Effect of age, gender, weight, and time of day on tear production in normal dogs

Claudia Hartley*, David L. Williams, Vicki J. Adams

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Objective: To investigate the effects of age, weight, gender, and of time of day on tear production in normal dogs. Animals studied: One hundred ophthalmoscopically and systemically unremarkable dogs. Procedure: Schirmer tear tests (STT) were performed every 2 h during the day on one randomly chosen eye of each of 100 dogs. Results: There was a statistically significant effect of time of day and age on the STT measurement. The mean STT decreased by 0.4 mm for every 1 year that age increased (P = 0.007). Mean STT values taken at 10:00 am were 0.7 mm lower than values taken at 4:00 pm (P = 0.04). Conclusions: Tear production decreases with age in the normal dog. In this population of dogs the largest difference was between the 10:00 am and the 4:00 pm STT measurements, but this still only amounted to 0.7 mm. This value is unlikely to be of clinical significance in the diagnosis of keratoconjunctivitis sicca (KCS).

Original languageEnglish
Pages (from-to)53-57
Number of pages5
JournalVeterinary Ophthalmology
Issue number1
Publication statusPublished - Jan 2006

Keywords / Materials (for Non-textual outputs)

  • Age
  • Dog
  • Gender
  • Keratoconjunctivitis sicca
  • Schirmer tear test
  • Time of day
  • Weight


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