Abstract: Through epidemiological investigation，clinical symptom observation，necropsy analysis，bacterial isolation and identification，and viral detection，this study examined multi⁃pathogen infections and drug susceptibility in reserve breeding pigeons from a large⁃scale pigeon farm in Guangdong under high⁃temperature and high⁃humidity conditions. The results revealed that the diseased pigeon flock was primarily infected with Newcastle disease virus （NDV），H9N2 subtype avian influenza virus，and pigeon circovirus（PiCV），accompanied by co⁃infections with Escherichia coli and Salmonella. Drug susceptibility testing showed that the pathogens were highly sensitive to gentamicin.The findings suggest that PiCV infection may enhance the susceptibility of pigeons to H9N2 avian influenza and play a critical role in mixed infections. This study provides clinical evidence for understanding the mechanisms of mixed infections in pigeons under immunosuppressive conditions and offers valuable insights for the comprehensive prevention and control of pigeon diseases.

Key words: Reserve breeding pigeon, NDV, H9N2, PiCV

摘要： 该文通过流行病学调查、临床症状观察、剖检分析、细菌分离鉴定及病毒检测，对广 东地区某规模化鸽场后备种鸽在高温高湿环境下的多病原体感染及药物敏感性进行了研究。 结果显示，患病鸽群主要感染新城疫病毒（NDV）、H9N2 亚型禽流感病毒和鸽圆环病毒 （PiCV），并伴随大肠杆菌和沙门氏菌感染。药敏试验表明，病原菌对庆大霉素高度敏感。研 究发现，PiCV感染可能增强了鸽群对H9N2亚型禽流感的易感性，并在混合感染中起关键作 用。该研究为揭示免疫力低下条件下鸽群混合感染机制提供了临床依据，并对鸽病综合防治 具有重要参考价值。

关键词: 后备种鸽, NDV, H9N2, PiCV