Resumen del póster presentado al Joint Meeting of 30th Meeting of the European Society of Veterinary Pathology-Annual Meeting of the European College of Veterinary Pathology and 24th Annual Meeting of the Spanish Society of Veterinary Pathology, celebrado en León (España) del 5 al 8 de septiembre de 2012. ; [Introduction]: Recent flavivirus outbreaks in avian species have shown the potential need of vaccination of birds with economic and/or ecologic value. During the study of the immunogenicity induced by two different vaccines against West Nile virus (WNV) that were being experimentally tested in red-legged partridges (Alectoris rufa), we analyzed the macroscopic and microscopic changes produced after intramuscular injection in the pectoral muscle. [Material and methods]: A commercial inactivated vaccine (Duvaxyn®, Pfizer, Spain) and an E protein based recombinant vaccine candidate with different commercial adjuvants (Stimune® and MetaStim®) were tested. They were applied intramuscularly in the pectoral muscle in two experiments. While local injection volume increased, injection frequency decreased between experiments. During necropsies, pectoral muscle samples were collected for microscopic examination. [Results]: No mortality or clinical signs were observed related to vaccinations. At necropsy, white or yellowish nodules were seen in the pectoral muscle. Microscopic changes included myofibril degeneration, inflammation and oil cysts (the latter only with the recombinant vaccine). Severity of lesions increased with injection volume and decreased as number of injection sites increased. [Discussion]: Local reactions with no apparent clinical effect are observed with both vaccines and are modified by vaccine application schemes. The implication of the adjuvants and/or other vaccine components should be studied further. ; Peer Reviewed