Docked tail length is a risk factor for bacterial arthritis in lambs

- Tail docking is used to reduce the susceptibility of sheep to breech fly strike.
- An association was found between short tail docking and bacterial arthritis in lambs.
- Regional source and breed were also risk factors for arthritis.
- Erysipelothrix rhusiopathiae was the bacterium most commonly isolated from abnormal joints.
- Streptococcus suis was identified as an emerging cause of joint infections in Australian lambs.

Arthritis is commonly observed in lambs at slaughter, resulting in losses due to carcase downgrading, trimming or condemnation. The condition arises on-farm and is thought to be influenced by a number of predisposing factors, which vary in their ability to be addressed by sheep producers. The aim of this study was to investigate whether there is a link between tail length and arthritis in lambs. If there is, leaving a longer tail stump when docking may be a cost-effective way of reducing the prevalence of joint infections in lambs. The study was conducted at an abattoir in South Australia and included 63,287 carcases. This study found a correlation between short-docked tails (fewer than three coccygeal vertebrae remaining) and bacterial arthritis in lambs. Other risk factors for arthritis included breed and the regional source of the lambs, but not age. The constraints of data collection within the abattoir did not allow the effects of tail docking method, sex or whether male lambs had been castrated on the prevalence of bacterial arthritis to be determined. The bacterium most commonly isolated from abnormal joints was Erysipelothrix rhusiopathiae, followed by Streptococcus spp., including Streptococcus suis.