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in Journal of the American Veterinary Medical Association

SUMMARY

Chickens (n = 18), ranging in age from 30 to 50 weeks and in body weight from 1.1 to 2.1 kg, were anesthetized with isoflurane. Ventilation was controlled, and temperature was maintained at 40.1 ± 1.0 C. The minimal anesthetic concentration (mac) of isoflurane was determined by use of a bracketing technique based on purposeful movement in response to a toe clamp. After determining isoflurane mac in triplicate, birds were given a mu-opioid agonist (morphine, n = 9) or a kappa-opioid agonist (U50488H, n = 9). Determination of mac was repeated after each IV administration of agonist in progressive doses of 0.1, 1.0, and 3.0 mg/kg of body weight. Heart rate and mean arterial blood pressure (MAP) were recorded immediately before and after each injection. Control mac (mean ± SEM) was 1.24 ± 0.05% and 1.05 ± 0.03% for the mu- and kappaopioid agonist groups, respectively. Morphine and U50488H caused a dose-dependent decrease in isoflurane mac in all birds. Reduction of mac from control (mean ± SEM) was 15.1 ± 2.7, 39.7 ± 3.1, and 52.4 ± 4.0% after the 3 successive doses of morphine and was 13.3 ± 3.0, 27.6 ± 3.3, and 40.8 ± 3.8% after U50488H was given. Each opioid injection resulted in significant (P ≤ 0.05, repeated measures anova) lowering of mac. Heart rate and MAP did not change significantly (P ≤ 0.05, paired Student’s t- test) after any dose of opioid. In conclusion, morphine or U50488H decreased isoflurane mac in dose-dependent manner without significant effect on heart rate and MAP.

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in American Journal of Veterinary Research

Summary

We investigated the influence of parasympathetic tone on the arrhythmogenicity of graded dobutamine infusions in horses anesthetized under clinical conditions. Six horses were used in 9 trials. Two consecutive series of graded dobutamine infusions were given iv; each continuous graded dobutamine infusion was administered for 20 minutes. The dobutamine infusion dosage (5, 10, 15, and 20 μg/kg of body weight/min) was increased at 5-minute intervals. Isovolumetric saline solution vehicle (v) or atropine (a; 0.04 mg/kg) was administered iv, or bilateral vagotomy (vg) was performed as a treatment before the second series of dobutamine infusions. Treatment was not administered prior to the first dobutamine infusion. Significant interaction between treatment and dosage of dobutamine infusion existed for differences from baseline for mean arterial pressure, systolic arterial pressure, diastolic arterial pressure, heart rate, and cardiac index at dosages of 5 and 10 μg of dobutamine/kg/min, given iv and for heart rate at dosage of 15 μg of dobutamine/kg/ min, given iv. Results for group-v horses were different from those for group-A and group-VG horses, but were not different between group-A and group-VG horses in all aforementioned cases, except for heart rate and cardiac index at dosage of 5 p.g of dobutamine/kg/min, given iv. Normal sinus rhythm, second-degree atrioventricular block, and bradyarrhythmias predominated during low dobutamine infusion rates during the first infusion series (nontreated horses) and in group-v horses during the second infusion series. Only tachyarrhythmias were observed during the second infusion series in the horses of the A and VG groups. The modulating influence of parasympathetic nervous system activity on hemodynamics and development of arrhythmia was conspicuous during low dobutamine infusion rates. Significant differences were not observed in hemodynamic responses to dobutamine, with respect to parasympathetic influence at high dobutamine infusion rates.

