Aqueous tear assessment in dogs: Impact of cephalic conformation, inter‐test correlations, and test‐retest repeatability

Bolzani, Hellen
Sebbag, Lionel
Oriá, Arianne
Raposo, Ana Claudia
Sebbag, Lionel
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Veterinary Clinical Sciences
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Biomedical SciencesVeterinary Clinical Sciences

Objective - To characterize diagnostic findings, test‐retest repeatability, and correlations among lacrimal tests in dogs of diverse cephalic conformations.

Animal studied - Fifty healthy dogs (25 brachycephalic, 25 nonbrachycephalic).

Procedures - A series of diagnostics were performed in each dog, allowing for a 10‐minute interval between tests and repeating each test 24 hours later under similar conditions: corneal tactile sensation (CTS), strip meniscometry test (SMT), phenol red thread test (PRTT), endodontic absorbent paper point tear test (EAPPTT), Schirmer tear test‐1 without (STT‐1) or with nasolacrimal stimulation (NL‐STT1), and Schirmer tear test‐2 (STT‐2).

Results - Mean ± SD test values were lower in brachycephalic vs. nonbrachycephalic dogs (except for SMT; 7.4 ± 2.0 mm/5 seconds vs 7.3 ± 2.4 mm/5 seconds), with statistically significant differences noted for CTS (1.8 ± 0.5 cm vs 3.4 ± 0.8 cm), PRTT (37.2 ± 4.0 mm/15 seconds vs 41.1 ± 5.5 mm/15 seconds), STT‐1 (20.1 ± 3.4 mm/min vs 23.3 ± 5.7 mm/min), STT‐2 (13.0 ± 3.4 mm/min vs 16.9 ± 3.9 mm/min), and NL‐STT1 (23.2 ± 3.6 mm/min vs 27.1 ± 5.4 mm/min), and nonsignificant differences for EAPPTT (16.6 ± 2.7 mm/15 seconds vs 17.5 ± 2.9 mm/15 seconds). Nasolacrimal stimulation increased STT‐1 values by 18% on average. Correlations among tests were generally weak to moderate (r < .70) except for a strong correlation between STT‐1 and NL‐STT1 (r = .83, P < .001). Test reliability was good although test‐retest repeatability was generally poor to moderate, as depicted by low intraclass correlation coefficients (ICC ≤ 0.75) and wide 95% limits of agreement, except for CTS (ICC = 0.91).

Conclusions - Corneal sensitivity and aqueous tear secretion are lower in brachycephalic dogs. A comprehensive assessment of the ocular surface requires the combination of several diagnostic tests. The nasolacrimal reflex may provide a useful diagnostic and therapeutic tool in dogs.


This is the peer-reviewed version of the following article: Bolzanni, Hellen, Arianne P. Oriá, Ana Claudia S. Raposo, and Lionel Sebbag. "Aqueous tear assessment in dogs: Impact of cephalic conformation, inter‐test correlations, and test‐retest repeatability." Veterinary Ophthalmology (2020), which has been published in final form at DOI: 10.1111/vop.12751. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Posted with permission.