Effects of high-dose gentamicin sulfate on neuromuscular blockade in halothane-anesthetized horses.
OBJECTIVE
To evaluate effects of a single high dose of gentamicin on neuromuscular function in horses anesthetized with halothane.


METHODS
6 healthy adult horses.


METHODS
Halothane-anesthetized horses were positioned in left lateral recumbency, and the right hind limb was immobilized in a reusable fiberglass cast fixed to a steel frame. The hoof was attached to a force transducer, and resting tension of 0.93 +/- 0.16 kg was maintained. A supramaximal train-of-four stimulus of 2 Hz for a duration of 0.25 millisecond was applied to the superficial peroneal nerve every 20 seconds by a square-wave stimulator. The force of the evoked digital extensor tension was recorded to determine first muscle twitch tension, compared with the baseline value (T1%) and the ratio of the force of the fourth twitch to the first twitch (T4/T1). Data were recorded at 5, 10, 15, 30, and 60 minutes after i.v. administration of vehicle or gentamicin (6 mg/kg of body weight).


RESULTS
There was a significant (P = 0.04) treatment-time interaction for the effect of gentamicin on T1%; T1% associated with vehicle decreased from 100% to 92% during the 60- minute study period, but no decrease was associated with gentamicin. For T4/T1, there was no significant effect of treatment or time or treatment-time interaction between gentamicin and vehicle.


CONCLUSIONS
Gentamicin did not cause a decrease in initial muscular strength, nor did it impair the muscles' ability to sustain strength.


CONCLUSIONS
A single high dose of gentamicin does not cause significant neuromuscular blockade when administered alone to healthy horses anesthetized with halothane.
Hague
B A
BA
Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station 77843-4474, USA.
Martinez
E A
EA
Hartsfield
S M
SM
D000704:Analysis of Variance; D000769:Anesthesia, Inhalation / Q000379:methods / Q000662:veterinary; D018685:Anesthetics, Inhalation; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000032:analysis; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage / Q000494:pharmacology*; D006221:Halothane; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006736:Horses / Q000502:physiology*; D007275:Injections, Intravenous / Q000662:veterinary; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D014677:Pharmaceutical Vehicles; D012965:Sodium Chloride; D013997:Time Factors
D018685:Anesthetics, Inhalation; D000900:Anti-Bacterial Agents; D005839:Gentamicins; D014677:Pharmaceutical Vehicles; D012965:Sodium Chloride; D002118:Calcium; D006221:Halothane