Guinea Pig Lymphadenitis Study Guide

Overview and Clinical Importance

Cervical lymphadenitis (also known as caseous lymphadenitis or "lumps") is one of the most common and clinically significant infectious diseases in guinea pigs. This condition is characterized by abscessation of the cervical and submandibular lymph nodes, most commonly caused by Streptococcus equi subspecies zooepidemicus, a Gram-positive, beta-hemolytic, Lancefield Group C bacterium. The disease represents a significant cause of morbidity in both pet and commercial guinea pig populations and carries important zoonotic implications.

Understanding the pathogenesis, clinical presentation, diagnosis, and treatment of lymphadenitis is essential for veterinary practitioners, as this condition frequently appears on the NAVLE. Additionally, practitioners must recognize the zoonotic potential of S. zooepidemicus and counsel clients appropriately about handling affected animals.

Etiology

Primary Causative Agent

Streptococcus equi subspecies zooepidemicus is the most common cause of cervical lymphadenitis in guinea pigs. This organism is a Gram-positive, beta-hemolytic, encapsulated coccus that forms chains on Gram staining. It is classified as Lancefield Group C streptococcus and is commonly carried asymptomatically in the nasopharynx of guinea pigs.