Dysbiosis of the cervical lymph node microbiome associated with lymphadenitis in guinea pigs (Cavia porcellus)

The guinea pig (Cavia porcellus) is a native Andean rodent widely raised in Peru and other South American countries due to its adaptability, nutritional value, and low production costs, making it an important resource for food security in rural communities. In Peru, production is mainly family-based, where animal health is essential for productive efficiency. However, intensification of production systems, environmental stressors, poor sanitary conditions, and dietary changes increase susceptibility to infectious diseases.Among the most important diseases affecting guinea pigs are salmonellosis, pneumonia, and cervical lymphadenitis. Cervical lymphadenitis is characterized by chronic abscess formation, primarily in cervical lymph nodes, and is considered a highly contagious disease with significant mortality. Streptococcus equi subsp. zooepidemicus has been identified as the main etiological agent, although other bacteria such as Staphylococcus, Corynebacterium, Klebsiella, and Salmonella have also been reported in studies conducted in Peru.Conventional microbiological methods have been widely used to identify the causative agents of cervical lymphadenitis; however, these techniques may have limitations in sensitivity and specificity. Molecular diagnostic approaches, particularly PCR and 16S rRNA gene sequencing, have improved pathogen detection and taxonomic confirmation. These methods are especially valuable for identifying fastidious or emerging microorganisms, such as Caviibacter abscessus, recently associated with cervical lymphadenitis in guinea pigs. The application of molecular tools contributes to a better understanding of the etiology and epidemiology of this disease and supports more accurate diagnosis and control strategies.