{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,8]],"date-time":"2026-07-08T11:37:39Z","timestamp":1783510659262,"version":"3.55.0"},"reference-count":25,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2021,10,20]],"date-time":"2021-10-20T00:00:00Z","timestamp":1634688000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>The purpose of the current study was to investigate the effects of two commonly used sedation protocols in dogs, acepromazine (ACP) and acepromazine\u2013methadone (ACP\u2013MET) combination, on tear production measured by the Schirmer Tear Test (STT) 1. We hypothesized that both sedation protocols cause a reduction in canine tear production for a variable time. Fifteen client-owned dogs were recruited for the study. Each dog was subjected to sedation twice, 2\u20133 weeks apart, and they were randomly allocated to one of two groups receiving ACP (0.015 mg kg\u22121) or ACP\u2013MET (0.010 mg kg\u22121 and 0.2 mg kg\u22121) intramuscularly. In both eyes, tear production was measured 15 min before sedation (T0) and 20 min (T20 m), 40 min (T40 m), 1 h (T1), 2 h (T2), 4 h (T4) and 8 h (T8), after drug administration. Two-way repeated measures ANOVA, followed by the Bonferroni post hoc test (p &lt; 0.05), showed a significant effect of time (p &lt; 0.0001) and treatment (p &lt; 0.0001). A significant decrease in tear production at T20 m, T40 m, T1 and T2 compared to T0 was observed in the ACP experimental protocol, while in the ACP + MET protocol, this reduction persisted until T8. Comparing the two experimental protocols, no statistically significant differences were observed at T0 or T20 m, and STT 1 values were statistically lower in the ACP + MET than the ACP protocol at the other data points. In the ACP + MET group, at T40 m, 100% of dogs showed STT 1 readings lower than 15 mm\/min. This finding is clinically relevant as it can predispose dogs to corneal injuries. The major reduction in tear production due to the ACP + MET protocol proves the need for adequate corneal hydration, particularly to discourage its use in animals with altered tear production. The data obtained provide important information helping clinicians to better manage the drug\u2019s effects on tear production.<\/jats:p>","DOI":"10.3390\/ani11113015","type":"journal-article","created":{"date-parts":[[2021,10,20]],"date-time":"2021-10-20T21:29:46Z","timestamp":1634765386000},"page":"3015","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Evaluation of Tear Production as Measured by Schirmer Test I in Dogs after Acepromazine and Acepromazine\u2013Methadone Premedication"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3049-1181","authenticated-orcid":false,"given":"Claudia","family":"Giannetto","sequence":"first","affiliation":[{"name":"Department of Veterinary Sciences, University of Messina, 98168 Messina, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4846-2581","authenticated-orcid":false,"given":"Francesco","family":"Macr\u00ec","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Messina, 98168 Messina, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Annastella","family":"Falcone","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Messina, 98168 Messina, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elisabetta","family":"Giudice","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Messina, 98168 Messina, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7629-3132","authenticated-orcid":false,"given":"Rosalia","family":"Crupi","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Messina, 98168 Messina, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luca","family":"Cicero","sequence":"additional","affiliation":[{"name":"Instituto Zooprofilattico Sperimentale della Sicilia \u201cA. Mirri\u201d, Via Gino Marinuzzi 3, 90100 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giovanni","family":"Cassata","sequence":"additional","affiliation":[{"name":"Instituto Zooprofilattico Sperimentale della Sicilia \u201cA. Mirri\u201d, Via Gino Marinuzzi 3, 90100 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2085-376X","authenticated-orcid":false,"given":"Francesco","family":"Staffieri","sequence":"additional","affiliation":[{"name":"Department of Emergency and Organ Transplantation, University of Bari, 70124 Bari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2224-0833","authenticated-orcid":false,"given":"Simona","family":"Di Pietro","sequence":"additional","affiliation":[{"name":"Department of Veterinary Sciences, University of Messina, 98168 Messina, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,10,20]]},"reference":[{"key":"ref_1","first-page":"1549","article-title":"Alterations in tear biochemistry associated with postanesthetic chronic dry eye syndrome","volume":"81","author":"Zernii","year":"2016","journal-title":"Biochemistry"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1046\/j.1463-5224.1998.00005.x","article-title":"Effects of intramuscular sedative and opioid combinations on tear production in dogs","volume":"1","author":"Dodam","year":"1998","journal-title":"Vet. Ophthalmol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"757","DOI":"10.1590\/S0034-737X2010000600009","article-title":"A comparison of the effects of propofol and thiopental on tear production in dogs","volume":"57","author":"Pontes","year":"2010","journal-title":"Rev. Ceres."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1427","DOI":"10.2460\/ajvr.72.11.1427","article-title":"Effects of acepromazine maleate or morphine on tear production before, during, and after sevoflurane anesthesia in dogs","volume":"72","author":"Mouney","year":"2011","journal-title":"Am. J. Vet. Res."