Ocular manifestations of low level phenothiazine administration to cattle

Feeding white face Hereford cattle a high protein dietary supplement containing 1.25% phenothiazine resulted in severe corneal edema when the cattle were exposed to sunlight. The corneal edema was located in the inferior two-thirds of the cornea. In one animal a severe secondary ulcerative keratitis developed. The corneal edema resolved in about 60-90 days after the phenothiazine containing concentrate was removed and the cattle not exposed to bright sunlight.