The impact of transportation on wounds up to 4 cm on umbilical outpouchings of slaughter pigs

Background: In Denmark, pigs with wounds on umbilical outpouchings (UO) are deemed unfit for transport, due to welfare concerns, particularly the risk of wound rupture when these pigs are transported. Consequently, these pigs are often killed on-farm thereby affecting sustainability of pork production and farmers’ economy. To gain more knowledge on the impact of transportation on wounds on UOs of pigs, this study examined 96 Danish slaughter pigs with wounds on the UOs and investigated how clinical signs were associated with the distance between the wound surface and the cavity of the UOs measured at necropsy. The pigs originated from three conventional herds and were clinically examined by the herd veterinarian the day before transport to the abattoir. From the abattoir, the UOs were sent for pathological examination at University of Copenhagen where the distance between the wound surface and the peritoneal lining of the cavity of the UOs was measured. Results: The results showed that the maximum measurement of either the length or width of the wound measured clinically was 2.93 cm (σ = 0.97). The mean distance between the wound surface and the cavity of the UOs of 87 slaughter pigs was 2.27 cm, and a total of 94% had a distance of at least 1 cm. For one pig there was access from the UO wound to the UO cavity. The association between size of the wound and the distance between the wound surface and the UO cavity, depended on the shape of the UO. If the UO was elongated in shape no significant association was found, however, if the UO was spherical in shape the distance became significantly shorter as the wound became larger. The study also investigated if the wounds on the UOs changed in size when measured before and after transport to the abattoir. Wound size measured clinically and at necropsy showed a correlation of 0.51, indicating a moderate correlation. When comparing the wound sizes clinically and just after individual slaughter the correlation was 0.7 indicating a moderate to strong correlation. With a ± 10% difference from the baseline, a total of 28 wounds measured larger at the abattoir compared to the clinical examination. Conclusions: This study found that 94% of the wounds on UOs of 87 slaughter pigs examined post mortem had a distance of at least 1 cm from the wound surface to the UO cavity. In one pig the wound had ruptured giving access from the UO wound to the UO cavity. While a number of other factors also need to be considered when evaluating fitness for transport, the results from this study may serve as part of a risk assessment for transporting slaughter pigs with wounds on UOs in the future.