Inflammation of the cornea. Keratitis may be deep, when the infection causing it is carried in the blood or spreads to the cornea from other parts of the eye, or superficial, caused by bacterial or viral infection, trauma, or by allergic reaction. The clinical signs include pain, blepharospasm, ocular discharge, and when chronic, pigmentation.
- chronic superficial k. — a progressive cellular infiltration with vascularization and eventually pigmentation of the cornea that usually commences at the temporal (lateral) quadrant and advances towards the center. The whole cornea may become involved. It occurs in dogs, particularly German shepherd dogs. The cause is unknown, but exposure to ultraviolet light may be a factor. Cellular infiltrates suggest immune mechanisms are involved in the pathogenesis. Called also CSK, degenerative pannus, Uberreiter's syndrome.
- eosinophilic k. — a superficial neovascularization and cellular infiltration of the cornea, beginning at the temporal limbus, in adult cats. Eosinophils and plasma cells are found in conjunctival or corneal scrapings and biopsies, and a peripheral eosinophilia is sometimes present. The cause is unknown, but it may be immune-mediated.
- exposure k. — keratitis resulting from ineffective or incomplete closure of the eyelids with drying of the corneal tear film. Occurs in paralysis of the eyelids, brachycephalic dogs with prominent globes, and cats during ketamine anesthesia. See also lagophthalmos.
- herpetic k. — herpesvirus infections of the cornea occur in feline and bovine rhinotracheitis infections, and are suspected in dogs. In cats there may be ulcerative keratitis with dendritic ulcers; in cattle conjunctivitis is more common than keratitis.
- infectious k. — see thelazia, onchocerca, moraxella bovis.
- interstitial k. — inflammation of the substantia propria, causing dense corneal clouding.
- mycotic k. — see keratomycosis.
- neurotrophic k., neuroparalytic k. — a chronic keratopathy resulting from impairment of the sensory (trigeminal) innervation of the cornea.
- k. nigrum — see corneal sequestrum.
- k. sicca — see keratoconjunctivitis sicca.
- superficial diffuse k. — see chronic superficial keratitis (above).
- superficial pigmentary k. — a pigmentation of epithelium and superficial stroma of the cornea, resulting from chronic keratitis from a variety of causes. Seen most commonly in brachycephalic dogs in which the contributing factors are exposure keratitis, distichiasis, irritation from the nasal folds and sometimes keratoconjunctivitis sicca.
- superficial punctate k. — a keratopathy with discrete opacities of the cornea, without ulceration. Can be caused by irritation.
- ulcerative k. — see corneal ulcer.
