Anna K. Johnson

Validation of a lameness model in sows using physiological and mechanical measurements

The objective of this study was to develop a validated, transient, chemically induced lameness model in sows using subjective and objective lameness detection tools. Experiment 1 determined an effective joint injection technique based on volume and placement of dye using feet collected from 9 finisher pigs and 10 multiparity cull sow carcasses. Experiment 2 confirmed the injection technique in live animals and produced a transient clinical lameness in 4 anesthetized sows injected with amphotericin B (15 mg/mL) in the distal interphalangeal joints of the claw. Clinical lameness was assessed by a categorical lameness scoring system, and a postmortem visual confirmation of joint injection technique was obtained. In Exp. 3, 6 sows were injected with 0, 10, or 15 mg/mL amphotericin B in either the left or right hind foot and were monitored until clinical resolution. Treated sows demonstrated elevated clinical lameness scores. These changes resolved by 7 d after lameness induction. Control sows injected with sterile saline developed a clinical lameness score of 0.5, which resolved 72 h post injection. In Exp. 4, 36 sows were injected with 10 mg/mL amphotericin B in 1 of 4 injection sites (left front claws, right front claws, left rear claws, and right rear claws). All injected sows exhibited a decrease in maximum pressure, stance time, and number of sensors activated on the GaitFour (P < 0.05) sensor system. A static force plate also demonstrated a decrease in weight (kg) being placed on the injected foot when all feet were injected (P ≤ 0.05). Injection of amphotericin B induced a predictable acute lameness that resolved spontaneously and is an effective method to model lameness in sows.

Behavioural evaluation of analgesic efficacy for pain mitigation in lame sows

Lameness in breeding swine has a large negative economic impact and is a welfare concern. Pain-related behaviour, such as postural changes, may be used to evaluate the presence and severity of pain in animals. The objective of this work was to determine the effects of flunixin meglumine (FM) and meloxicam (M) on postural changes in lame sows. Lameness was induced in 24 mature sows (Sus scrofa) using a chemical synovitis model. Three treatments were compared: FM (2.2 mg kg; n = 24, intramuscular [IM]), M (1.0 mg kg; n = 24, by mouth [PO]) and sterile saline (equivalent volume to FM; n = 24 [IM]), administered approximately 28 and 52 h after lameness induction. Behavioural data were collected in the home pen during 12-h periods and quantified using 15-min scan sampling on the day prior to (–24 h; Day –1) through +168 h post lameness induction. Frequency of behaviour was analysed by day using generalised linear mixed model methods. The frequency of standing postures significantly decreased and lying postures increased 24–72 h post lameness induction relative to baseline day. All postures returned to baseline frequencies by +168 h. Meloxicam-treated sows demonstrated lower frequencies of lying postures +48 and +72 h after lameness induction compared to saline-treated sows. Flunixin-treated sows did not differ in lying behaviours compared to saline-treated sows. No differences were noted in standing or sitting postures between treatments. The results of this study suggest that meloxicam mitigates pain sensitivity as demonstrated by higher frequency of standing and lower frequency of lying compared to saline-treated sows.

Measuring the efficacy of flunixin meglumine and meloxicam for lame sows using nociceptive threshold tests

Lameness in breeding swine can cause severe pain leading to on-farm welfare issues and significant economic impacts. Non-steroidal anti-inflammatory drugs including meloxicam and flunixin meglumine are commonly used in veterinary medicine for their analgesic and anti-inflammatory properties. Pressure algometry and thermal sensitivity tests are non-invasive methods to quantify pain sensitivity using nociceptive thresholds to provoke withdrawal responses on lame and sound legs. The objective of this work was to determine the effects of these drugs on nociceptive thresholds in sows induced lame using pressure algometry and thermal sensitivity tests. Lameness was induced in 24 mature, mixed-parity sows using a chemical synovitis model and three treatments were compared: meloxicam (1.0 mg kg PO), flunixin meglumine (2.2 mg kg IM) and sterile saline (IM). Pressure algometry was measured on sound and lame rear legs with three replicates at three landmarks. Thermal sensitivity tests were done on sound and lame rear legs with three replicates using a thermal stimulus at one landmark. From 37 to 72 h after lameness induction, meloxicamand flunixin meglumine-treated sows tolerated higher pressure algometer nociceptive thresholds compared to saline-treated sows. Changes in thermal nociceptive thresholds were evident at the Tmax time-points for meloxicam administration and 72 and 168 h post lameness induction for flunixin meglumine-treated sows. In conclusion, flunixin meglumine and meloxicam administration mitigated pain sensitivity in lame sows post lameness induction when pain sensitivity was evaluated with pressure algometry. These analgesic drugs may be a key tool to manage pain associated with lameness.

