The objective of this study was to quantify pain sensitivity differences using mechanical nociception threshold (MNT) and thermal nociception threshold (TNT) tests when sows were in painful and nonpainful transient lameness phases. A total of 24 mixed parity crossbred sows (220.15 ± 21.23 kg) were utilized for the MNT test, and a total of 12 sows (211.41 ± 20.21 kg) were utilized for the TNT test. On induction day (D0), all sows were anesthetized and injected with Amphotericin B (10mg/mL) in the distal interphalangeal joint space in both claws of one randomly selected hind limb to induce transient lameness. Three days were compared: (1) D-1 (sound phase, defined as 1 d before induction), (2) D+1 (most lame phase, defined as 1 d after induction), and (3) D+6 (resolution phase, defined as 6 d after induction). After completion of the first round, sows were given a 7-d rest period and then the procedures were repeated with lameness induced in the contralateral hind limb. During the MNT test, pressure was applied perpendicularly to 3 landmarks in a randomized sequence for each sow: 1) middle of cannon on the hind limb (cannon), 2) 1 cm above the coronary band on the medial hind claw (medial claw), and 3) 1 cm above the coronary band on the lateral hind claw (lateral claw). During the TNT test, a radiant heat stimulus was directed 1 cm above the coronary band. The data were analyzed using the MIXED procedure in SAS with sow as the experimental unit. Differences were analyzed between sound and lame limbs on each day. For the MNT test, pressure tolerated by the lame limb decreased for every landmark (P < 0.05) when comparing D-1 and D+1. The sound limb tolerated more pressure on D+1 and D+6 than on baseline D-1 (P < 0.05). Thermal stimulation tolerated by the sound limb did not change over the 3 d (P > 0.05). However, the sows tolerated less heat stimulation on their lame limb on D+1 compared to D-1 levels (P < 0.05). Both MNT and TNT tests indicated greater pain sensitivity thresholds when sows were acutely lame. ABSTRACTThe objective of this study was to quantify pain sensitivity differences using mechanical nociception threshold (MNT) and thermal (TNT) tests when sows were in painful and nonpainful transient lameness phases. A total of 24 mixed parity crossbred sows (220.15 ± 21.23 kg)were utilized for the mechanical nociception threshold test and a total of 12 sows (211.41 ± 20.21 kg) were utilized for the thermal nociception threshold test. On induction day (D0), all sows were anesthetized and injected with Amphotericin B (10mg/mL) in the distal interphalangeal joint space in both claws of one randomly selected hind limb to induce transient lameness. Three days were compared (1) D-1 (Sound phase, defined as 1 d before induction), (2) D+1 (Most lame phase, defined as 1 d after induction) and (3) D+6 (Resolution phase, defined as 6 d after induction). After completion of the first round, sows were given a 7-d rest period and then the procedures were repeated with lameness induced in the contralateral hind l...

Lameness has been ranked as the third most common reason for culling sows, comprising 15% of the culls marketed in the U.S. Producers assess sow lameness using subjective evaluation, which have been shown to be variable in their application. Objective empirical tools to measure sow lameness on farm are required. Therefore, the purpose of this study were to evaluate the embedded force plate and the GAITFour gait analysis walkway system as objective assessment tools to discriminate between sound and lame phases in multiparous sows. Twenty-four mixed parity crossbred sows were anesthetized and injected with Amphotericin B in the distal interphalangeal joint of both claws of one hind hoof to induce transient lameness. Kinematic data was collected on D−1, D+1 and D+6 relative to induction (D0). For the embedded force plate, weight distributions on each hoof were collected. Gait analysis measures collected were stride time (defined as the time (s) between 2 successive footfalls by the same hoof), stride length (defined as the distance (cm) between 2 sequential footfalls from the same hoof),maximum pressure (defined as the greatest amount of weight (kg/cm 2 ) placed on a single hoof) and stance time (defined as the duration of time (s) the sensors were activated by a hoof in a single stride). For the embedded microcomputer-based force plate system weight placed on the induced hoof decreased on D+1 when compared to D−1 (P® pressure mat gait analysis walkway system, stride time increased on D+1 for all hooves, stride length decreased on D+1 compared to D−1 and maximum pressure placed on the induced hoof decreased on D+1 compared to baseline levels (PStance time increased for all sound hooves on D+1 compared to D−1 (P Keywords force plate, gait analysis, lameness, pain, sow Disciplines Agriculture | Animal Sciences | Large or Food Animal and Equine MedicineComments NOTICE: this is the author's version of a work that was accepted for publication in Livestock Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Livestock Science, 165 (2014) time (defined as the duration of time (sec) the sensors were activated by a hoof in a single stride). 33For the embedded microcomputer-based force plate system weight placed on the induced hoof 34 decreased on D+1 when compared to D-1 (P < 0.0001). For the GAITFour ® pressure mat gait 35 analysis walkway system, stride time increased on D+1 for all hooves, stride length decreased on 36 D+1 compared to D-1 and maximum pressure placed on the induced hoof decreased on D+1 37 compared to baseline levels (P < 0.05). Stance time increased for all sound hooves on D+1 38 compared to D-1 (P < 0.05). In conclusion, the embedded force plate and GAITFour walkway 39 system all demonstrated differences for mature sows duri...

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The objective of this study was to quantify differences in thermal and mechanical nociception thresholds when sows are in painful and non-painful lameness states. Twelve, clinically healthy, mixed-parity, crossbred sows were used for each of the nociceptive threshold tests. The sow was the experimental unit and a cross-over design with a 2 (left and right hind limb) x 3 (days: D-1, D+1 and D+6) factorial arrangement of treatments were compared. On induction day (D0), 10 mg of amphotericin B were injected in the distal interphalangeal joint space in both claws of one hind limb. All sows served as their own control and treatment. After completion of the first round, sows were given a 7-d rest period and then the round was repeated with the opposite hind limb induced. All data were statistically analyzed using the PROC MIXED procedure in SAS. A P value of ≤ 0.05 was considered to be significant. No differences were observed for sows that had lameness induced in the left-vs. right hind limb for either the thermal (P = 0.68) or mechanical (P = 0.97) threshold tests. There were also no differences between first and second rounds of induction for the thermal (P = 0.18) or mechanical (P= 0.28) threshold tests. For the thermal nociceptive tests, there was a significant difference for the induced limb when comparing D-1 and D+1 (P < .0001), indicating the lame hind limb tolerated less thermal nociception when in a most lame phase. Similarly, mechanical pressure tolerated by the lame hind limb decreased for every landmark (P < 0.05) when comparing D-1 and D+1. Both tools showed a decreased tolerance of mechanical and thermal stimulation when in a most lame phase, indicating potential for limb lameness detection in sows.

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