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

Claudia Hartley, David L Williams, Vicki J Adams

Research output: Contribution to journalArticle (Academic Journal)peer-review

90 Citations (Scopus)


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)53-7
Number of pages5
JournalVeterinary Ophthalmology
Issue number1
Publication statusPublished - 18 Jan 2006


  • Age Factors
  • Animals
  • Body Weight/physiology
  • Circadian Rhythm
  • Dog Diseases/diagnosis
  • Dogs
  • Female
  • Keratoconjunctivitis Sicca/diagnosis
  • Male
  • Sex Factors
  • Tears/metabolism


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