Systemic effects of a prolonged continuous infusion of ketamine in healthy horses.

Journal of veterinary internal medicine / American College of Veterinary Internal Medicine

PubMedID: 21781164

Elfenbein JR, Robertson SA, Corser AA, Urion RJ, Sanchez LC. Systemic effects of a prolonged continuous infusion of ketamine in healthy horses. J Vet Intern Med. 2011;25(5):1134-7.
BACKGROUND
Ketamine as continuous rate infusion (CRI) provides analgesia in hospitalized horses.

OBJECTIVE
Determine effects of prolonged CRI of ketamine on gastrointestinal transit time, fecal weight, vital parameters, gastrointestinal borborygmi, and behavior scores in healthy adult horses.

ANIMALS
Seven adult Thoroughbred or Thoroughbred cross horses, with permanently implanted gastric cannulae.

METHODS
Nonblinded trial. Random assignment to 1 of 2 crossover designed treatments. Ketamine (0.55 mg/kg IV over 15 minutes followed by 1.2 mg/kg/h) or lactated Ringer's solution (50 mL IV over 15 minutes followed by 0.15 mL/kg/h) treatments. Two hundred 3 × 5 mm plastic beads administered by nasogastric tube before drug administration. Every 2 hours vital parameters, behavior scores recorded, feces collected and weighed, and beads retrieved. Every 6 hours gastrointestinal borborygmi scores recorded. Study terminated upon retrieval of 180 beads (minimum 34 hours) or maximum 96 hours. Nontransit time data analyzed between hours 0 and 34. Results: No significant (P < .05) differences detected between treatments in vital signs or gastrointestinal borborygmi. Significant (P = .002) increase in behavior score during ketamine infusion (0.381) from hours 24-34 compared with placebo (0). Ketamine caused significant delay in passage of 25, 50, and 75% of beads (ketamine = 30.6 ± 5.3, 41.4 ± 8.4, 65.3 ± 13.5 hours versus placebo = 26.8 ± 7.9, 34.3 ± 11.1, 45.8 ± 19.4 hours), and significant (P < .05) decrease in fecal weight from hours 22 (12.6 ± 3.2 versus 14.5 ± 3.8 kg) through 34 (18.5 ± 3.9 versus 12.8 ± 6.4 kg) of infusion.

CONCLUSIONS AND CLINICAL IMPORTANCE
Ketamine CRI delayed gastrointestinal transit time in healthy horses without effect on vital parameters.