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  • Author or Editor: Margaret-Mary McEwen x
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Objective—To evaluate cardiac function parameters in a group of active and hibernating grizzly bears.

Design—Prospective study.

Animals—6 subadult grizzly bears.

Procedure—Indirect blood pressure, a 12-lead ECG, and a routine echocardiogram were obtained in each bear during the summer active phase and during hibernation.

Results—All measurements of myocardial contractility were significantly lower in all bears during hibernation, compared with the active period. Mean rate of circumferential left ventricular shortening, percentage fractional shortening, and percentage left ventricular ejection fraction were significantly lower in bears during hibernation, compared with the active period. Certain indices of diastolic function appeared to indicate enhanced ventricular compliance during the hibernation period. Mean mitral inflow ratio and isovolumic relaxation time were greater during hibernation. Heart rate was significantly lower for hibernating bears, and mean cardiac index was lower but not significantly different from cardiac index during the active phase. Contrary to results obtained in hibernating rodent species, cardiac index was not significantly correlated with heart rate.

Conclusions and Clinical Relevance—Cardiac function parameters in hibernating bears are opposite to the chronic bradycardic effects detected in nonhibernating species, likely because of intrinsic cardiac muscle adaptations during hibernation. Understanding mechanisms and responses of the myocardium during hibernation could yield insight into mechanisms of cardiac function regulation in various disease states in nonhibernating species. (J Am Vet Med Assoc 2003;223:1170–1175)

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in Journal of the American Veterinary Medical Association


Objective—To determine hepatic effects of halothane and isoflurane anesthesia in young healthy goats.

Design—Randomized prospective clinical trial.

Animals—24 healthy 9-month-old female goats.

Procedure—Goats were sedated with xylazine hydrochloride and ketamine hydrochloride and anesthetized with halothane (n = 12) or isoflurane (12) while undergoing tendon surgery. End-tidal halothane and isoflurane concentrations were maintained at 0.9 and 1.2 times the minimal alveolar concentrations, respectively, and ventilation was controlled. Venous blood samples were collected approximately 15 minutes after xylazine was administered and 24 and 48 hours after anesthesia, and serum aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), alkaline phosphatase (ALP), and γ-glutamyltransferase (GGT) activities and bilirubin concentration were measured. Goats were euthanatized 25 or 62 days after anesthesia, and postmortem liver specimens were submitted for histologic examination.

Results—All goats recovered from anesthesia and survived until euthanasia. Serum SDH, GGT, and ALP activities and bilirubin concentration did not increase after anesthesia, but serum AST activity was significantly increased. However, serum hepatic enzyme activities were within reference limits at all times in all except 1 goat in which serum AST activity was high 24 and 48 hours after anesthesia. This goat had been anesthetized with halothane and had the longest duration of anesthesia. No clinically important abnormalities were seen on histologic examination of liver specimens.

Conclusions and Clinical Relevance—Results suggest that use of halothane or isoflurane for anesthesia in young healthy goats is unlikely to cause hepatic injury. (J Am Vet Med Assoc 2000;217:1697–1700)

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in Journal of the American Veterinary Medical Association