Characterisation of the Behavioural Effects of a Thoracic Squeeze in Healthy Newborn Piglets

Abstract

A thoracic squeeze has been observed to cause both healthy and low vigour neonatal foals to enter a ‘less-responsive state’, characterised by loss of posture, eye closure and cessation of movement, from which they rapidly recover to express normal healthy behaviours when the squeeze is released. To date, there have been no systematic studies characterising the responses of healthy neonates of other mammalian species to a thoracic squeeze. We describe the responses of healthy newborn piglets (n = 17) to a standardised application of the thoracic squeeze and evaluate the effect of the method of squeeze application on the response. Neonatal piglets were squeezed around the chest with either a soft fabric rope as has been used in foals (n = 8) or a novel purpose-made inflation cuff (n = 9). Both methods were effective at inducing a less-responsive behavioural state in all piglets, with neural reflexes reduced or absent in over half of them. The inflation cuff appeared to induce the less-responsive state faster than the rope, and more piglets squeezed with the cuff remained in this state for the full 10-min squeeze. These findings suggest that the behavioural response of foals to thoracic squeezing can be generalised to neonates of other precocial mammalian species. This initial study provides a foundation for further research using the inflation cuff to explore mechanisms underlying the thoracic squeeze and ways in which it may be applied whilst performing husbandry procedures.

Evaluating the Behavioural Responses of Healthy Newborn Calves to a Thoracic Squeeze

“…They were assessed for inclusion in the study at 12 to 36 h old. In total, sixteen healthy calves (6 Jersey, 10 Friesian crossbreed) were selected based on the following inclusion criteria (as described in detail by Holdsworth et al [ 14 ]): normal locomotion, sucking reflex, body posture, respiratory rate, heart rate, and rectal temperature. In order to assess locomotion, the calves were encouraged to stand through touch or by manually assisting the calf to its feet, and their movement around the pen was observed.…”

“…The calf was held by a handler with one arm supporting the hind end and one arm around the front of the chest to keep the calf in a standing position. The squeeze device was firmly secured around the thorax, and the squeeze was applied as described by Holdsworth et al [ 14 ]. A timer was started upon the application of the squeeze, and the latency to induction into a state of reduced responsiveness was recorded by identifying two behaviours: lateral recumbency and the cessation of limb movements.…”

“…The squeeze was applied until the calf met the discontinuation criteria (see Section 2.4 below) or the maximum time of 10 min was reached. Prior research in pigs has demonstrated that 10 min is sufficient to demonstrate squeeze efficacy [ 14 ]. Furthermore, this is shorter than the average duration of stage II labour in cows (38–114 min [ 17 , 18 , 19 ]), ensuring that any risks associated with prolonged squeezing were mitigated.…”

“…Furthermore, this is shorter than the average duration of stage II labour in cows (38–114 min [ 17 , 18 , 19 ]), ensuring that any risks associated with prolonged squeezing were mitigated. After the squeeze was completed or discontinued, each calf was monitored for 5 min in order to ensure that they had recovered from the squeeze and were displaying the behaviours described in the inclusion criteria [ 14 ]. The calves were encouraged into sternal recumbency, and were allowed to remain there for two minutes before being encouraged to stand by a researcher in order to assess their recovery.…”

“…A small loop was already sewn into one end of the rope, which acted as a bowline knot. The rope squeeze was applied as described by Holdsworth et al [ 14 ] ( Figure 1 ).…”