Ophthalmic Patients

Effect of sedation with butorphanol on variables pertaining to the ophthalmic examination in dogs

“…The pupillary effects of exogenous opioids are species dependent and are believed to be mediated predominantly through central mechanisms, although some data suggest a possible effect on iris opioid receptors . Administration of opioids by various routes induces miosis in humans, dogs, and rabbits, while mydriasis is observed in monkeys, cats, and mice . In all dogs of the current study, a significant pupillary constriction was observed at every time point following drug administration (T 10 to T 45 ), compared to baseline.…”

“…37 Administration of opioids by various routes induces miosis in humans, dogs, and rabbits, while mydriasis is observed in monkeys, cats, and mice. [38][39][40] In all dogs of the current study, a significant pupillary constriction was observed at every time point following drug administration (T 10 to T 45 ), compared to baseline. The reduction in pupil diameter observed in the butorphanol-treated dogs was anticipated given that it has been previously reported after intravenous administration of 0.4 mg/kg.…”

“…43 With the exception of ketamine, which induces mydriasis in dogs, 44 most commonly used sedative agents are assumed to cause miosis in domestic animals. 5,40 This has been recently documented in dogs with medetomidine, 45 dexmedetomidine, 46 and diazepam. 44 As mydriasis is necessary for lens and fundus examination, it would be relevant to know whether sedation of ophthalmic canine patients with butorphanol may prevent or delay pupillary dilation, a side effect reported with morphine in dogs.…”

“…The kappa opioid receptors have been hypothetized to be involved in the process of pupil constriction, and their site of action could be, in part, the central nervous system . With the exception of ketamine, which induces mydriasis in dogs, most commonly used sedative agents are assumed to cause miosis in domestic animals . This has been recently documented in dogs with medetomidine, dexmedetomidine, and diazepam .…”

Comparison of intraocular pressure, tear production and cardiorespiratory variables before and after induction of anaesthesia with either propofol or ketofol in dogs premedicated with midazolam

“…An adequate and efficient tear film should cover the cornea in order to provide lubrication between the lids and ocular surface, to protect the eye against microbial protein sources and to facilitate drainage of debris and exfoliated cells (Gross and Pablo 2015). Generally, tear production decreases during general anaesthesia; however, STT-1 showed no statistically significant changes following administration of propofol, but not alfaxalone, in dogs (Costa et al 2014).…”