by biting insects. tophobia and ocular guarding in severe injuries.
Such cases have been documented in Queensland,
Ulcers stain positive with fluorescein dye. A very
Australia. In such cases the cats must be housed in con-
deep ulcer that has formed a Descemetocele may not
ditions that are insect free.
show any staining because Descemet’s membrane will
Allergic states caused by diet have been implicated. not stain with fluorescein.
Dietary elimination tests may be useful to exclude this
Examination of the cornea with magnification will
as a cause (see The Cat With Signs of Large Bowel
show a deficit in the corneal surface because of loss of
Disease (page 766), The Cat With Abnormalities
epithelium and stroma.
Confined to the Cornea (page 1246), The Cat With
Miliary Dermatitis (page 1030), The Pruritic Cat Corneal edema will be present in cases that have loss
Without Miliary Dermatitis (page 1046). of epithelium, because fluid will be absorbed by the
stromal matrix. This will show as a cloudy cornea.
Try to minimize known causes of allergy such as insect
Edema may be focal around the ulcer, or diffuse when
bites by fleas and mosquitoes. Where there is a dietary
large ulcers are present.
component involved maintain cat on a low-antigen diet.
Penetrating injuries are common after cat fights. They
ULCERATIVE KERATITIS* present with a perforation of the cornea surrounded by
a dense area of edema and swelling. A fibrin plug may
be present in the corneal wound. If the iris has prolapsed
Classical signs
into the wound, the center of the perforation will be dark
● Severe pain with serous discharge, brown or black in color. The anterior chamber may be
blepharospasm and photobia. collapsed and contain blood (hyphema) and fibrin.
● Variable severity from a superficial
Perforating injuries that are not sealed by fibrin and/or
epithelial erosion to a deep stromal ulcer
iris, will leak aqueous so the cat will have a very wet
followed by a Descemetocele.
eye and face.
● Positive staining of the stroma with
fluorescein dye, except where a
Descemetocele is present. Diagnosis
● Varying degrees of corneal edema seen as
There may be a history of trauma or a cat fight. The
a cloudy cornea. Corneal perforation is
diagnosis of ulcerative keratitis is based on clinical
surrounded by a dense area of edema with
signs of a painful eye showing a stromal deficit.
a dark brown or black center if the iris has
prolapsed into the corneal wound. A layer The ulcer will stain with fluorescein except in the case
of fibrin may cover the injured cornea. of a Descemetocele. If the center of the ulcer is dark,
and the area bulges, there may be a Descemetocele.
See the main reference on page 1242 (The Cat With Descemet’s membrane is very elastic in cats and can
Abnormalities Confined to the Cornea). bulge forward quite noticeably.