For zebrafish, the hypothermia should involve immersion in ice water, rapidly inducing cold shock. Specialized physical methods that may be acceptable include microwave irradiation of small rodents using specialized equipment and hypothermia of some poikilotherms (altricial rodents as well as zebrafish). The AVMA lists decapitation as acceptable as a sole agent in neonatal mammals and birds. Although this is the basis for special concern in the use of CO 2 for their euthanasia, similar concern over decapitation of these animals has not been raised. Neonatal rodents and birds are likewise resistant to the effects of cerebral hypoxia. The Guidelines recommend prior sedation, followed by pithing, which will rapidly destroy brain centers that could sustain consciousness. Best practice for animal welfare is to require training on cadavers or on anesthetized animals ( Carbone et al., 2012 AVMA Panel on Euthanasia, 2013).ĭecapitation is not ideal as sole method in species, such as reptiles and amphibians, in which the central nervous system may be relatively insensitive to cerebral hypoxia. These methods, along with other physical methods that destroy brain centers (such as captive bolt), may require more training and skill than turning on a CO 2 flow meter, and carry high welfare consequences if done incorrectly, and thus they are “acceptable with conditions”. Rather, decapitation and cervical dislocation are considered acceptable with conditions for some small animals (rodents, small rabbits, small birds), the conditions and the primary concerns being operator skill. Since that report, the 2000, 2007, and 2013 reports have acknowledged uncertainty about the precise significance of this brain activity but have not based recommendations on concern that the brain activity implies consciousness. That panel prescribed light sedation, or post-decapitation freezing of the brain, as a precautionary response to the uncertainty of what the brain waves might signify. The 1986 AVMA Panel rated physical methods such as decapitation and cervical dislocation “acceptable with prior sedation or light anesthesia” based on postmortem brain wave activity seen in decapitated rats. Larry Carbone, in Laboratory Animal Welfare, 2014 Physical Methods Care must be taken during delivery of the head that sharp bony protrusions of the cervical spine do not injure the maternal tissues. The head is steadied by applying suprapubic pressure and can usually be delivered by finger traction through the baby’s mouth, or by the application of forceps, or by using vulsellum or other toothed forceps on the fetal scalp. After the head is completely severed the trunk is removed by traction on the arm ( Fig. This technique is much safer, simpler and less traumatic to the maternal tissues than the previously used decapitation hooks. 42.4, and by a to-and-fro motion the neck is severed. The ends of the wire are now mounted on the handles shown in Fig. The middle finger feels for the metal loop that projects from the thimble and, having secured it, pulls the thimble with the attached wire off the thumb and round the fetal neck ( Fig. The thumb with the thimble is passed in front of the fetal neck and the fingers behind. If there is a prolapsed arm, counter-traction is put on this to make the fetal neck accessible. The operator mounts the thimble on one thumb and attaches the wire to the slot in the thimble. The safest and most simple technique is to use a Blond–Heidler saw ( Fig. In this situation the alternative of internal version or breech extraction carries a high risk of uterine rupture and is contraindicated. It is indicated in cases of neglected labour with a dead fetus in transverse lie with a prolapsed arm or shoulder presentation. Of all the procedures outlined in this chapter, decapitation is the most distressing for all involved. Sri Sabaratnam Arulkumaran KB MB BS (University of Ceylon), PhD DSc FRCS FRCOG, in Munro Kerr's Operative Obstetrics, 2020 Decapitation
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