The use of carbon dioxide (CO2) as an alternative euthanasia method for goat kids

Abstract

The dairy industry is faced with the challenge of euthanizing unwanted male offspring in addition to other sick or injured neonates. Carbon dioxide (CO2) may be a potential alternative to current methods. The goat kid served as a model in approachavoidance and conditioned place aversion paradigms. A preference test box was custommade with two connected chambers; one chamber held an ambient atmosphere (control) and one maintained a static CO2 concentration (treatment). Kids were allotted 5-minutes in the control chamber before a sliding door was opened, after which kids were given 10minutes access to the treatment chamber. The objective of the first study was to determine the ability of kids to move from the control to the treatment chamber to access a milk reward, and the effect of an olfactory or visual stimulus on learning. All kids (n=24) exhibited learning, and latencies to enter, touch the milk bottle, and suckle decreased over day (P<0.0001). Milk consumption increased over days (P<0.0001), and startle, bottle engagement, and lying behavior did not differ between days (P>0.05). The presence of an olfactory stimulus (peppermint oil) did not affect learning, and the visual stimulus (plastic curtain) did not prevent learning. The second study examined kids' tolerance of 10%, 20%, and 30% CO2. Kids (n=12) were randomly assigned 10% or 20% as the first treatment, and were systematically tested with all kids receiving 30% as the last treatment. A 2-day washout (ambient CO2) period occurred between each gas treatment. 10 kids tolerated 10% CO2, while one kid exited the treatment chamber after consuming his full ration, and 1 kid lost posture at 289s. At 20% and 30%, posture loss ranged from 83s to 271s. One kid exited before losing posture at 20%, then re-entered the chamber and became recumbent. Kids did not show avoidance behavior to any CO2 ix concentration, and did not appear to develop a conditioned aversion. The results of this study show promising results for CO2 as a euthanasia method in goat kids. Further research is required to confirm its suitability, and determine its potential for other ruminant species.

Verantwoorde omgang met zorgbehoevende dieren en euthanasie op het primaire bedrijf

“…Hierbij werd er weinig tot geen verschil gevonden in het snel dan wel gradueel vullen van de gasbox met CO2 bij konijnen in aversie, tekenen van stress of gedragsveranderingen. Withrock (2015) onderzocht het gebruik van gas bij jonge geitjes, waarbij voornamelijk gekeken werd naar de aversie reactie van de geitjes op gasconcentraties. Uit dit onderzoek bleek dat CO2 uitermate geschikt is voor het doden van jonge geitjes waarbij ze geen ontwijkingsgedrag vertonen bij blootstelling en gemakkelijk terugkeren naar de gasbox ook al wordt er een keuze geboden.…”

Perspectives for Buck Kids in Dairy Goat Farming

“…Carbon dioxide challenge is used to provoke panic attacks in human research settings and may produce anxiety and pain before inducing anesthesia (62,63). However, in goat kids undergoing reversible carbon dioxide anesthesia in concentrations up to 30%, it did not cause spontaneous aversion or conditioned place aversion (64). It may therefore be a suitable method to stun kids.…”

Behavioral and corticosterone responses to carbon dioxide exposure in reptiles

“…Carbon dioxide (CO 2 ) is widely used as a euthanizing agent in the livestock industry and for scientific research [2,[8][9][10]. The guidelines of the American Veterinary Medical Association cite 86 studies on the effectiveness and suitability of CO 2 as a humane means of euthanasia for mammals and birds [2].…”

“…The guidelines of the American Veterinary Medical Association cite 86 studies on the effectiveness and suitability of CO 2 as a humane means of euthanasia for mammals and birds [2]. Mammalian and avian responses to CO 2 exposure vary considerably by species, and are dependent on CO 2 concentration and delivery method [2,[8][9][10]. Mice, rats, cats, dogs, pigs, rabbits, chickens, and turkeys lose consciousness after 20-120 seconds of CO 2 exposure, but may require exposures of 5-50 minutes to ensure death [2,9,10].…”

“…Exposure to CO 2 has been shown to increase plasma corticosterone levels in rats and dogs and results in mouth gaping in mice, rats, and chickens [2,9]. Rats and mink will actively avoid CO 2 exposure if given the opportunity, but goats and chickens will not (despite the latter gaping when exposed; [2,8]).…”