Sow shoulder lesions: risk factors and treatment effects on an Ontario farm

The objectives of this study were to identify risk factors for the development of shoulder lesions in lactating sows and to determine if an effective, economical, and practical treatment could be designed. The study was conducted at a 300-sow farrow-to-finish swine farm in Ontario between July and December 2004. Sow data were recorded on either the day of or 1 d after entering the farrowing crate and before farrowing had occurred. The right and left shoulders of the sows were assigned a score between 0 (normal) and 4 (lesion > 2.3 cm in diam.) on d 1 of the study and weekly thereafter throughout lactation. If a lesion developed, sows were randomly placed into 1 of 3 treatment groups. Groups consisted of a control group that received no treatment, a group that had a 0.2-cm thick, 60 x 60-cm, stainless steel plate attached to the bottom of the farrowing crate, and a group that had a 3.8-cm thick, 60 x 60-cm rubber mat attached to the bottom of the farrowing crate. Of the 310 sows involved in the study, 107 (34%) developed a lesion with a score of 3 or 4. Multivariate regression analysis identified body condition at weaning, flank-to-flank measurements at weaning, breed, parity, farrowing room section, and weaning weight of the litter as significantly associated with development of a shoulder lesion of score 3 or 4. The average number of days for the lesions to be completely resolved was 25 for sows receiving rubber mats, 32 for the controls, and 39 for the sows receiving stainless steel plates. Rubber mats attached to the bottom of the farrowing crates decreased the time required to heal the lesions when compared with controls. The low cost per mat (less than 0.90 dollars factoring in repeated use) makes it an economical and effective treatment.