Multisite randomised controlled trial to evaluate polypropylene clips applied to the breech of lambs as an alternative to mulesing. I: effects on body weight, breech bare area measurements and scores, wrinkle scores and faecal and urine staining

Aust Vet J. 2012 Nov;90(11):415-22. doi: 10.1111/j.1751-0813.2012.00961.x.


Objective: To assess the effects of application of occlusive polypropylene clips to lambs on body weight, breech bare area measurements and scores, wrinkle scores, and faecal and urine stain scores.

Procedures: A randomised controlled trial using 32,028 lambs was conducted on 208 properties across Australia. Polypropylene clips were applied at lamb marking. At each site, 160 lambs were weighed, measured for breech bare area and scored for bare area, wrinkle, dag and urine staining, and skin type and thickness. Lambs were allocated to a control (no clips) or treatment (breech and tail clips) group. Lambs were assessed on days 14 (range 10-19) and 55 (range 34-129) after clip application for body weight, breech bare area measurements and scores. On day 55 the operators also scored wrinkling and urine staining.

Results: At an average of 55 days after treatment, treated ewe and wether lambs had 16% and 21% greater horizontal bare area measurements, and 31.7% and 32.7% higher bare area scores than control lambs, respectively. The ewes and wether lambs also had lower wrinkle (6.8% and 5.8%, respectively) and dag scores (12% and 12.3%, respectively) than controls. Treated ewes had lower urine stain scores (18.8%) than controls. However, body weight was slightly lower in clip-treated lambs compared with controls by 0.320 kg (1.2%) and 0.430 kg (1.6%) for ewes and wethers, respectively.

Conclusion: Polypropylene clips applied to the breech and tail of lambs increased breech bare area and reduced dag, urine and wrinkle scores. Improvements in these measures of factors that predispose to blowfly strike suggest that the application of clips may reduce the risk of breech flystrike.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Welfare
  • Animals
  • Animals, Newborn
  • Body Weight / drug effects*
  • Diptera / drug effects*
  • Diptera / growth & development
  • Female
  • Insect Control / methods*
  • Male
  • Myiasis / prevention & control
  • Myiasis / veterinary*
  • Polypropylenes / pharmacology*
  • Sheep
  • Sheep Diseases / prevention & control*
  • Sheep Diseases / surgery
  • Tail / surgery
  • Treatment Outcome
  • Wool / standards*


  • Polypropylenes