Actions of xylazine in young swine.
OBJECTIVE
To determine sedative, analgesic, and basic cardiovascular effects of xylazine administered to pigs.


METHODS
6 two-month-old Landrace x Large White pigs.


METHODS
Xylazine was administered i.v. at increasing dosages (1, 2, 4, 8, and 16 mg/kg of body weight) to otherwise unmedicated, conscious pigs, and the aforementioned effects were determined before xylazine administration and 2, 5, 10, and 15 minutes later. Then a higher xylazine dosage was given after the 15-minute measurements were taken.


RESULTS
None of the xylazine dosages induced sufficient analgesia to prevent painful response to tail clamping; considerable excitation with vocalization and without appreciable sedative effect was observed at all dosages. At lower dosages, cardiovascular effects were characterized by bradycardia and biphasic blood pressure response; initial hypertension was followed by hypotension. At higher dosages, severe hypotension with moderate bradycardia was followed by marked bradycardia and return to normal baseline values or slight increase in blood pressure.


CONCLUSIONS
Xylazine did not induce adequate sedative or analgesic effects in pigs at any dosage tested; however, cardiovascular effects were considerable. These effects of xylazine differ from those observed in other domestic species.
Gómez de Segura
I A
IA
Departamento de Cirugía, Clínica Puerta de Hierro, Universidad Autónoma de Madrid, Spain.
Tendillo
F J
FJ
Mascías
A
A
Santos
M
M
Castillo-Olivares
J L
JL
Steffey
E P
EP
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000777:Anesthetics / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001919:Bradycardia / Q000139:chemically induced / Q000503:physiopathology / Q000662:veterinary; D002320:Cardiovascular Physiological Phenomena; D002319:Cardiovascular System / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology / Q000662:veterinary; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology*; D007275:Injections, Intravenous; D013552:Swine / Q000502:physiology*; D013553:Swine Diseases / Q000139:chemically induced / Q000503:physiopathology; D013997:Time Factors; D014991:Xylazine / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*
D000700:Analgesics; D000777:Anesthetics; D006993:Hypnotics and Sedatives; D014991:Xylazine