Factors affecting tear production and intraocular pressure in anesthetized chimpanzees (Pan troglodytes)

Ellie Louise Milnes, Thalita Calvi, Yedra Feltrer, Aimee L. Drane, Glyn Howatson, Rob E. Shave, Bryony A. Curry, Joshua C. Tremblay, David Leonard Williams

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Measurements of intraocular pressure (IOP) and tear production are key components of ophthalmic examination. Chimpanzees (Pan troglodytes) were anesthetized using either tiletamine-zolazepam (TZ; 2 mg/kg) combined with medetomidine (TZM; 0.02 mg/kg), or, TZ alone (6mg/kg). Tear production was lower (P = 0.03) with TZM (5.63 ± 6.22 mm/min; n = 16) than with TZ (11.13 ± 4.63 mm/min; n = 8). Mean IOP, measured using rebound tonometry in an upright body position (n = 8) was 18.74 ± 3.01 mm Hg, with no differences between right and left eyes. However, positioning chimpanzees in left lateral recumbency (n = 27) resulted in higher IOP in the dependent (left) eye (24.77 ± 4.49 mm Hg) compared to the nondependent (right) eye (22.27 ± 4.65 mm Hg) of the same animal (P < 0.0001). These data indicate medetomidine anesthesia markedly lowers tear production in chimpanzees, and that body position should be taken into consideration when performing rebound tonometry.
Original languageEnglish
Pages (from-to)687-690
JournalJournal of Zoo and Wildlife Medicine
Issue number1
Publication statusPublished - 16 Nov 2020


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