Effects of furosemide, exercise, and atropine on tracheal mucus transport rate (TMTR) in horses were investigated. Atropine (0.02 mg/kg of body weight) administered IV or by aerosolization significantly (P < 0.05) decreased TMTR at 60, but not at 30 minutes after its administration in standing horses. Furosemide (1.0 mg/kg, IV) did not have any significant effect on TMTR when measured at 2 or 4 hours after its administration in standing horses. Exercise alone or furosemide (1.0 mg/kg, IV) administration followed 4 hours later by exercise did not alter TMTR, compared with values for standing control or exercised horses administered saline solution. Atropine (0.02 mg/kg, IV) administered after exercise significantly (P < 0.05) decreased TMTR, compared with values for no exercise standing controls, for exercise after administration of saline solution, and for furosemide and exercise.

We investigated the influence of parasympathetic tone on the arrhythmogenic dose of dobutamine in horses premedicated with xylazine, anesthetized with guaifenesin and thiamylal, and maintained on halothane in oxygen. Six horses were used in 12 randomized trials. In each trial, after end-tidal halothane concentration was stabilized at 1.1% (1.25 times minimum alveolar concentration [MAC]) in oxygen, either saline solution (0.02 ml/kg of body weight) or atropine (0.04 mg/kg) was administered IV. Five minutes later, dobutamine infusion was started at dosage of 2.5 micrograms/kg/min, IV. The dobutamine infusion was continued for 10 minutes, or until 4 or more premature ventricular complexes occurred within 15 seconds, or sustained narrow-complex tachyarrhythmia clearly not sinus in nature occurred. If the criteria for termination were not met, dobutamine infusion was increased by 2.5 micrograms/kg/min, after the hemodynamic variables had returned to baseline. The horses were allowed to recover, and were rested for at least 1 week before the second trial. The arrhythmogenic dose of dobutamine was calculated by multiplying the infusion rate by the elapsed time into infusion when arrhythmia occurred. There was significant difference between the arrhythmogenic dose of dobutamine (ADD) in saline-treated horses (mean +/- SEM, ADD 105.6 +/- 16.3 micrograms/kg) and atropinized horses (ADD 36.2 +/- 8.7 micrograms/kg). There were no differences in the prearrhythmia or immediate postarrhythmia ventricular heart rate (HR) or systolic (SAP), diastolic (DAP), or mean (MAP) arterial pressures between treated and control groups. The change in hemodynamic variables from prearrhythmia to immediate postarrhythmia formation was not different between the 2 groups. Ventricular beats were clearly evident in 8 of the 12 arrhythmias meeting the criteria for establishing the ADD. These results indicate that atropine may lower the arrhythmogenic threshold.

In vitro effects of a mixture of Escherichia coli heat-stable enterotoxins (STa and STb) on isolated jejunum of 3-week-old male pigs were studied, using everted intestinal sac techniques. Heat-stable enterotoxins increased chloride secretion and chloride absorption in everted intestinal sacs. The increase of secretory flux was greater than that for absorptive flux. Vasoactive intestinal peptide (6 x 10-9M) increased chloride secretion, but had no effect on chloride absorption. Neither vasoactive intestinal peptide nor pilocarpine (10-5M) had additive effect to ST. Secretory effects of ST were not blocked by atropine 2 x 10-5M), clonidine (10-6M), or morphine (4.2 X 10-6M).

Organophosphates (OP) and carbamates are widely utilized insecticides, but they also pose significant risks as sources ofintoxicationfor both humans and animals. A male non-descript dog, seven years old was presented with a chronic respiratory distress, dysphonia, exercise intolerance, and neurologic signs to Veterinary Clinical Complex, VCRI, Orathanadu on April 2023. Physical examination revealed elevated rectal temperature and congested mucous membrane with elevated heart beat and respiratory rate. Thoracic auscultation revealed muffled heart sound. The dog's medical history indicated a potential case of organophosphate poisoning. Treatment involved administering atropine sulfate, normal saline, ceftriaxone, and furosemide. However, throughout the treatment process, the dog continued to experience upper respiratory stridor and dyspnoea. Clinical examination and radiographic observations confirmed the diagnosis of laryngeal paralysis. This case highlights the occurrence of laryngeal paralysis polyneuropathy complex in a canine affected by organophosphate poisoning.

The purpose of the study reported here, to investigate the effect of atropine on cardio-respiratory parameters and body temperature in cats undergoing ovariohysterectomy with the combination of medetomidine-ketamine anesthesia. Twenty-six adult female intact domestic cats were admitted to Ankara University Faculty of Veterinary Medicine, Department of Obstetrics and Gynecology for routine elective ovariohysterectomy. The animals were divided into two groups by the randomized grouping method before the operation. Trial animals (n=14) received atropine together with medetomidine and ketamine anesthesia. In control animals (n=12) received the same anesthesia without atropine injection. At the end of the operation, animals were moved to the critical care unit and the measurements of vital parameters were performed. Heart, respiration rates, deep rectal temperature and status of anesthesia recovery were recorded after the operation every 10 minutes for 1 hour.There was a group, time, and group x time interaction noted for heart rate. Treatment cats showed greater heart rate during measurement. The mean respiratory rate and deep rectal temperature were in reference ranges for cats and similar for both groups. In both groups significant sedation induced, however, the scores were not statistically significant among groups.In conclusion, atropine is an effective drug preventing decrease of heart rate and patients have shown less undesirable side effects when it is used before the administration of medetomidine in cats that operated for ovariohysterectomy.

