Onset of sentience: The potential for suffering in fetal and newborn farm animals

Mellor, D. J.; Diesch, Tamara

doi:10.1016/j.applanim.2006.04.012

Cited by 83 publications

(88 citation statements)

References 45 publications

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“…Recent evaluations of published evidence suggest that under normal circumstances sheep fetuses probably do not exhibit awareness or consciousness before birth (Mellor and Gregory 2003;Mellor et al 2005;Mellor and Diesch 2006) and therefore that awareness normally appears for the fi rst time only after birth (Mellor and Gregory 2003;Mellor and Diesch 2006). The neuroanatomical and neurophysiological development of the embryo and fetus and unique features of the physiological environment of the fetal brain, features which are lost at birth, have been suggested as an explanation for this phenomenon.…”

Section: Introductionmentioning

confidence: 95%

Birth and hatching: Key events in the onset of awareness in the lamb and chick

Mellor¹,

Diesch²

2007

New Zealand Veterinary Journal

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The neuroanatomical and neurophysiological development of the embryo and fetus and unique features of the physiological environment of the fetal brain, features which are lost at birth, support recent conclusions that under normal circumstances awareness (or consciousness) is probably not exhibited by the ovine embryo-fetus before birth and that it appears for the first time only after birth. However, there has apparently been no evaluation of whether or not similar mechanisms modulate awareness-related functions in domestic chicks before and after hatching. This comparative review, in seeking to rectify this, arrived at the following conclusions. First, the neural apparatus of both lambs and chicks appears to be too immature to support any states resembling awareness during at least the first half of pregnancy or incubation. Second, electroencephalographic (EEG) activity, which evolves subsequently, shows that states of sleep-like unconsciousness are likely to be continuously present in lambs until after birth, and that such states at least predominate in chicks until after hatching. Third, as in fetal lambs, epochs of so-called 'wakefulness' previously reported in chick embryos do not seem likely to represent short periods of awareness in ovo. Fourth, several neurosuppressive mechanisms, with some unique features, also operate or have the potential to operate in chicks before hatching, but a dearth of published information currently hinders a full comparison with those demonstrated to operate in fetal lambs. Fifth, contradicting the intuitive perception that vocalisation pre-hatching by the chick indicates the presence of awareness, published evidence suggests that vocalisation before and during hatching occurs mostly during EEG states indicating sleep-like unconsciousness. Sixth, as seems to be the case for newborn lambs after birth, it is possible that demonstrable awareness may appear for the first time only after hatching in chicks, presumably through waning neurosuppression and burgeoning neuroactivation, but such awareness seems to take longer to manifest itself. However, additional research in chicks is recommended to further assess this suggestion. Particular attention should be given to the status of vocal interactions between hen and chick which begin several days before hatching, and to the operation of neurosuppressive and neuroactivating mechanisms throughout the last 40% of incubation and during and after hatching.

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Section: Introductionmentioning

confidence: 95%

Birth and hatching: Key events in the onset of awareness in the lamb and chick

Mellor¹,

Diesch²

2007

New Zealand Veterinary Journal

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“…However, farm animals appear to be able to suffer soon after birth, when breathing oxygenates the newborn sufficiently to remove the inhibition of pain functions of the brain (Mellor and Diesch, 2006). In this sense, foals of between 1 week and 6 months perceive and respond to both superficial and deep cutaneous painful stimulation, suggesting the necessity to anaesthetise them at the time of an operation (Dunlop, 1994).…”

