Combined parenteral and oral administration of oxytetracycline for control of infectious bovine keratoconjunctivitis.

OBJECTIVE

To determine whether combined parenteral and oral administration of oxytetracycline would ameliorate a herd outbreak of infectious bovine keratoconjunctivitis (IBK) and to compare efficacy of this regimen with that of subconjunctival administration of procaine penicillin G.

DESIGN

Randomized field trial.

ANIMALS: 119 Hereford calves in a herd undergoing a naturally occurring outbreak of IBK.

PROCEDURE: Calves were randomly assigned to 1 of the following 3 groups: oxytetracycline treatment, procaine penicillin G treatment, and control. After initial treatment, calves were examined 3 times/wk for 7 weeks. The surface area of all corneal ulcers was measured during each examination. Ocular secretions were collected from all calves at least weekly and were tested for Moraxella bovis.

RESULTS

Calves treated with oxytetracycline had a lower prevalence of IBK than did calves treated with procaine penicillin G or control calves and required fewer additional treatments than did calves treated with procaine penicillin G. Mean time for healing of corneal ulcers was significantly less for calves that received oxytetracycline or procaine penicillin G than for control calves. Calves treated with oxytetracycline developed fewer corneal ulcers and fewer recurrent ulcers than did calves in the other groups. Moraxella bovis was isolated less often from ocular secretions collected from calves in the oxytetracycline group than from calves in the other groups.

CLINICAL IMPLICATIONS: Combined parenteral and oral administration of oxytetracycline appears to be an effective method of reducing severity of a herd outbreak of IBK and may be superior to treatment of affected animals with procaine penicillin G.