Peer-reviewed veterinary case report
Methadone effects on eye pressure, pupil, and tears in healthy dogs
By Raušer, Petr et al.·Published in Topics in companion animal medicine·2022·Department of Surgery and Orthopedics·View original on PubMed →
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Original publication title: Influence of Methadone on Intraocular Pressure, Pupil Size, and Aqueous Tear Production in Healthy Dogs.
- Species:
- dog
Plain-English summary
A group of healthy dogs received either intravenous or intramuscular methadone to see how it affected their eye pressure, pupil size, and tear production. The study found that while tear production decreased slightly after 30 minutes in the dogs given intravenous methadone, it stayed within normal limits. There were no significant changes in eye pressure or pupil size, and the heart rate dropped in the intravenous group. Overall, methadone at this dose did not cause any major issues with eye health in these dogs.
People also search for: dog eye pressure treatment · methadone effects on dog eyes · dog tear production decrease · healthy dog pupil size changes
Abstract
Intraocular pressure (IOP), pupil size (PS), and tear production are variables important in maintaining eye homeostasis. The purpose of this study was to determine the effects of methadone on IOP, PS, and tear production measured by Schirmer I tear test (STT-I) in healthy nonpainful dogs. A prospective, randomized, "double-blind" clinical study was performed. A total of 40 healthy conscious client-owned dogs were included in the study. Dogs were allocated randomly to 1 of 3 groups and given intravenous methadone 0.3 mg/kg (Met-IV, n = 15), intramuscular methadone 0.3 mg/kg (Met-IM, n = 15), or saline 0.3 mL/kg (SAL, n = 10). IOP, PS, STT-I, heart rate (HR), and mean arterial pressure (MAP) were measured prior to (baseline) and at 2, 5, 10, 20, and 30 minutes after drug administration. Data were analyzed using 1-way and 2-way repeated measures ANOVA or their nonparametric equivalents (P < .05). No significant differences in IOP and PS within or between the groups were detected. In the Met-IV group, the STT-I decreased significantly after 30 minutes (P = .025), however, the values remained within the physiological ranges. In Met-IV group, HR decreased significantly at 5, 10, 20, and 30 minutes, respectively. No other significant differences were observed. Methadone administered at a dose of 0.3 mg/kg intravenously or intramuscularly seems to cause within 30 minutes no clinically important effect on IOP, PS, and STT-I in healthy conscious nonpainful dogs without ocular abnormalities.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/36272536/