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Carroll, G. L., Matthews, N. S., Hartsfield, S. M., Slater, M. R., Champney, T. H., & Erickson, S. W. (1997). The effect of detomidine and its antagonism with tolazoline on stress-related hormones, metabolites, physiologic responses, and behavior in awake ponies. Vet Surg, 26(1), 69–77.
Abstract: Six ponies were used to investigate the effect of tolazoline antagonism of detomidine on physiological responses, behavior, epinephrine, norepinephrine, cortisol, glucose, and free fatty acids in awake ponies. Each pony had a catheter inserted into a jugular vein 1 hour before beginning the study. Awake ponies were administered detomidine (0.04 mg/kg intravenously [i.v.]) followed 20 minutes later by either tolazoline (4.0 mg/kg i.v.) or saline. Blood samples were drawn from the catheter 5 minutes before detomidine administration (baseline), 5 minutes after detomidine administration, 20 minutes before detomidine administration which was immediately before the administration of tolazoline or saline (time [T] = 0), and at 5, 30, and 60 minutes after injections of tolazoline or saline (T = 5, 30, and 60 minutes, respectively). Compared with heart rate at T = 0, tolazoline antagonism increased heart rate 45% at 5 minutes. There was no difference in heart rate between treatments at 30 minutes. Blood pressure remained stable after tolazoline, while it decreased over time after saline. Compared with concentrations at T = 0, tolazoline antagonism of detomidine in awake ponies resulted in a 55% increase in cortisol at 30 minutes and a 52% increase in glucose at 5 minutes. The change in free fatty acids was different for tolazoline and saline over time. Free fatty acids decreased after detomidine administration. Free fatty acids did not change after saline administration. After tolazoline administration, free fatty acids increased transiently. Tolazoline tended to decrease sedation and analgesia at 15 and 60 minutes postantagonism. Antagonism of detomidine-induced physiological and behavioral effects with tolazoline in awake ponies that were not experiencing pain appears to precipitate a stress response as measured by cortisol, glucose, and free fatty acids. If antagonism of an alpha-agonist is contemplated, the potential effect on hormones and metabolites should be considered.
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Crook, J. H. (1983). On attributing consciousness to animals. Nature, 303(5912), 11–14.
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Doherty, T. J., & Frazier, D. L. (1998). Effect of intravenous lidocaine on halothane minimum alveolar concentration in ponies. Equine Vet J, 30(4), 300–303.
Abstract: This study investigated the effect of lidocaine i.v. on halothane minimum alveolar concentration (MAC) in ponies. Six ponies were anaesthetised with thiopentone and succinylcholine, intubated and anaesthesia maintained with halothane. Ventilation was controlled and blood pressure maintained within clinically acceptable limits. Following a 2 h equilibration period, baseline halothane MAC was determined. The ponies were then given a loading dose of lidocaine (2.5 or 5 mg/kg bwt) or saline over 5 min, followed by a constant infusion of lidocaine (50 or 100 microg/kg/min, or saline, respectively). The halothane MAC was redetermined after a 60 min infusion of lidocaine or saline. The baseline halothane MAC for the control group was mean +/- s.d. 0.94 +/- 0.03%, and no significant decrease occurred following saline infusion. Lidocaine decreased halothane MAC in a dose-dependent fashion (r = 0.86; P < 0.0003). The results indicate that i.v. lidocaine may have a role in equine anaesthesia.
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Forster, H. V., Pan, L. G., Bisgard, G. E., Flynn, C., & Hoffer, R. E. (1985). Changes in breathing when switching from nares to tracheostomy breathing in awake ponies. J Appl Physiol, 59(4), 1214–1221.
