Cardiovascular effects of N-butylscopolammonium bromide and xylazine in horses

Comparative study of the bronchodilator efficacy and adverse effects of salbutamol and hyoscine butylbromide in horses with severe asthma

BACKGROUND

Salbutamol and hyoscine butylbromide (HBB) are commonly used bronchodilators in horses with severe asthma (SA).

OBJECTIVE

To compare the bronchodilation potency, duration, and adverse effects of salbutamol and HBB in SA.

ANIMALS

Six horses in exacerbation of SA.

METHODS

The effects of inhaled salbutamol (1000 μg) and HBB (150 mg, IV) were compared in a randomized, blinded, crossover experiment. Lung function, intestinal borborygmi and heart rate were assessed before and sequentially until 180 minutes after drug administration, and analyzed with 2-way repeated-measures ANOVA and Dunnett's multiple comparison tests.

RESULTS

Both treatments caused a similar improvement in lung function. Pulmonary resistance and reactance returned to baseline values within 30 minutes after HBB administration, whereas salbutamol improved reactance until 180 minutes (mean improvement at 180 minutes of 0.040 Kpa/L/s, 95% CI = 0.004 to 0.076; P = .02 for salbutamol and of 0.009 Kpa/L/s, 95% CI = -0.028 to 0.045; P = .98 for HBB for the resistance at 3 Hz and of 0.040 Kpa/L/s, 95% CI = 0.007 to 0.074; P = .01 for salbutamol and of 0.009 Kpa/L/s, 95% CI = -0.024 to 0.042; P = .97 for HBB for the reactance at 7 Hz). From 5 to 30 minutes after HBB administration, the heart rate accelerated (mean increase of 3.3 beats per minute, 95% CI = -6.6 to 13.1; P = .92 for salbutamol, and of 13.0 beats per minute, 95% CI = 3.6 to 22.4; P = .002 for HBB at 30 minutes) and the gut sounds decreased (mean reduction of 1.3, 95% CI = -0.1 to 2.8; P = .09 for salbutamol and of 2.8 for the gastrointestinal auscultation score, 95% CI = 1.4 to 4.3; P < .0001 for HBB at 30 minutes).

CONCLUSIONS AND CLINICAL IMPORTANCE

Both drugs have a similar bronchodilator potency but with a longer duration for salbutamol. Gastrointestinal and cardiovascular effects were noted only with HBB, suggesting the preferential use of salbutamol to relieve bronchoconstriction in horses with asthma.

Ultrasonographic Assessment of Small Intestinal Motility Following Hyoscine Butylbromide Administration in Horses: A Pilot Study

Horses commonly receive hyoscine butylbromide (HB) prior to hospital admission for colic. This could alter the appearance of the small intestine (SI) on ultrasound scan and affect clinical decision making. The aim of this study was to assess the impact of HB on ultrasonographically assessed SI motility and heart rate. Six horses hospitalised for medical colic with no significant abnormalities on baseline abdominal ultrasound examination were included. Ultrasound was performed in three locations (right inguinal, left inguinal and hepatoduodenal window) before and at 1, 5, 15, 30, 45, 60, 90, and 120 minutes after intravenous injection of 0.3 mg/kg HB. Three blinded reviewers assessed SI motility using a subjective grading scale from 1 to 4, one being normal motility and four being no motility. Moderate interindividual and interobserver variability was observed, but none of the included horses developed dilated turgid loops of SI. Hyoscine butylbromide did not significantly reduce SI motility grade in any location (P = .60 left inguinal, P = .16 right inguinal, P = .09 duodenum). Heart rate (mean ± SD) was 33 ± 3 prior to HB injection and peaked at 71.3 ± 9 one-minute postinjection. Heart rate was significantly increased until 45 minutes (48 ± 9) after HB administration (P = .04). The appearance of dilated turgid SI loops common with strangulating intestinal lesions did not appear to develop following HB administration. Hyoscine butylbromide administered shortly before abdominal ultrasound examination would not be expected to affect clinical decision making in horses without small intestinal disease.

Critical Care of the Colic Patient: Monitoring, Fluid Therapy, and More

A successful outcome to management of the critical colic patient is highly dependent on how the patient is monitored and treated, particularly, in the perioperative period. In this article, we will provide an update on monitoring techniques, advances in fluid therapy, nutrition management and pharmacotherapeutic agents, inclusive of pain monitoring and management, prokinetics, and management of systemic inflammatory response syndrome and the hypercoagulable state.

Evaluation of the colic in horses: decision for referral

This article presents an overview of key factors that should alert the practitioner toward referral of a colic patient to a facility capable of surgical exploration or intensive medical management. Discussion includes a review of important aspects of colic history, signalment, physical examination findings, and diagnostic test results that indicate that a more serious medical or surgical condition exists, and advanced therapy is necessary.

Hyoscine-N-butylbromide premedication on cardiovascular variables of horses sedated with medetomidine

OBJECTIVE

To evaluate the effects of intravenous (IV) or intramuscular (IM) hyoscine premedication on physiologic variables following IV administration of medetomidine in horses.

STUDY DESIGN

Randomized, crossover experimental study.

ANIMALS

Eight healthy crossbred horses weighing 330 ± 39 kg and aged 7 ± 4 years.

METHODS

Baseline measurements of heart rate (HR), cardiac index (CI), respiratory rate, systemic vascular resistance (SVR), percentage of patients with second degree atrioventricular (2(o) AV) block, mean arterial pressure (MAP), pH, and arterial partial pressures of carbon dioxide (PaCO2 ) and oxygen (PaO2 ) were obtained 5 minutes before administration of IV hyoscine (0.14 mg kg(-1) ; group HIV), IM hyoscine (0.3 mg kg(-1) ; group HIM), or an equal volume of physiologic saline IV (group C). Five minutes later, medetomidine (7.5 μg kg(-1) ) was administered IV and measurements were recorded at various time points for 130 minutes.

RESULTS

Medetomidine induced bradycardia, 2(o) AV blocks and increased SVR immediately after administration, without significant changes in CI or MAP in C. Hyoscine administration induced tachycardia and hypertension, and decreased the percentage of 2(o) AV blocks induced by medetomidine. Peak HR and MAP were higher in HIV than HIM at 88 ± 18 beats minute(-1) and 241 ± 37 mmHg versus 65 ± 16 beats minute(-1) and 192 ± 38 mmHg, respectively. CI was increased significantly in HIV (p ≤ 0.05). Respiratory rate decreased significantly in all groups during the recording period. pH, PaCO2 and PaO2 were not significantly changed by administration of medetomidine with or without hyoscine.

CONCLUSION AND CLINICAL RELEVANCE

Hyoscine administered IV or IM before medetomidine in horses resulted in tachycardia and hypertension under the conditions of this study. The significance of these changes, and responses to other dose rates, requires further investigation.