The aim of this study was to evaluate therapeutic efficacy of atropine in case ofcholinesterase (ChE) inhibitors toxicity in chicks subjected to oxidative stress (OS) withhydrogen peroxide (H2O2). H2O2 at 0.5 % in drinking water induced OS at age of 7-14days in the chicks when given each day for 14 consecutive days. There was no change inthe acute median lethal dose (LD50) for diazinon (7.9 mg/kg, orally) for both H2O(control) and H2O2 groups. The therapeutic efficacy of atropine was decreased (265 %)when measuring the median effective dose (ED50) for treating the diazinon toxicity inH2O group (2.6 mg/kg, i.m.) and in the H2O2 group (9.5 mg/kg, i.m.). The signs of acutediazinon toxicity were found to increase in H2O2 groups when compared to H2O groupand there is slight decrease in plasma and whole brain ChE activities in H2O2 group whenwhen compared to H2O group. The data revealed a decline in atropine efficacy for treatment diazinon toxicity in chicks that suffered from OS status and it is recommendedhere to increase the dose of atropine in this case.

A 12-year-old female Cocker Spaniel (7.5 kg of body weight) was presented for resection of a mammary gland tumor. During surgery, the heart rate was remarkably decreased due to a second-degree type I atrioventricular block. Atropine (0.05 mg/kg) was administered to increase the heart rate. Although the heart rate was elevated, atrial bigeminy occurred and persisted until the dog fully recovered from general anesthesia. These results highlight the possibility of atrial bigeminy caused by atropine administration during anesthesia.

Objective—To evaluate the effects of a dexmedetomidine constant rate infusion (CRI) and atropine on changes in global perfusion variables induced by hemorrhage and volume replacement (VR) in isoflurane-anesthetized dogs. Animals—8 adult dogs. Procedures—Each dog was anesthetized twice, with a 2-week interval between anesthetic sessions. Anesthesia was maintained with 1.3 times the minimum alveolar concentration of isoflurane with and without dexmedetomidine (1.6 μg/kg, IV bolus, followed by 2 μg/kg/h, CRI). Dogs were mechanically ventilated and received an atracurium neuromuscular blockade during both sessions. During anesthesia with isoflurane and dexmedetomidine, atropine was administered 30 minutes before baseline measurements were obtained. After baseline data were recorded, 30% of the total blood volume was progressively withdrawn and VR was achieved with an equal proportion of autologous blood. Results—Following hemorrhage, cardiac index, oxygen delivery index, and mixed-venous oxygen saturation were significantly decreased and the oxygen extraction ratio was significantly increased from baseline. The anaerobic threshold was not achieved during either anesthetic session. When dogs were anesthetized with isoflurane and dexmedetomidine, they had a significantly lower heart rate, cardiac index, and mixed-venous oxygen saturation during VR than they did when anesthetized with isoflurane alone. Plasma lactate concentration, mixed venous-to-arterial carbon dioxide difference, base excess, and anion gap were unaltered by hemorrhage and VR and did not differ between anesthetic sessions. Conclusions and Clinical Relevance—Results indicated that the use of a dexmedetomidine CRI combined with atropine in isoflurane-anesthetized dogs that underwent volume-controlled hemorrhage followed by VR did not compromise global perfusion sufficiently to result in anaerobic metabolism.

Objective-To quantitatively and qualitatively compare electroretinography (ERG) recordings in awake, sedated, and anesthetized dogs. Animals-Six 6-month-old Beagles. Procedures-A brief ERG protocol for dogs was used. Following 1-minute and subsequent 5-minute dark adaptation, mixed rod-cone responses were recorded bilaterally with a handheld multispecies ERG device with dogs in each of 3 states of consciousness: awake, sedated (dexmedetomidine and butorphanol), and anesthetized (atropine and hydromorphone, followed by propofol and midazolam and anesthetic maintenance with isoflurane). Low- and high-frequency noise levels were quantified via Fourier analysis, and the effect of consciousness state on signal amplitude, implicit time, and noise was analyzed via repeated-measures ANOVA. In addition, 13 veterinary ophthalmologists who were unaware of the dogs' consciousness states subjectively graded the ERG recording quality, and scores for each tracing were compared. Results-ERG amplitudes were highest in awake dogs and lowest in anesthetized dogs. Implicit times were shortest in awake dogs and longest in anesthetized dogs. Differences in b-wave amplitudes and a-wave implicit times were significant. Neither low- nor high-frequency noise levels differed significantly among consciousness states. Furthermore, no significant differences were identified among observers' scores assigned to ERG tracings. Conclusions and Clinical Relevance-Anesthesia and sedation resulted in significant attenuation and delay of ERG responses in dogs. Chemical restraint of dogs had no consistently significant effect on low- or high-frequency noise levels or on observer perception of signal quality.