Effect of enrofloxacin on clinical parameters and mucociliary system of broilers challenged with H9N2 avian influenza/infectious bronchitis viruses

• Published in: Veterinary medicine and science 2024-03, Vol.10 (2), p.e1390-n/a
• Main Authors: Abbasnia, Mohammad, Mosleh, Najmeh, Dadras, Habibollah, Shomali, Tahoora
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - therapeutic use; antibacterial; Avian flu; avian influenza; Bacterial infections; Birds; Body weight; broiler; Bronchitis; Chickens; Enrofloxacin; Goblet cells; infectious bronchitis; Infectious bronchitis virus; Influenza A Virus, H9N2 Subtype; Influenza in Birds - drug therapy; Mortality; mucociliary system; Necropsy; Original; Pleuropneumonia; POULTRY; Poultry Diseases; Viral diseases; Viruses
• ISSN: 2053-1095; 2053-1095
• DOI: 10.1002/vms3.1390

Background Effect of antibacterials on mucociliary system and clinical outcome of chickens with mixed viral respiratory conditions is not properly addressed. Objective We evaluated enrofloxacin effects on clinical parameters and mucociliary system of broilers challenged with H9N2/IB viruses. Methods Broilers (105), at the age of 25 days, were randomly allocated into three groups: Group 1 (negative control), no treatment; Group 2 (positive control [PC]) challenged by intranasal and intraocular route. Group 3 (antibiotic [AB]‐treated) challenged and also received enrofloxacin started after manifestation of clinical signs (day 2 post‐challenge [pc]) and continued for 5 days. Results Administration of AB was not associated with appreciable changes in body weight, feed conversion ratio (FCR) or the severity of clinical signs although it slightly reduced mortality rate as compared to PC group (p > 0.05). Virus shedding period and number of virus positive tracheal and caecal tonsil samples were also statistically similar between PC and AB groups. In necropsy, the most profound effect of AB was decreased pleuropneumonia severity score on day 12 pc. Histopathological lesion scores were statistically the same between PC and AB groups. However, the administration of AB increased the number of tracheal goblet cells, with no effect on ciliostasis. Conclusions We found a weak positive effect of enrofloxacin administration in H9N2/IB‐infected chickens. Considering the risks of AB treatment in broiler chickens, the results of this small‐scale study do not encourage the benefit of enrofloxacin use in these viral diseases. We found a weak positive effect of enrofloxacin administration in H9N2/IB‐infected chickens. Considering the risks of antibiotic treatment in broiler chickens, the results of this small‐scale study do not encourage the benefit of enrofloxacin use in these viral diseases, although performing future risk–benefit balance studies on a large number of birds and for longer periods following infection is suggested.