Sow lameness is a production disease affecting not only animal welfare but also swine profitability. Second to reproductive problems, lameness is a major cause for premature sow culling in the swine industry (Anil et al., 2005). It has been estimated that 32% of sows culled for lameness have only produced one litter (Boyle et al., 1998). Lameness has been estimated to cost the United States swine industry approximately $23 million/year (Butters-Johnson et al, 2011).

The overall goal of this thesis was to validate diagnostic tools using a naturally occurring sow lameness model. This work was completed through four objectives: 1) to determine if behavior assessments, mechanical nociceptive threshold testing and walking and standing lameness scoring could identify a lame sow, 2) to determine if behavior assessments, mechanical nociceptive threshold testing and walking and standing lameness scoring were affected by the body system suspected to be contributing to the lameness identified using the Swine Lameness Diagnostic Manual, 3) to determine lameness etiology within the suspected body system as guided by the Lameness Diagnostic Manual, 4) to evaluate the accuracy of the suspected lameness etiology using the results of the Swine Lameness Diagnostic Manual, standing lameness scoring, locomotion lameness scoring and swine veterinarian expertise.

The results of this thesis identified that the walking and standing lameness scoring systems and behavior are promising tools for a producer to use on farm for lame sow identification. However, behavior assessments, mechanical nociceptive threshold testing and walking and standing lameness scoring were less correlative when evaluating the body system suspected to influence lameness. The Swine Lameness Diagnostic Manual was able to identify a presumptive lameness etiology for each case. However, a panel of practicing swine veterinarians unanimously agreed that the manual identified the correct and complete lameness etiology on only 4.3% of the cases after reviewing all data and diagnostic testing for each case.