Abstract: We assessed the consequences of respiratory unloading associated with tracheostomy breathing (TBr). Three normal and three carotid body-denervated (CBD) ponies were prepared with chronic tracheostomies that at rest reduced physiological dead space (VD) from 483 +/- 60 to 255 +/- 30 ml and lung resistance from 1.5 +/- 0.14 to 0.5 +/- 0.07 cmH2O . l-1 . s. At rest and during steady-state mild-to-heavy exercise arterial PCO2 (PaCO2) was approximately 1 Torr higher during nares breathing (NBr) than during TBr. Pulmonary ventilation and tidal volume (VT) were greater and alveolar ventilation was less during NBr than TBr. Breathing frequency (f) did not differ between NBr and TBr at rest, but f during exercise was greater during TBr than during NBr. These responses did not differ between normal and CBD ponies. We also assessed the consequences of increasing external VD (300 ml) and resistance (R, 0.3 cmH2O . l-1 . s) by breathing through a tube. At rest and during mild exercise tube breathing caused PaCO2 to transiently increase 2-3 Torr, but 3-5 min later PaCO2 usually was within 1 Torr of control. Tube breathing did not cause f to change. When external R was increased 1 cmH2O . l-1 . s by breathing through a conventional air collection system, f did not change at rest, but during exercise f was lower than during unencumbered breathing. These responses did not differ between normal, CBD, and hilar nerve-denervated ponies, and they did not differ when external VD or R were added at either the nares or tracheostomy.(ABSTRACT TRUNCATED AT 250 WORDS)
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Gallup, G. G. J. (1985). Do minds exist in species other than our own? Neurosci Biobehav Rev, 9(4), 631–641.
Abstract: An answer to the question of animal awareness depends on evidence, not intuition, anecdote, or debate. This paper examines some of the problems inherent in an analysis of animal awareness, and whether animals might be aware of being aware is offered as a more meaningful distinction. A framework is presented which can be used to make a determination about the extent to which other species have experiences similar to ours based on their ability to make inferences and attributions about mental states in others. The evidence from both humans and animals is consistent with the idea that the capacity to use experience to infer the experience of others is a byproduct of self-awareness.
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Griffin, D. R. (1998). From cognition to consciousness. Anim. Cogn., 1(1), 3–16.
Abstract: This paper proposes an extension of scientific horizons in the study of animal behavior and cognition to include conscious experiences. From this perspective animals are best appreciated as actors rather than passive objects. A major adaptive function of their central nervous systems may be simple, but conscious and rational, thinking about alternative actions and choosing those the animal believes will get what it wants, or avoid what it dislikes or fears. Versatile adjustment of behavior in response to unpredictable challenges provides strongly suggestive evidence of simple but conscious thinking. And especially significant objective data about animal thoughts and feelings are already available, once communicative signals are recognized as evidence of the subjective experiences they often convey to others. The scientific investigation of human consciousness has undergone a renaissance in the 1990s, as exemplified by numerous symposia, books and two new journals. The neural correlates of cognition appear to be basically similar in all central nervous systems. Therefore other species equipped with very similar neurons, synapses, and glia may well be conscious. Simple perceptual and rational conscious thinking may be at least as important for small animals as for those with large enough brains to store extensive libraries of behavioral rules. Perhaps only in “megabrains” is most of the information processing unconscious.
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Griffin, D. R., & Speck, G. B. (2004). New evidence of animal consciousness. Anim. Cogn., 7(1), 5–18.
