Original articleDetection of Chlamydia pecorum in joints trimmed from ovine carcases with arthritis at an abattoir in southern Australia

- The prevalence of C. pecorum in trimmed abnormal joints was determined by qPCR.
- Nine of 148 synovial samples tested positive for C. pecorum (prevalence 6.1%).
- None of the positive carcases were condemned for systemic involvement.
- The arthritis trim weight of positive and negative carcases did not differ.

Chlamydiae are obligate intracellular bacteria that infect a broad range of host species, including sheep. Two species of Chlamydia infect sheep, C. abortus, which is a major cause of abortion in both sheep and goats, and C. pecorum, which causes pneumonia, arthritis/polyarthritis, encephalomyelitis, conjunctivitis, enteritis, abortion and metritis and infertility in domestic ruminants and pigs. The prevalence of faecal shedding of C. pecorum is relatively common amongst lambs in Australia. The aim of the work presented here was to use qPCR to determine the prevalence of C. pecorum in synovial samples obtained from abnormal joints trimmed from lamb carcases at one abattoir in southern Australia. The study included 53,131 carcases screened for arthritis, of which 369 had at least one abnormal joint trimmed. One hundred and forty eight trimmed joints were undamaged and suitable for PCR testing. The prevalence of C. pecorum in synovial tissue collected from the abnormal joints was 6.1% and the bacterial concentration ranged from 6 × 103 to 7.6 × 105/g of synovial tissue. Five of the positive joint samples were from carcases that had one joint trimmed for arthritis and four were from carcases from which two joints had been trimmed. None of the carcases from which the positive joint samples originated were condemned. The average arthritis trim weight of the carcases from which synovial tissue tested positive for C. pecorum was 1.112 kg (95% confidence interval 0.637-1.586 kg) and this did not differ from the carcases from which synovial tissue was not positive for C. pecorum. (mean 0.997 kg, 95% confidence interval 0.840-1.154 kg). Further research is required to determine the on-farm production losses associated with C. pecorum infection in Australian lambs.