Physiologic Measures of Animal Stress during Transitional States of Consciousness

Meyer, Robert E.

doi:10.3390/ani5030380

Cited by 25 publications

(19 citation statements)

References 61 publications

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“…In light of this, the ongoing presence of slow wave EEG patterns in the early part of LAPS suggests an absence of stimulation as may be caused by pain or discomfort which would evoke a desynchronization of the EEG. Superimposed on the effects of darkness, the EEG response to LAPS was characterised by progressive domination of slow wave activity, with total power peaking at a time coinciding with loss of posture, a widely recognised proxy for loss of consciousness [10,19,39]. This shared latency, at around 60 s into LAPS, also matches the onset of prolonged reduced heart rates associated with unconsciousness [47].…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

Martin

Christensen

Vizzier-Thaxton

et al. 2016

Physiology & Behavior

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A novel approach to pre-slaughter stunning of chickens has been developed in which birds are rendered unconscious by progressive hypobaric hypoxia. Termed Low Atmospheric Pressure Stunning (LAPS), this approach involves application of gradual decompression lasting 280 s according to a prescribed curve. We examined responses to LAPS by recording behaviour, electroencephalogram (EEG) and electrocardiogram (ECG) in individual male chickens, and interpreted these with regards to the welfare impact of the process. We also examined the effect of two temperature adjusted pressure curves on these responses. Broiler chickens were exposed to LAPS in 30 triplets (16 and 14 triplets assigned to each pressure curve). In each triplet, one bird was instrumented for recording of EEG and ECG while the behaviour of all three birds was observed. Birds showed a consistent sequence of behaviours during LAPS (ataxia, loss of posture, clonic convulsions and motionless) which were observed in all birds. Leg paddling, tonic convulsions, slow wing flapping, mandibulation, head shaking, open bill breathing, deep inhalation, jumping and vocalisation were observed in a proportion of birds. Spectral analysis of EEG responses at 2 s intervals throughout LAPS revealed progressive decreases in median frequency at the same time as corresponding progressive increases in total power, followed later by decreases in total power as all birds exhibited isoelectric EEG and died. There was a very pronounced increase in total power at 50-60 s into the LAPS cycle, which corresponded to dominance of the signal by high amplitude slow waves, indicating loss of consciousness.Slow wave EEG was seen early in the LAPS process, before behavioural evidence of loss of consciousness such as ataxia and loss of posture, almost certainly due to the fact that it was completely dark in the LAPS chamber. ECG recordings showed a pronounced bradycardia (starting on average 49.6 s into LAPS), often associated with arrhythmia, until around 60 s into LAPS when heart rate levelled off. There was a good correlation between behavioural, EEG and cardiac measures in relation to loss of consciousness which collectively provide a loss of consciousness estimate of around 60 s. There were some effects of temperature A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTadjusted pressure curves on behavioural latencies and ECG responses, but in general responses were consistent and very similar to those reported in previous research on controlled atmosphere stunning with inert gases. The results suggest that the process is humane (slaughter without avoidable fear, anxiety, pain, suffering and distress). In particular, the maintenance of slow wave EEG patterns in the early part of LAPS (while birds are still conscious) is strongly suggestive that LAPS is non-aversive, since we would expect this to be interrupted by pain or discomfort. Highlights A novel stunning system uses hypobaric hypoxia to render poultry unconscious  We measured electroencephalogram, electrocardiogram and...

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

Martin

Christensen

Vizzier-Thaxton

et al. 2016

Physiology & Behavior

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“…The presence of cardiac electrical activity does not imply effective cardiac pumping because the ECG is only a 2-D recording at the body surface of electrical fields generated by the heart, and it does not reflect the mechanical status of the heart. 8,15 The time from initiation of euthanasia to apnea in birds was short (median time, ≤ 26 seconds for sparrows and ≤ 12.5 seconds for starlings) for both euthanasia methods in the present study, with no significant differences between methods for either species. In mammals, barbiturates depress the CNS beginning with the cerebral cortex, resulting in loss of consciousness that progresses to anesthesia.…”

Section: Discussionmentioning

confidence: 55%

“…The use of EEG activity to determine when consciousness is lost is considered by some investigators to be the most objective means of assessing unconsciousness, 6,7 while others believe that the EEG is not a direct measure of consciousness and does not determine the exact moment when unconsciousness occurs because changes can be gradual and subtle. 8 However, there is sufficient agreement that an isoelectric EEG pattern (also known as a flatline pattern or electrocerebral inactivity) is not compatible with consciousness and is an indicator of cessation of normal cerebral function. 6 Electroencephalography results have been used in welfare evaluations of poultry slaughter and euthanasia techniques.…”

Section: Eegmentioning

confidence: 99%

Comparison of intraosseous pentobarbital administration and thoracic compression for euthanasia of anesthetized sparrows (Passer domesticus) and starlings (Sturnus vulgaris)

