Peer-reviewed veterinary case report
How nasal anesthesia affects tear production in dogs
By Cochran, Shelley W et al.·Published in Veterinary ophthalmology·2026·Eye Care for Animals, United States·View original on PubMed →
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Original publication title: Beyond the Ocular Surface: Nasal Sensory Input as a Driver of Reflex Lacrimation in Dogs.
- Species:
- dog
Plain-English summary
A study found that when healthy dogs received a local anesthetic in one nostril, it affected their tear production differently based on their breed. In non-brachycephalic breeds like Australian Shepherds, the anesthetic significantly reduced tear secretion, while brachycephalic breeds like Boston Terriers showed no change. This suggests that the way dogs produce tears is linked to their nasal sensory input, which may be less effective in certain breeds. Understanding this could help veterinarians address eye problems in dogs more effectively.
People also search for: dog eye problems · why is my dog tearing up · Boston Terrier tear production · Australian Shepherd tear secretion
Abstract
OBJECTIVE: To evaluate the effect of nasal mucosal anesthesia on aqueous tear secretion in dogs and to compare responses between brachycephalic and non-brachycephalic breeds. ANIMAL STUDIED: Twenty healthy dogs (10 Australian Shepherds, 10 Boston Terriers). PROCEDURES: All dogs received 0.5 mL of 10% lidocaine or saline into one randomly selected nostril. The alternate solution was administered in the same nostril 2 weeks later. Schirmer tear test-1 (STT-1) was performed bilaterally before and 15 min after nasal administration. Tear strip wetting was recorded every 10 s for 60 s; the initial uptake phase (0-10 s) reflected uptake of pre-existing tears, while the active secretion phase (10-60 s) represented reflex tearing. Statistical comparisons included paired t-tests and linear mixed-effects models. RESULTS: In non-brachycephalic dogs, lidocaine significantly reduced STT-1 values in the treated side by 11.5% (20.0-17.7 mm, p = 0.045) and did not cause a significant change in the contralateral side (21.7-20.1 mm, -7.4%, p = 0.280). Reflex tear slope decreased by 21.7% (0.23-0.18 mm/s, p = 0.004), while the initial phase slope remained unchanged (0.84-0.88 mm/s, p = 0.653). In brachycephalic dogs, lidocaine had no significant effect in either eye or tear phase (p ≥ 0.132). Saline caused mild, non-significant increases in STT-1 across all groups (+0.4% to 8.4%, p ≥ 0.116). Mixed-effects analysis identified skull type as the only significant predictor of treatment response (p = 0.047). CONCLUSIONS: Nasal mucosal anesthesia reduced reflex tear production in dogs, particularly in non-brachycephalic breeds. These results confirm the presence of a functional nasolacrimal reflex in dogs and suggest diminished nasal sensory input in brachycephalic breeds.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/41204707/