Characterizing candidate decompression rates for hypobaric hypoxic stunning of pigs. Part 2: Pathological...

Area of Science:

• Veterinary Pathology
• Animal Welfare Science
• Food Science

Background:

• Carbon dioxide stunning in pigs raises welfare concerns.
• Low Atmospheric Pressure Stunning (LAPS) via gradual decompression is a potential welfare-friendly alternative.
• Feasibility and welfare implications of LAPS in pigs remain uncharacterized.

Purpose of the Study:

• To characterize pathological changes in pigs exposed to varying gradual decompression rates.
• To identify potential candidate rate profiles for future LAPS stunning methods in pigs.
• To inform discussions on carcass quality implications of LAPS.

Main Methods:

• Sixty terminally anesthetized pigs were exposed to a range of decompression curves (40-100 ms⁻¹ ascent equivalent; 480s and 720s cycle durations).
• Detailed post-mortem examinations were conducted by a specialized porcine veterinary pathologist.
• Pathological changes, including congestion and hemorrhage, were systematically scored across various organs and body cavities.

Main Results:

• All pigs died due to decompression, showing no external ante-mortem injuries.
• Generalized congestion and hemorrhage were observed across multiple organs and body cavities.
• Faster decompression rates generally correlated with higher scores for congestion and hemorrhage, with some exceptions.

Conclusions:

• Gradual decompression causes significant pathological changes in pigs, including congestion and hemorrhage.
• The observed pathological findings suggest potential welfare harms if applied to conscious pigs.
• This study provides foundational pathological data for developing LAPS as a pig stunning method and assessing its carcass quality impact.