Paul-Murphy¹,

Engilis

Pascoe

et al. 2017

ajvr

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OBJECTIVE To compare intraosseous pentobarbital treatment (IPT) and thoracic compression (TC) on time to circulatory arrest and an isoelectric electroencephalogram (EEG) in anesthetized passerine birds. ANIMALS 30 wild-caught adult birds (17 house sparrows [Passer domesticus] and 13 European starlings [Sturnus vulgaris]). PROCEDURES Birds were assigned to receive IPT or TC (n = 6/species/group). Birds were anesthetized, and carotid arterial pulses were monitored by Doppler methodology. Five subdermal braided-wire electrodes were used for EEG. Anesthetic depth was adjusted until a continuous EEG pattern was maintained, then euthanasia was performed. Times from initiation of euthanasia to cessation of carotid pulse and irreversible isoelectric EEG (indicators of death) were measured. Data (medians and first to third quartiles) were summarized and compared between groups within species. Necropsies were performed for all birds included in experiments and for another 6 birds euthanized under anesthesia by TC (4 sparrows and 1 starling) or IPT (1 sparrow). RESULTS Median time to isoelectric EEG did not differ significantly between treatment groups for sparrows (19.0 and 6.0 seconds for TC and IPT, respectively) or starlings (88.5 and 77.5 seconds for TC and IPT, respectively). Median times to cessation of pulse were significantly shorter for TC than for IPT in sparrows (0.0 vs 18.5 seconds) and starlings (9.5 vs 151.0 seconds). On necropsy, most (14/17) birds that underwent TC had grossly visible coelomic, pericardial, or perihepatic hemorrhage. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that TC might be an efficient euthanasia method for small birds. Digital pressure directly over the heart during TC obstructed venous return, causing rapid circulatory arrest, with rupture of the atria or vena cava in several birds. The authors propose that cardiac compression is a more accurate description than TC for this procedure.

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“…It is of course a limitation that the current study was carried out in anaesthetized animals, but it was considered impossible to implement a similar protocol in conscious animals, particularly in mice (because of ethical concerns). In addition, the handling of conscious animals is associated with considerable stress (17), which was avoided by our protocol. On the other hand, the anesthesia itself may influence the autonomic nervous system.…”

Section: Discussionmentioning

confidence: 99%

Dynamics of glucagon secretion in mice and rats revealed using a validated sandwich ELISA for small sample volumes

Albrechtsen

Kuhre

Windeløv

et al. 2016

American Journal of Physiology-Endocrinology and Metabolism

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Wewer Albrechtsen NJ, Kuhre RE, Windeløv JA, Ørgaard A, Deacon CF, Kissow H, Hartmann B, Holst JJ. Dynamics of glucagon secretion in mice and rats revealed using a validated sandwich ELISA for small sample volumes. Am J Physiol Endocrinol Metab 311: E302-E309, 2016. First published May 31, 2016 doi:10.1152/ajpendo.00119.2016.-Glucagon is a metabolically important hormone, but many aspects of its physiology remain obscure, because glucagon secretion is difficult to measure in mice and rats due to methodological inadequacies. Here, we introduce and validate a low-volume, enzyme-linked immunosorbent glucagon assay according to current analytical guidelines, including tests of sensitivity, specificity, and accuracy, and compare it, using the BlandAltman algorithm and size-exclusion chromatography, with three other widely cited assays. After demonstrating adequate performance of the assay, we measured glucagon secretion in response to intravenous glucose and arginine in anesthetized mice (isoflurane) and rats (Hypnorm/midazolam). Glucose caused a long-lasting suppression to very low values (1-2 pmol/l) within 2 min in both species. Arginine stimulated secretion 8-to 10-fold in both species, peaking at 1-2 min and returning to basal levels at 6 min (mice) and 12 min (rats). D-Mannitol (osmotic control) was without effect. Ketamine/xylazine anesthesia in mice strongly attenuated (P Ͻ 0.01) ␣-cell responses. Chromatography of pooled plasma samples confirmed the accuracy of the assay. In conclusion, dynamic analysis of glucagon secretion in rats and mice with the novel accurate sandwich enzyme-linked immunosorbent assay revealed extremely rapid and short-lived responses to arginine and rapid and profound suppression by glucose.␣-cell; islet biology; immunoassay; enzyme-linked immunosorbent assay GLUCAGON REGULATES BLOOD GLUCOSE by stimulating hepatic glucose production (3). Importantly, elevated fasting and postprandial glucagon levels in patients with type 2 diabetes contribute to the hyperglycemia of these patients as demonstrated clearly using specific antagonists of the glucagon receptor (13). However, regulation of glucagon secretion has only been incompletely characterized, due partly to technical limitations with regard to its quantification (volume requirements, inadequate specificity, and accuracy) using current immune-based detection methods: radioimmunoassay (RIA) and enzyme-linked immunosorbent assays (ELISA) (7,8,16,18,22).Here, we introduce a novel low-volume sandwich ELISA that exclusively detects fully processed pancreatic glucagon, corresponding to proglucagon-(33-61) (see Fig. 1), and use it to characterize the dynamics of glucagon secretion in mice and rats in response to intravenous injections of L-arginine, D-glucose, and D-mannitol. By extensive assay validation, we conclude that the applied assay is reliable for measurements of glucagon in small plasma volumes. Because of this technical advance, we were able to make reliable real-time estimates of glucagon secretion (in vivo) in mice and rats. Our...

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Physiologic Measures of Animal Stress during Transitional States of Consciousness

Cited by 25 publications

References 61 publications

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

Comparison of intraosseous pentobarbital administration and thoracic compression for euthanasia of anesthetized sparrows (Passer domesticus) and starlings (Sturnus vulgaris)

Dynamics of glucagon secretion in mice and rats revealed using a validated sandwich ELISA for small sample volumes

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