Abstract: This paper reviews evidence that increases the probability that many animals experience at least simple levels of consciousness. First, the search for neural correlates of consciousness has not found any consciousness-producing structure or process that is limited to human brains. Second, appropriate responses to novel challenges for which the animal has not been prepared by genetic programming or previous experience provide suggestive evidence of animal consciousness because such versatility is most effectively organized by conscious thinking. For example, certain types of classical conditioning require awareness of the learned contingency in human subjects, suggesting comparable awareness in similarly conditioned animals. Other significant examples of versatile behavior suggestive of conscious thinking are scrub jays that exhibit all the objective attributes of episodic memory, evidence that monkeys sometimes know what they know, creative tool-making by crows, and recent interpretation of goal-directed behavior of rats as requiring simple nonreflexive consciousness. Third, animal communication often reports subjective experiences. Apes have demonstrated increased ability to use gestures or keyboard symbols to make requests and answer questions; and parrots have refined their ability to use the imitation of human words to ask for things they want and answer moderately complex questions. New data have demonstrated increased flexibility in the gestural communication of swarming honey bees that leads to vitally important group decisions as to which cavity a swarm should select as its new home. Although no single piece of evidence provides absolute proof of consciousness, this accumulation of strongly suggestive evidence increases significantly the likelihood that some animals experience at least simple conscious thoughts and feelings. The next challenge for cognitive ethologists is to investigate for particular animals the content of their awareness and what life is actually like, for them.
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Grubb, T. L., Foreman, J. H., Benson, G. J., Thurmon, J. C., Tranquilli, W. J., Constable, P. D., et al. (1996). Hemodynamic effects of calcium gluconate administered to conscious horses. J Vet Intern Med, 10(6), 401–404.
Abstract: Calcium gluconate was administered to conscious horses at 3 different rates (0.1, 0.2, and 0.4 mg/kg/min for 15 minutes each). Serum calcium concentrations and parameters of cardiovascular function were evaluated. All 3 calcium administration rates caused marked increases in both ionized and total calcium concentrations, cardiac index, stroke index, and cardiac contractility (dP/dtmax). Mean arterial pressure and right atrial pressure were unchanged; heart rate decreased markedly during calcium administration. Ionized calcium concentration remained between 54% and 57% of total calcium concentration throughout the study. We conclude that calcium gluconate can safely be administered to conscious horses at 0.1 to 0.4 mg/kg/min and that administration will result in improved cardiac function.
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Helton, W. S. (2005). Animal expertise, conscious or not. Anim. Cogn., 8(2), 67–74.
Abstract: Rossano (Cognition 89:207, 2003) proposes expertise as an indicator of consciousness in humans and other animals. Since there is strong evidence that the development of expertise requires deliberate practice (Ericsson in The road to excellence: the acquisition of expert performance in the arts and sciences, sports and games 1996), and deliberate practice appears to be outside of the bounds of unconscious processing, then any signs of expertise development in an animal are indicators of consciousness. Rossano's argument may lead to an unsolvable debate about animal consciousness while causing researchers to overlook the underlying reality of animal expertise. This article provides evidence indicative of animals meeting each of the three definitions of expertise established in the scientific literature: expertise as a social construction, expertise as exceptional performance, and expertise as knowledge. In addition, cases of deliberate practice by non-human animals are offered. Acknowledging some animals as experts, regardless of consciousness, is warranted by the research findings and would prove useful in solving many issues remaining in the human expertise literature.
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Hillidge, C. J., & Lees, P. (1975). Cardiac output in the conscious and anaesthetised horse. Equine Vet J, 7(1), 16–21.
Abstract: Cardiac output in the horse was measured before and at predetermined times during 2-hour periods of thiopentone-halothane and thiopentone-diethyl ether anaesthesia. Left ventricular stroke volume was decreased to a similar extent during anaesthesia with each volatile agent, but a greater reduction in cardiac output occurred during halothane anaesthesia. This finding reflected the differing effects of halothane and ether on heart rate, a slight bradycardia occurring with the former agent while ether produced a small degree of tachycardia. The latter effect was attributed to enhanced sympathoadrenal activity. Changes in cardiac output and stroke volume were considered in relation to other factors, including arterial blood pH and tensions of oxygen and carbon dioxide. Positive correlations between some of these variables and cardiac function were established. With both volatile agents the reductions in stroke volume and cardiac output were related to the duration of anaesthesia, being greatest during the early stages. Possible reasons for the tendency of stroke volume and cardiac output to return towards control levels are discussed.
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