Septic tendosynovitis in a breeding ram and isolation of <i>Mycoplasma arginini</i>

Abstract A breeding ram was submitted to a veterinary hospital due to persistent pneumonia, emaciation and high fever. Upon submission, it also showed severe weight‐bearing lameness on all four legs with highly fluid‐filled digital flexor tendon sheaths. Additionally, a mild brisket sore was diagnosed. The postmortem examination revealed a chronically active fibrinosuppurative inflammation of the digital flexor tendon sheaths on all four legs. Additionally, a distinctive chronically active necrotising, suppurative and abscess‐forming soft tissue inflammation was identified in the sternal area. Microbiological examination of tissue samples from different locations revealed a mixed bacterial colonisation including Escherichia coli, Klebsiella oxytoca and Trueperella pyogenes . Additionally, Mycoplasma arginini was detected in samples of the lung and tendon sheaths. Genome sequencing and characterisation of M. arginini revealed the presence of a prophage associated with arthritogenesis in related Mycoplasma species. However, the contribution of M. arginini to the diagnosed tendosynovitis cannot be conclusively clarified.