Effects of intramuscular sedative and opioid combinations on tear production in dogs

Abstract

The effect of commonly used sedation protocols on tear production rate was evaluated in dogs. Schirmer I tear tests were examined before and after intramuscular injection of acepromazine and oxymorphone (ACE + OXY; n = 7), diazepam and butorphanol (DIA + BUT; n = 8), and xylazine and butorphanol (XYL + BUT; n = 8). Two Schirmer I tear tests were also performed 15-25 min apart in dogs which received no sedative drugs (control; n = 4). Tear production rate decreased to 15 +/- 2, 17 +/- 1, and 6 +/- 1 mm min-1, respectively, while control animals averaged 21 +/- 2 mm min-1 at the same time point. Because XYL + BUT profoundly decreased tear production rate, we evaluated the two drugs separately. While BUT mildly decreased tear production when given alone to dogs (18 +/- 1 mm min-1; n = 5), xylazine had no effect on tear production. Thus it appears that the two agents act synergistically to decrease tear production rate in dogs. Moreover, sterile ocular lubricant or tear replacement should be used during XYL + BUT sedation.

Evaluation of aqueous tear production in dogs after general anaesthesia with medetomidine‐propofol‐carprofen‐halothane

“…Medetomidine and xylazine are both a 2 -adrenergic agonists. The effect of their action on tear production has been previously reported (Dodam and others 1998, Sanchez and others 2006). The combination of xylazine with butorphanol decreases the STT I values profoundly in dogs (Dodam and others 1998).…”

“…The effect of their action on tear production has been previously reported (Dodam and others 1998, Sanchez and others 2006). The combination of xylazine with butorphanol decreases the STT I values profoundly in dogs (Dodam and others 1998). However, when xylazine was administered alone in dogs, it was reported not to decrease tear production (Dodam and others 1998), although it does decrease tear production in horses (Brightman and others 1983) and in rats (Kufoy and others 1989).…”

“…The combination of xylazine with butorphanol decreases the STT I values profoundly in dogs (Dodam and others 1998). However, when xylazine was administered alone in dogs, it was reported not to decrease tear production (Dodam and others 1998), although it does decrease tear production in horses (Brightman and others 1983) and in rats (Kufoy and others 1989). In cats, the use of xylazine and acepromazine has been also reported to lead to a significant reduction in tear production soon after intramuscular drug administration (Ghaffari and others 2010).…”

Effects of intramuscular acepromazine and diazepam on tear production in rabbits

“…In a study by Dodam and others (1998), the intramuscular injection of sedatives such as acepromazine, xylazine and diazepam was found to decrease the rate of tear production in dogs. It was suggested that the reduction was caused by one or more of the following mechanisms: central effects of the drugs on the autonomic regulation of tear production, effective antinociception, vasoconstruction at the tear gland, and changes in the metabolism of the gland at the cellular level.…”

A comparison of the effects of propofol and thiopental on tear production in dogs

“…In a study comparing the effects of xylazine and butorphanol (used either in association or alone) on tear production in dogs, Dodam et al (1998) found that xylazine did not change it, while butorphanol caused a small decrease in the production of tears. However, the combination of these two drugs resulted in marked decrease in tear production, suggesting a synergistic effect for this parameter.…”