Peer-reviewed veterinary case report
How age and time of day affect tear production in dogs
By Hartley, Claudia et al.·Published in Veterinary ophthalmology·2006·The Queens Veterinary School Hospital, United Kingdom·View original on PubMed →
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Original publication title: Effect of age, gender, weight, and time of day on tear production in normal dogs.
- Species:
- dog
Plain-English summary
A study involving 100 healthy dogs found that tear production decreases as dogs get older. Specifically, for every year of age, tear production dropped by about 0.4 mm. Additionally, tear production was lower in the morning compared to the afternoon, with a difference of 0.7 mm between tests done at 10:00 am and 4:00 pm. However, these changes are minor and are not likely to affect the diagnosis of dry eye conditions in dogs.
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Abstract
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).
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/16409246/