Section: Cosmetic Aspectsmentioning

confidence: 99%

Tail docking in horses: a review of the issues

Lefebvre¹,

Lips

Ödberg

et al. 2007

Animal

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Routinely performed painful procedures are of increasing interest and, in 2001 (Royal Order, May 17), Belgium prohibited docking in several vertebrates including horses. In 2004, opponents to this decision submitted a Bill (Doc51 0969/001) to Parliament, intending to obtain derogation for Belgian draught horses, which were traditionally docked. The Animal Welfare Council of Belgium, an official body advising the Minister of Public Health, was asked to evaluate this complex question, including biological, ethical and socio-economic aspects, on the basis of the available peer-reviewed studies. In this context, this study reviews legal aspects (overview of the European legislation), zootechnic aspects (uses of the Belgian draught horse) and biological aspects (pain potentially related to docking; horses’ welfare linked to insect harassment and hygiene, communication and reproduction) of tail docking in draught horses. We conclude that (1) there is no benefit for horses in tail docking, including Belgian draught horses, (2) potential advantages of docking are essentially in favour of humans and these advantages could be scrupulously re-evaluated, taking into account practices of other countries. Therefore, there is no need to dock any horse other than for veterinary reasons.

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“…At one extreme the neonates of a number of species, which include cattle, deer, goats, sheep and horses, are neurologically mature at birth and exhibit the behavioural and physiological signs indicative of conscious responses to sensory inputs within minutes or hours of birth. 3,13,14 The young of other species, which include rats, mice, rabbits, cats and dogs are neurologically relatively immature, 12 and the onset of consciousness and the ability to perceive sensations is apparently delayed for several days. In rat pups, for example, postnatal development of the behavioural repertoire, the EEG and the EEG responses to noxious stimuli, together suggest that pups are not likely to perceive pain during the first week after birth, and that the ability to perceive pain develops gradually between postnatal ages 12 -14 days and 21 -22 days.…”

mentioning

confidence: 99%

“…its nervous system must be sufficiently developed to relay sensory inputs to the higher centres of the brain, including the cerebral cortex, for appropriate interpretation. 3,4 Secondly, the brain must be functionally capable of inducing consciousness, as this is a prerequisite for the animal to experience any sensation including pain. 5 There is evidence that the cerebral cortex is involved in the human experience of pain perception.…”

mentioning

confidence: 99%

Developmental changes in the electroencephalogram and responses to a noxious stimulus in anaesthetized tammar wallaby joeys (Macropus eugenii eugenii)

Diesch

Mellor²,

Johnson

et al. 2010

Lab Anim

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The tammar wallaby joey is born extremely immature and most of its neurological development occurs in the maternal pouch. It is not known at what in-pouch age functions such as conscious sensory perception commence. We determined the electroencephalographic (EEG) responses to noxious stimulation in lightly anaesthetized tammar wallaby joeys. Baseline median (F50) and spectral edge (F95) frequencies, total power (Ptot) and frequency spectra between 1 and 30 Hz of the EEG power spectrum were determined. Joeys aged less than 127 days showed little or no EEG activity. Prolonged periods of spontaneous EEG activity were present by 142 days. This activity increased, as did the power in all frequencies, while the duration of any intervening isoelectric periods decreased with increasing in-pouch age. EEG responses to a noxious stimulus (toe clamping) changed with increasing in-pouch age as there was no response from joeys aged 94-127 days (no EEG), a minimal decrease in the F50 in those aged between 142 and 181 days (P ¼ 0.052) and a greater decrease in the F50 in those aged between 187 and 261 days (P , 0.001). The pattern of these changes, which presumably reflects anatomical and functional maturation of the cerebral cortex, is similar to, but develops more slowly than, that reported in the rat. The opening of the eyes and development of the pelage are discussed as markers of when brain development may be sufficient for joeys to consciously perceive noxious sensations including pain.

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Onset of sentience: The potential for suffering in fetal and newborn farm animals

Cited by 83 publications

References 45 publications

Birth and hatching: Key events in the onset of awareness in the lamb and chick

Birth and hatching: Key events in the onset of awareness in the lamb and chick

Tail docking in horses: a review of the issues

Developmental changes in the electroencephalogram and responses to a noxious stimulus in anaesthetized tammar wallaby joeys (Macropus eugenii eugenii)

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