Pharmacokinetics of meloxicam in mature swine after intravenous and oral administration

The purpose of this study was to compare the pharmacokinetics of meloxicam in mature swine after intravenous (i.v.) and oral (p.o.) administration. Six mature sows (mean bodyweight ± standard deviation = 217.3 ± 65.68 kg) were administered an i.v. or p.o. dose of meloxicam at a target dose of 0.5 mg/kg in a cross-over design. Plasma samples collected up to 48 h postadministration were analyzed by high-pressure liquid chromatography and mass spectrometry (HPLC-MS) followed by noncompartmental pharmacokinetic analysis. Mean peak plasma concentration (CMAX ) after p.o. administration was 1070 ng/mL (645-1749 ng/mL). TMAX was recorded at 2.40 h (0.50-12.00 h) after p.o. administration. Half-life (T½ λz ) for i.v. and p.o. administration was 6.15 h (4.39-7.79 h) and 6.83 h (5.18-9.63 h), respectively. The bioavailability (F) for p.o. administration was 87% (39-351%). The results of this study suggest that meloxicam is well absorbed after oral administration.

Sow behavioral responses to transient, chemically induced synovitis lameness

Abstract The objective was to determine behavioral changes when sows were induced lame using this chemical synovitis model. Twenty-three multiparous, non-pregnant sows were compared during lame and non-lame states. Behavior was recorded over three days. Seven behaviors (foraging, drinking, standing, sitting, sternal and lateral lying) and three locations (drinker, home pen and feed bunk) were recorded. Observations of sows drinking, standing, lying sternal and being in the drinker location decreased after induction. Lying lateral frequency, regardless of side, increased after sows were induced lame. Frequency in the home pen location increased, but no differences were observed for feed bunk location after sows were induced lame. The induced lame foot had no observed effect on lying side preference. By the end of the round, all behavioral and location frequencies returned to baseline levels. Standing, lying and drinking frequencies seem to be promising sow behavioral tools when transitioning from sound to lame states.

Development and refinement of a technique for short-term intravascular auricular vein catheter placement in mature sows.

Intravenous drug administration in adult swine is difficult to perform due to inaccessible superficial veins and thick subcutaneous fat layers. However, successful intravenous drug administration is critical for many biomedical applications including pharmacokinetic studies as extravascular drug administration can influence the drug’s absorption and elimination rate. The purpose of this study was to develop and refine an effective technique for indwelling auricular vein catheter placement in the conscious mature sow. We developed a protocol using a topical anesthetic cream and minimal physical restraint to place indwelling catheters in the auricular vein of six multiparous sows. This method was quick (3 min 20 s ± 8 s [mean ± SE per catheter]), effective (11/12 catheters successfully placed) and reliable, allowing a large drug volume (20–22 mL) to be administrated successfully during the trial without relying on prolonged restraint or general anesthesia of the sow.

Flooring preference and behavior in sound and lame sows

ABSTRACT The objectives of this study were to assess sow flooring preference and behavior during sound, induced lame and lameness recovery states. Thirty-four multiparous, non-pregnant sows were compared prior to and following lameness induction (day 0). Behavior was recorded on six days (days −1, +1, +2, +3, +4 and +10). Three flooring locations (Alley, Concrete and Mat) and four behaviors (lying lateral, lying sternal, sitting and standing) were recorded. Sows increased Mat frequency and decreased Alley frequency on day +1 (most lame) relative to day −1. Lying lateral frequency increased, whereas lying sternal and standing frequencies decreased between day −1 and day +1. Sows appear to prefer the Mat within 24 h following lameness induction. Lying lateral is likely a more comfortable position than standing or lying sternal in these lame sows. In conclusion, these behaviors may be reliable indicators to further ascertain if a sow is lame.