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in American Journal of Veterinary Research

SUMMARY

Dynamic baroreflex sensitivity for increasing arterial pressure (dbsi) was used to quantitatively assess the effects of anesthesia on the heart rate/arterial pressure relationship during rapid (≤ 2 minutes) pressure changes in the horse. Anesthesia was induced with iv administration of xylazine and ketamine and maintained with halothane at a constant end-tidal concentration of 1.1 to 1.2% (1.25 to 1.3 minimal alveolar concentration). Systolic arterial pressure (sap) was increased a minimum of 30 mm of Hg in response to an iv bolus injection of phenylephrine HCl. Linear regression was used to determine the slope of the r-r interval/sap relationship. During dynamic increases in sap, a significant correlation between r-r interval and sap was observed in 8 of 8 halothane-anesthetized horses. Correlation coefficients between r-r interval and sap were > 0.80 in 5 of 8 horses. Mean (± sd) dbsi was 4.8 ± 3.4 ms/mm of Hg in anesthetized horses. A significant correlation between r-r interval and sap was observed in only 3 of 6 awake horses during dynamic increases in sap. Lack of correlation between r-r interval and sap in 3 of 6 awake horses indicated that rapidly increasing sap with an iv phenylephrine bolus is a poor method to evaluate baroreceptor-mediated heart rate changes in awake horses. Reflex slowing of heart rate in response to a rising arterial pressure appeared to have been overridden by the effects of excitement. Mean (± sd) dbsi (3 horses) was 7.3 ± 3.3 ms/mm of Hg in awake horses.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of a constant-rate infusion of fentanyl on minimum alveolar concentration (MAC) of isoflurane and to determine the interaction between fentanyl and a benzodiazepine agonist (diazepam) and antagonist (flumazenil) in isoflurane-anesthetized dogs.

Animals—8 mixed-breed adult dogs.

Procedure—Dogs were anesthetized with isoflurane 3 times during a 6-week period. After a 30-minute equilibration period, each MAC determination was performed in triplicate, using standard techniques. Fentanyl was administered as a bolus (10 µg/kg of body weight, IV) that was followed by a constant infusion (0.3 µg/kg per min, IV) throughout the remainder of the experiment. After determining isoflurane-fentanyl MAC in triplicate, each dog received saline (0.9% NaCl) solution, diazepam, or flumazenil. After 30 minutes, MAC was determined again.

Results—Fentanyl significantly decreased isoflurane MAC (corrected to a barometric pressure of 760 mm Hg) from 1.80 ± 0.21 to 0.85 ± 0.14%, a reduction of 53%. Isoflurane-fentanyl-diazepam MAC (0.48 ± 0.29%) was significantly less than isoflurane-fentanylsaline MAC (0.79 ± 0.21%). Percentage reduction in isoflurane MAC was significantly greater for fentanyldiazepam (74%), compared with fentanyl-saline (54%) or fentanyl-flumazenil (61%). Mean fentanyl concentrations for the entire experiment were increased over time and were higher in the diazepam group than the saline or flumazenil groups.

Conclusion and Clinical Relevance—Fentanyl markedly decreased isoflurane MAC in dogs. Diazepam, but not flumazenil, further decreased isoflurane-fentanyl MAC. Our results indicate that diazepam enhances, whereas flumazenil does not affect, opioid-induced CNS depression and, possibly, analgesia in dogs. (Am J Vet Res 2001;62:555–560)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate effects of injection with a nonsteroidal anti-inflammatory drug (NSAID) followed by oral administration of an NSAID on the gastrointestinal tract (GIT) of healthy dogs.

Animals—6 healthy Walker Hounds.

Procedures—In a randomized, crossover design, dogs were administered 4 treatments consisting of an SC injection of an NSAID or control solution (day 0), followed by oral administration of an NSAID or inert substance for 4 days (days 1 through 4). Treatment regimens included carprofen (4 mg/kg) followed by inert substance; saline (0.9% NaCl) solution followed by deracoxib (4 mg/kg); carprofen (4 mg/kg) followed by carprofen (4 mg/kg); and carprofen (4 mg/kg) followed by deracoxib (4 mg/kg). Hematologic, serum biochemical, and fecal evaluations were conducted weekly, and clinical scores were obtained daily. Endoscopy of the GIT was performed before and on days 1, 2, and 5 for each treatment. Lesions were scored by use of a 6-point scale.

Results—No significant differences existed for clinical data, clinicopathologic data, or lesion scores in the esophagus, cardia, or duodenum. For the gastric fundus, antrum, and lesser curvature, an effect of time was observed for all treatments, with lesions worsening from before to day 2 of treatments but improving by day 5.

