Infectious Coryza is a tenacious respiratory disease which tends to become chronic in laying hens that were infected during rearing. Antimicrobial therapy of layer replacement flocks affected by the disease, e.g., before protection by immunisation can be established, is appropriate in order to safeguard future respiratory health.

In a clinical study (Will B., 1986), drinking water medication with Baytril® 10% oral solution was shown to be very efficacious against Infectious Coryza with rapid reduction of morbidity and full microbiological clearance from the infectious agent, Haemophilus paragallinarum, at the end of medication.