Thermal nociceptive threshold testing detects altered sensory processing in broiler chickens with spontaneous...

Area of Science:

• Animal Science
• Veterinary Medicine
• Pain Research

Background:

• Lameness is prevalent in commercial broiler chickens, impacting welfare.
• Understanding the relationship between lameness, pain, and bird welfare is complex.
• Thermal nociceptive threshold (TNT) testing offers insight into pain processing.

Purpose of the Study:

• To investigate factors influencing thermal nociceptive threshold (TNT) in commercial broiler chickens.
• To evaluate the effects of meloxicam (NSAID) and butorphanol (opioid) on TNT in lame and non-lame birds.
• To extend previous findings on TNT in experimentally induced lameness to a commercial setting.

Main Methods:

• Studied 167 spontaneously lame and matched non-lame commercial broiler chickens.
• Utilized thermal ramp stimulation on the tarsometatarsus to determine nociceptive thresholds.
• Administered meloxicam (5 mg/kg) or butorphanol (4 mg/kg) subcutaneously and assessed threshold changes.

Main Results:

• Lameness significantly increased thermal nociceptive threshold after accounting for other factors.
• Meloxicam differentially affected threshold: increasing it in lame birds and decreasing it in non-lame birds.
• Baseline skin temperature was a significant predictor of threshold; butorphanol had no detectable effect.

Conclusions:

• Lameness alters nociceptive processing in broiler chickens, contrary to initial hypotheses.
• The differential effect of meloxicam suggests complex pain modulation in lame birds.
• Further research is needed to elucidate the mechanisms underlying these altered nociceptive responses.