Effects of tramadol on tear production, intraocular pressure, and pupil size in dogs: clinical study

Abstract

This study aimed to evaluate the effects of tramadol on tear production, intraocular pressure (IOP) and pupil diameter (PD) in healthy dogs. Dogs were randomly assigned to receive 4mg kg-1 (n=11) and 6mg kg-1 (n=11) of tramadol hydrochloride intramuscularly. Tear production (Schirmer tear test, STT-1), IOP (applanation tonometry) and the PD (electronic pachymetry) were assessed before, 30 and 60 minutes after administration of tramadol. Data were compared by analysis of variance for repeated measures (P<0.05). Parameters evaluated before, at 30 and 60min, in dogs treated with 4 and 6mg kg-1, were respectively: (STT-1) 22.50±3.38, 21.14±3.94 and 21.09±2.99mm min-1; and 23.05±3.73,22.64±3.76 and 22.82±3.25mm min-1. (IOP) 18.14±2.68, 17.68±2.59 and 18.23±3.84mmHg; and 19.05±2.27, 18.91±2.74 and 17.64±2.34mmHg. (PD) 6.71±0.65, 7.22±1.42 and 6.90±1.39mm; and 6.25±1.08, 6.80±1.27 and 6.49±0.90mm. All parameters evaluated did not change significantly among time points and dose regimen. Based on the conditions under which the experiments were conducted, tramadol did not affect tear production, IOP and PD in dogs, and could be used as a preoperative analgesic for intraocular surgery and pain control for any cause in patients affected by uveitis, glaucoma and keratoconjunctivitis sicca

Effects of tramadol and acepromazine on intraocular pressure and pupil diameter in young healthy cats

“…Likewise, such parameter did not change during the 60 minutes of evaluation in dogs treated with 4 and 6mm kg -1 of tramadol (RUIZ et al, 2015). CHU et al (2014) have shown that mice treated with low doses of acepromazine maintain IOP values similar to those values recorded in controls for 120 minutes.…”

“…In humans, PD changes are observed only after 120 minutes of administration of tramadol (KNAGGS et al, 2004;MATOUSKOVA et al, 2011;STOOPS et al, 2013). Lacrimal production, PD, and intraocular pressure (IOP) did not change significantly during 60 minutes of evaluation in dogs treated with different doses of tramadol (SANTOS et al, 2013;RUIZ et al, 2015). Notwithstanding, acepromazine alone or in association with hydromorphone or tramadol causes miosis in dogs (STEPHANet al, 2003, SANTOS et al, 2013.…”

“…Preoperative drugs that increase PD without affecting the IOP should be selected for intraocular surgeries (STEPHAN et al, 2003;GELATT, 2011;RUIZ et al, 2015). Nonetheless, choosing adequate protocols with these purposes may be challenging, once most of analgesic and anesthetic agents change these features (TAMURA et al, 2002;STEPHAN et al, 2003;GELATT, 2011;MAYORDOMO-FEBER et al, 2017).…”

“…; MATOUSKOVA et al, 2011;STOOPS et al, 2013); whereas in dogs treated with different doses of tramadol, PD did not change significantly during 60 minutes of evaluation (SANTOS et al, 2013;RUIZ et al, 2015). In humans, the pupillary response to tramadol is influenced by the genotype CYP2D6, which encodes isoenzymes that metabolize tramadol to its active metabolite (M1) (MATOUSKOVAet al, 2011).…”