A closed breeding colony comprising genetically engineered, wild-type, and stock mice presented with varying degrees of bilateral mucopurulent conjunctivitis and panophthalmitis. The one mouse with unilateral corneal ulceration, a knockout animal, was submitted for necropsy, and bacterial culture samples were obtained from the affected eye and uterus. In addition, ocular swabs from another 12 clinically affected animals, consisting of knockout, transgenic, wild-type, and stock mice, were submitted for bacterial culture analysis. All samples revealed pure cultures of Pasteurella pneumotropica. At the time of the outbreak, there were approximately 600 mice in the affected colony, with the majority of clinical cases (58 of 79) involving knockout mice and the remainder (21 of 79) in the other strains. Treatment consisted of enrofloxacin in the drinking water at 85 mg/kg daily for 14 days. Within 7 days of initiation of treatment, all existing clinical cases had resolved and no new clinical cases developed. Four weeks after completion of treatment, two groups of mice were submitted for multiple organ bacteriological analyses. One group of mice represented those animals which had complete resolution of clinical signs, and the second group of mice represented those individuals which had remained asymptomatic throughout the outbreak. All post treatment bacterial culture samples were negative for Pasteurella pneumotropica. By using the oral enrofloxacin suspension in the drinking water rather than the parenteral counterpart, concerns regarding the pharmacokinetics, specifically drug bioavailability via the oral route, problems with aqueous immiscibility and drug degradation within an aqueous medium were not potentially confounding variables. The clinical management, ease of administration, and efficacy of using an oral antibiotic formulation for the treatment and eradication of Pasteurella pneumotropica from a large mouse colony are presented in this paper.