Cardiopulmonary effects of medetomidine in sheep and in ponies.
Abstract: Medetomidine was administered intravenously to six sheep at 5, 10 and 20 micrograms kg-1 and to one horse and four ponies at 5 and 10 micrograms kg-1. In both species medetomidine resulted in significant decreases in heart rate and cardiac output and, initially, in an increase in arterial blood pressure. In the ponies this increase in blood pressure was followed by a significant and prolonged decrease, but in the sheep the secondary decrease in blood pressure was not statistically significant. In the sheep, the three doses of medetomidine resulted in profound and significant decreases in arterial oxygen tensions, which were significantly dose related, but in the ponies the arterial blood oxygen tensions were not significantly decreased. In both species medetomidine caused a small but significant increase in arterial blood carbon dioxide tensions.
Publication Date: 1996-05-01 PubMed ID: 8735520DOI: 10.1016/s0034-5288(96)90052-1Google Scholar: Lookup
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- Journal Article
Summary
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The research studied the effects of an anesthetic drug, Medetomidine, on heart and lung functions, noting distinctions between sheep and ponies.
Methodology
- The researchers administered Medetomidine to six sheep and five equines (one horse and four ponies) intravenously.
- The dosage for sheep ranged from 5 to 20 micrograms per kilogram, while equines received 5 and 10 micrograms per kilogram.
Effects on Heart Rate and Cardiac Output
- After the administration of Medetomidine, both animal species experienced significant decreases in heart rate and cardiac output.
- Heart rate is the speed of the heartbeat measured by the number of contractions per minute, while cardiac output refers to the amount of blood the heart pumps. The decrease indicates that the drug slows the heart rate and reduces the blood circulated by the heart.
Initial Increase in Blood Pressure
- The drug initially triggered an increase in arterial blood pressure in both species.
- Arterial blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels. The temporary increase suggests that the drug initially causes the blood vessels to constrict, thus raising blood pressure.
Differential Effects on Blood Pressure
- For ponies, Medetomidine administration was marked by a significant and prolonged decline in blood pressure following the initial rise.
- Sheep, however, did not exhibit a significant secondary decrease in blood pressure. The differential effects suggest there may be species-specific reactions to the drug.
Changes in Blood Oxygen and Carbon Dioxide Levels
- In sheep, Medetomidine resulted in a substantial decrease in arterial oxygen tensions, which increased as the dosage increased.
- This change was not noticed in ponies where the arterial blood oxygen tensions didn’t decrease significantly.
- Arterial oxygen tension is the partial pressure of oxygen in arterial blood. A decrease reflects less oxygen supply in the blood.
- However, both species experienced a small but significant increase in arterial blood carbon dioxide tensions after receiving Medetomidine. This indicates the drug decreases the rate at which the body expels carbon dioxide.
Cite This Article
APA
Bryant CE, Clarke KW, Thompson J.
(1996).
Cardiopulmonary effects of medetomidine in sheep and in ponies.
Res Vet Sci, 60(3), 267-271.
https://doi.org/10.1016/s0034-5288(96)90052-1 Publication
Researcher Affiliations
- Department of Large Animal Medicine and Surgery, Royal Veterinary College, North Mymms, Hatfield.
MeSH Terms
- Animals
- Blood Pressure / drug effects
- Cardiac Output / drug effects
- Heart Rate / drug effects
- Hemodynamics / drug effects
- Horses
- Hypnotics and Sedatives / administration & dosage
- Hypnotics and Sedatives / pharmacology
- Imidazoles / administration & dosage
- Imidazoles / pharmacology
- Injections, Intravenous
- Medetomidine
- Oxygen / blood
- Partial Pressure
- Pulmonary Circulation / drug effects
- Sheep
- Time Factors
Grant Funding
- Wellcome Trust
Citations
This article has been cited 3 times.- Esmailinejad MR, Masoudifard M, Azari O, Sakhaee E, Ghalekhani N. Echocardiographic assessment of intravenous administration of medetomidine and xylazine hydrochloride at different sedative doses in one-humped camel calves (Camelus dromedarious).. Vet Res Forum 2022 Mar;13(1):39-46.
- Wiederkehr A, Barbarossa A, Ringer SK, Jörger FB, Bryner M, Bettschart-Wolfensberger R. Clinical Randomized Comparison of Medetomidine and Xylazine for Isoflurane Balanced Anesthesia in Horses.. Front Vet Sci 2021;8:603695.
- Masoudifard M, Esmailinejad MR, Sakhaee E, Azari O, Vafaei R, Ghalekhani N. Pulsed wave Doppler echocardiographic assessment after sedation by intravenous injection of medetomidine and xylazine hydrochloride on cardiac output and systolic time intervals in one-humped camel calves (Camelus dromedarious).. Iran J Vet Res 2020 Fall;21(4):257-262.
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