Animal Industry Report

Extension Number

ASL R2626



Summary and Implications

There are no approved drug treatments for analgesia use in lame swine, and the identification and validation of robust, repeatable pain measurements is fundamental for the development of effective analgesic drug regimens and management strategies for use in lame pigs. Induction of lameness allows for controlled evaluation of lameness pain in animals because pre- and post lameness measurements can be taken from the same animal, thereby reducing the confounding effects of individual differences. The objective of this study was to determine if a transient clinical lameness could be produced in sows using a distal interphalangeal joint space injection of Amphotericin B. Six clinically normal crossbred sows weighing approximately 171 kg were purchased from a commercial producer in Iowa and housed in individual pens at Iowa State University.

Sows were randomly allotted to one of three treatments, two sows received 1 ml sterile saline control (CO), two sows received 10 mg amphotericin B in a 1 ml volume (LO) and two sows received 15 mg amphotericin B in a 1ml volume (HI). Sows were assessed for lameness while walking and standing based on a five point and data was collected using a GAITFour® gait analysis walkway system. Data will be presented descriptively. All sows were scored as 0 at the onset of the trial for lameness. At 24 h post injection, the average lameness scores were 2.75, 2.00, and 0.50 for the HI, LO and CO sows respectively. The CO sows’ average returned to 0 at 72 h post injection, HI sows’ average returned to 0 at 144 h, and LO sows’ average score returned to 0 at 192 h post injection.

On the GAITFour system, the total number of sensors activated (SEN) decreased for the amphotericin treated feet suggesting a smaller footprint and pressure was shifted to the non-treated foot at 48 h post injection. These changes resolved by 144 h post injection. It was demonstrated using this “proof of concept” pilot study that injection of 10 or 15 mg of amphotericin B in the distal interphalangeal joint of the medial claw of the rear foot causes clinical lameness in sows that is distinguishable from their pre-treatment gait by observational lameness score, and objective GAITFour measurement. Additionally, this lameness spontaneously resolved in this study by 192 h post injection.

Copyright Holder

Iowa State University