Parenteral Anticholinergics in Dogs With Normal and Elevated Intraocular Pressure

Abstract

Dogs given parenteral anticholinergic drugs have been thought to be at risk for development or exacerbation of elevated intraocular pressure (IOP). In a randomized, blinded, placebo-controlled study, we evaluated the effect of intramuscular glycopyrrolate (0.01 mg/kg) on pupil diameter and IOP in unanesthetized normal dogs. Treatment with glycopyrrolate did not change pupil diameter or IOP from baseline, nor were there differences between glycopyrrolate and saline-treated (control) dogs. In addition, the authors retrospectively reviewed the medical records of 2,828 dogs undergoing general anesthesia between April 1987 and September 1990 to determine if there was an association between parenteral anticholinergic medication and postanesthetic elevation in IOP. The authors also determined the frequency of bradycardia requiring anticholinergic therapy during anesthesia in dogs with glaucoma. Of the 2,828 cases reviewed, the records of 46 dogs coded for glaucoma were examined in detail. The 46 dogs underwent 62 episodes of anesthesia, with 23 episodes including exposure to an anticholinergic drug. An increase in IOP from preanesthetic to postanesthetic measurement occurred in three dogs. One of these dogs received anticholinergic medication for bradycardia during anesthesia. The postanesthetic elevation in IOP in this dog was probably not drug related. Preanesthetic anticholinergic administration did not affect the incidence of anticholinergic administration for bradycardia during the anesthetic episode. Anticholinergic therapy during anesthesia was more frequent when the preanesthetic medication included an opiate drug. These studies do not indicate an association between parenteral anticholinergic administration and elevations in IOP.

Ocular side‐effects of tolterodine and oxybutynin, a single‐blind prospective randomized trial

“…Some research has demonstrated that anticholinergic medication does not alter PD in dogs [10], whereas other work has shown that these agents cause mydriasis in men [11]. In our study, we evaluated PD under the bright and dim light of the slit‐lamp.…”

“…In one canine study, animals that were placed under general anaesthesia and received anticholinergic medication showed no significant rise in IOP, and the IOP values were similar to those in a group of dogs who received intravenous saline [10]. However, findings in humans with closed‐angle glaucoma indicate that anticholinergics may increase IOP [11, 12].…”

Changes in intraocular pressure and pupil size following intramuscular administration of hydromorphone hydrochloride and acepromazine in clinically normal dogs

“…It is recognized that parental administration of preanesthetic and anesthetic agents will normally cause decreases in IOP, with the exception of ketamine which results in increased IOP. 18,19 Pupil size is similarly affected as most preanesthetic, anesthetic or sedative agents cause miosis, with the exception of ketamine which causes mydriasis. 20 The purpose of this study was to investigate how a commonly used opioid analgesic would effect conditions of PS and IOP.…”

481Ocular side effects of tolterodine and oxybutynin: A single-blind prospective randomized trial

“…In one canine study, animals that were placed under general anaesthesia and received anticholinergic medication showed no significant rise in IOP, and the IOP values were similar to those in a group of dogs who received intravenous saline [10]. However, findings in humans with closed-angle glaucoma indicate that anticholinergics may increase IOP [11,12].…”