Conclusions and Clinical Relevance—Sequential administration of NSAIDs in this experiment did not result in clinically important gastroduodenal ulcers. A larger study to investigate the effect of sequential administration of NSAIDs for longer durations and in dogs with signs of acute and chronic pain is essential to substantiate these findings.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the degree of postoperative pain in dogs undergoing elective castration or ovariohysterectomy (OHE); determine whether an association exists between surgeon experience, incision length, or surgery duration and degree of postoperative pain; and determine whether analgesic treatment decreases expression of postoperative pain behaviors.

Design—Randomized controlled clinical trial.

Animals—426 client-owned dogs undergoing OHE or castration.

Procedures—Dogs underwent OHE or castration performed by an experienced veterinarian or a fourth-year veterinary student. Dogs were randomly assigned to 1 of 4 treatment groups: no perioperative analgesic treatment (n = 44), preoperative administration of morphine (144), preoperative administration of nalbuphine (119), and postoperative administration of ketoprofen (119). Dogs were evaluated while in the hospital before anesthesia and for 4 hours after surgery and once a day at home for 3 days after surgery.

Results—Dogs in all 4 groups had significant increases in overall pain scores after surgery, compared with baseline scores. There were significant differences among groups, with control dogs having significantly higher increases in overall pain scores than dogs in the other groups. Factors that did not influence the frequency or severity of pain-related behaviors included breed, individual hospital, anesthetic induction protocol, surgeon experience, and duration of surgery.

Conclusions and Clinical Relevance—Results suggested that dogs expressed behaviors suggestive of pain following OHE and castration, that analgesic treatment mitigated the expression of pain-related behaviors, and that surgeon experience and surgery duration did not have any effect on expression of pain-related behaviors.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To survey practicing veterinarians regarding their perceptions of and experiences with cases of suspected or confirmed animal abuse and related state laws.

DESIGN Cross-sectional study.

POPULATION Members of the Veterinary Information Network (VIN; n = 34,144) who were in veterinary practice at the time of the survey.

PROCEDURES A survey was designed and distributed online to all VIN members from January 26 to February 28, 2015. Responses were compiled, and binary logistic regression analysis was performed to identify factors that influenced decisions or perceptions regarding animal abuse encounters and related legislation.

RESULTS 1,209 completed surveys were received (3.5% response rate); 1,155 (95.5%) surveys were submitted by currently practicing veterinarians. One thousand five (87.0%) practicing veterinarians reported having encountered at least 1 case of animal abuse while in practice; 561 (55.8%) of these veterinarians indicated that they had reported at least 1 case. The most common reasons selected for reporting abuse were to protect the animal, ethical beliefs, and to protect other animals in the household. The most common reasons selected for not reporting the abuse were uncertainty that the animal had been abused, belief that client education would be better, and belief that the injury or illness was accidental versus intentional. Most respondents were unaware of the current status of laws in their state regarding animal abuse reporting.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested a need for state and national veterinary and humane-law enforcement organizations to increase communication and education efforts on recognition and reporting by veterinarians of animal abuse and the related laws.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To understand the experiences of owners of dogs with chronic pain and explore owner perceptions of their pets' pain.

DESIGN Observational study.

SAMPLE 10 owners of dogs with chronic pain.

PROCEDURES Owners were interviewed by means of a semistructured and conversational technique. Interviews were then transcribed and analyzed with standard qualitative methodology to code for major themes.

RESULTS Major themes that were identified included changes in owner schedule, effects on owner relationships, and necessary resources when owning a pet with chronic pain. Owners discussed their perceptions of their pets' pain, and several participants referred to empathizing with their pet owing to their own experiences with pain. Owners also suggested ways that veterinarians can support them during the experience of owning a dog with chronic pain.

CONCLUSIONS AND CLINICAL RELEVANCE By understanding the impact of chronic pain on dog owners and appreciating how owners perceive pain in their pets, veterinarians may be able to provide better care for patients and clients.

Full access
in Journal of the American Veterinary Medical Association