Avaliação quantitativa da lágrima, estímulo nasolacrimal e repetitividade teste-reteste em cães braquicefálicos e não braquicefálicos

Abstract

Ocular surface disorders or aqueous tear deficiency are conditions commonly diagnosed in veterinary practice, especially in dogs. Thus, the aim of this study was to characterize diagnostic findings, test-retest repeatability, and correlations among lacrimal tests in dogs of diverse cephalic conformations. The study population comprised 50 clinically healthy dogs (25 brachycephalic and 25 non-brachycephalic). A series of diagnostics were performed in each dog, allowing for a 10min-interval between tests and repeating each test 24h 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-STT-1), and Schirmer tear test-2 (STT-2). Mean±SD test values were lower in brachycephalic vs. non-brachycephalic dogs (except for SMT; 7.4±2.0 vs. 7.3±2.4 mm/5s without significant difference), with statistically significant differences noted for CTS (1.8±0.5 cm vs. 3.4±0.8 cm), PRTT (37.2±4.0 mm/15s vs. 41.1±5.5 mm/15s), STT-1 (20.1±3.4 mm/min vs. 23.3 ±5.7 mm/min) and NL-STT1 (23.2±3.6 mm/min vs. 27.1±5.4 mm/min), and non-significant differences for EAPPTT (16.6±2.7 mm/15s vs. 17.5±2.9 mm/15s). Nasolacrimal stimulation increased STT-1 values by 18% on average. Correlations among tests were generally weak to moderate (r < 0.70) except for a strong positive correlation between STT 1 and NL-STT1 (r= 0.83, P < 0.001). Tests 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). In brachycephalic dogs was observed that corneal sensitivity and aqueous tear secretion are lower. 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.