Observations on the efficacy of mass treatment by subconjunctival penicillin injection for the control of an outbreak of infectious bovine keratoconjunctivitis

Infectious bovine keratoconjunctivitis was diagnosed on a Manawatu beef cattle farm, with inflammation of 85% of eyes in a group of 150 6-month-old-calves. Comeal inflammation was recorded in 23% of eyes. All active lesions healed over a 3-week period following whole group subconjunctival penicillin injection. Morarellu bovis was cultured from two of seven conjunctival swabs at the time oftreatment and from four of six conjunctival swabs 9 days after treatment. Concurrently, pink-eye was noted in older cattle, with inflammation in 50% of eyes. For practical handling reasons, these older cattle were not treated. Despite nontreatment, their clinical signs regressed over a 3-week period. The rationale of whole group treatment for the control of infectious bovine keratoconjunctivitis is discussed.