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Effect of methadone and acepromazine premedication on tear production in dogs

Research output: Contribution to journalArticle

  • Hayley Volk
  • Eleanor West
  • Rose N Linn-Pearl
  • Georgina V Fricker
  • Ambra Panti
  • David Gould

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    Rights statement: © British Veterinary Association 2018. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.

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    Licence: Creative Commons: Attribution Non-Commercial (CC-BY-NC)

Original languageEnglish
JournalVeterinary Record
Early online date5 Dec 2018
Publication statusE-pub ahead of print - 5 Dec 2018


Objectives To evaluate the combined effect of intramuscular acepromazine and methadone on tear production in dogs undergoing general anaesthesia for elective, non-ocular procedures. Design Prospective, non-randomised, pre-post treatment study. Setting Patients were recruited from a referral practice in the United Kingdom. Methods Thirty client-owned dogs were enrolled in this study and received a combined intramuscular premedication of methadone (0.3 mg/kg) and acepromazine (0.02 mg/kg) prior to general anaesthesia for elective, non-ocular procedures. Full ophthalmic examination was performed and tear production was quantified using the Schirmer tear test-1 (STT-1). On the day of general anaesthesia, an STT-1 was performed before (STT-1a) and after (STT-1b) intramuscular premedication with methadone/acepromazine. Results Using a general linear model, a significant effect on STT-1 results was found for premedication with methadone/acepromazine (P = 0.013), but not eye laterality (P = 0.527). Following premedication, there was a significant reduction observed in the mean STT-1 readings of left and right eyes between STT-1a (20.4 ± 2.8 mm/min) and STT-1b (16.9 ± 4.1 mm/min; P < 0.001). Significantly more dogs had an STT-1 reading less than 15 mm/min in one or both eyes after premedication (30%; 9/30 dogs) compared with before premedication (6.7%; 2/30 dogs; P = 0.042). Conclusions An intramuscular premedication of methadone and acepromazine results in a decrease in tear production in dogs prior to elective general anaesthesia. This may contribute to the risk of ocular morbidities, such as corneal ulceration, particularly in patients with lower baseline tear production.

    Research areas

  • acepromazine, canine, methadone, premedication, Schirmer tear tes

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