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Di Pietro, S., Giannetto, C., Falcone, A., Piccione, G., Congiu, F., Staffieri, F., and Giudice, E. (2021). Dexmedetomidine and Tear Production: Evaluation in Dogs as Spontaneous Model for Ocular Surface Disorders. Vet. Sci., 8.","DOI":"10.3390\/vetsci8020028"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1111\/j.1463-5224.2009.00738.x","article-title":"Effect of acepromazine or xylazine on tear production as measured by Schirmer tear test in normal cats","volume":"13","author":"Ghaffari","year":"2010","journal-title":"Vet. Ophthalmol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"310","DOI":"10.2460\/ajvr.77.3.310","article-title":"Effects of a medetomidine-ketamine combination on Schirmer Tear Test I results of clinically normal cats","volume":"77","author":"Bonarrigo","year":"2016","journal-title":"Am. J. Vet. Res."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Di Palma, C., Micieli, F., Lamagna, B., Nieddu, A., Uccello, V., Fatone, G., and Vesce, G. (2020). Schirmer Tear Test Value and Corneal Lesions\u2019 Incidence during General Anesthesia for Non-Ophthalmic Surgery in Non-Brachycephalic Dogs: A Pilot Study Comparing Three Different Lubricant Eye Drop Formulations. Vet. Sci., 7.","DOI":"10.3390\/vetsci7010025"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1136\/vr.101231","article-title":"Evaluation of aqueous tear production in dogs after general anaesthesia with medetomidine propofol-carprofen-halothane","volume":"173","author":"Komnenou","year":"2013","journal-title":"Vet Rec."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"608","DOI":"10.2460\/ajvr.72.5.608","article-title":"Effect of duration and type of anesthetic on tear production in dogs","volume":"72","author":"Shepard","year":"2011","journal-title":"Am. J. Vet. Res."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"474","DOI":"10.1136\/vr.104040","article-title":"Effects of 390 morphine-alfaxalone-midazolam premedication, alfaxalone induction and sevoflurane maintenance on intraocular pressure and tear production in dogs","volume":"180","author":"Rubio","year":"2017","journal-title":"Vet. Rec."},{"key":"ref_12","first-page":"75","article-title":"Postanaesthetic tear production and ocular irritation in 397 cats","volume":"43","author":"Peche","year":"2015","journal-title":"Tier\u00e4rztl. Prax. Kleintiere"},{"key":"ref_13","first-page":"243","article-title":"Decreased tear production associated with general anaesthesia in the horse","volume":"182","author":"Brightman","year":"1983","journal-title":"J. Am. Vet. Med. Assoc."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"519","DOI":"10.1111\/j.1467-2995.2008.00412.x","article-title":"Effects of methadone, alone or in combination with acepromazine or xylazine, on sedation and physiologic values in dogs","volume":"35","author":"Monteiro","year":"2008","journal-title":"Vet. Anaesth. Analg."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1111\/j.1463-5224.2005.00432.x","article-title":"Effects of medetomidine and medetomidine-butorphanol combination on Schirmer tear test 1readings in dogs","volume":"9","author":"Sanchez","year":"2006","journal-title":"Vet. Ophthalmol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"564","DOI":"10.1136\/vr.155.18.564","article-title":"Effects of pethidine and fentanyl on tear production in dogs","volume":"155","author":"Biricik","year":"2004","journal-title":"Vet. Rec."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1007\/s00580-010-1135-x","article-title":"Effects of intramuscular chlorpromazine alone and chlorpromazine\u2013morphine combination on Schirmer tear test results in clinically normal dogs","volume":"20","author":"Ghaffari","year":"2011","journal-title":"Comp. Clin. Pathol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e000298","DOI":"10.1136\/vetreco-2018-000298","article-title":"Effect of methadone and acepromazine premedication on tear production in dogs","volume":"5","author":"Volk","year":"2018","journal-title":"Vet. Rec. Open"},{"key":"ref_19","unstructured":"Reinhardt, R.W. (1989). Drugs used for preanesthetic medication. Handbook of Veterinary Anesthesia, Mosby. [1st ed.]."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"636","DOI":"10.1111\/vaa.12172","article-title":"Cardiorespiratory, sedative and antinociceptive effects of dexmedetomidine alone or in combination with methadone, morphine or tramadol in dogs","volume":"41","author":"Cardoso","year":"2014","journal-title":"Vet. Anaesth. Analg."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"681","DOI":"10.2460\/javma.256.6.681","article-title":"Investigation of Schirmer tear test-1 for measurement of tear production in cats in various environmental settings and with different test durations","volume":"256","author":"Sebbag","year":"2020","journal-title":"JAVMA"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1103","DOI":"10.1007\/s10571-020-01015-w","article-title":"Regulation of opioid receptors by their endogenous opioid peptides","volume":"41","author":"Gupta","year":"2021","journal-title":"Cell Mol. Neurobiol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3234","DOI":"10.1167\/iovs.11-9051","article-title":"Spontaneous episodic decreased tear secretion in rats is related to opioidergic signaling pathways","volume":"53","author":"Zagon","year":"2012","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1111\/j.1463-5224.2005.00437.x","article-title":"Effect of age, gender, weight, and time of day on tear production in normal dogs","volume":"9","author":"Hartley","year":"2006","journal-title":"Vet. Ophthalmol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1111\/j.1463-5224.2009.00717.x","article-title":"Daytime profile of the intraocular pressure and tear production in normal dog","volume":"12","author":"Giannetto","year":"2009","journal-title":"Vet. Ophthalmol."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/11\/11\/3015\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:19:06Z","timestamp":1760167146000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/11\/11\/3015"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,10,20]]},"references-count":25,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2021,11]]}},"alternative-id":["ani11113015"],"URL":"https:\/\/doi.org\/10.3390\/ani11113015","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,10,20]]}}}