Pig tail length is associated with the prevalence of tail malformations but not with inflammation of the tail.

backgroundAssuming that tail length is associated with the prevalence of tail biting, attempts are being made to shorten tails by genetic selection in order to avoid the painful procedure of docking. However, undesirable side effects such as kinky tails and inflammatory changes may occur. The aim of the present study was to clinically quantify in a population with known segregation of tail length, i) its variability, ii) possible associations with kinked tails and iii) possible associations of tail length and kinks with inflammation of the tail using 348 piglets at day 3 (undocked) and 39 (docked tails) of life.

resultsThe relative tail length (tail tip to tail base/tail tip to ear base × 100) varied between 20.3 and 31.3%. A reduced tail length was associated with kinked tails. Piglets with the shortest tails had 28% kinked tails, 5.6 times more than the piglets with the longest tails. The tails showed high prevalence of inflammation both on day 3 and on the docked tails on day 39. Overall, these were not associated with tail length or kinked tails. Only necrosis of the tail was significantly more frequent in the kinked tails than in the normal tails. Sow line, sow ID and boar ID significantly affected relative tail length, which may suggest a genetic cause.

conclusionBased on the phenotypic variation found in the present study, it seems possible to influence tail length through breeding. It remains to be seen whether the available potential is sufficient to actually reduce tail biting. At the same time, a higher incidence of kinked tails and necrosis is to be expected.