Ocular surface physiology and aqueous tear secretion in cats of diverse cephalic conformations.

Abstract

OBJECTIVE: To describe normative ocular surface and aqueous tear testing data for cats of various cephalic conformation. ANIMALS STUDIED: Fifty-three healthy adult cats (11 British Shorthair, 11 Burmese, 10 Devon Rex, 10 Scottish Fold, and 11 Sphynx). PROCEDURES: Blink rate, corneal tactile sensation (CTS), and Schirmer tear test with or without topical anesthesia (STT-1, STT-2) and with nasolacrimal stimulation (NL-STT1, NL-STT2) were assessed. Palpebral fissure length (PFL) and skull morphology were measured, and cephalic index (CI) and craniofacial ratio (CFR) calculated. RESULTS: Mean&#x2009;&#xb1;&#x2009;SD test results were as follows: blink rate (5.0&#xa0;&#xb1;&#x2009;2.3 blinks/min), CTS (3.2&#xa0;&#xb1;&#x2009;0.7&#xa0;cm), STT-1 (11.2&#xa0;&#xb1;&#x2009;4.3&#x2009;mm/min), STT-2 (6.7&#xa0;&#xb1;&#x2009;3.6&#x2009;mm/min), NL-STT1 (13.4&#xa0;&#xb1;&#x2009;5.7&#x2009;mm/min), NL-STT2 (13.5&#xa0;&#xb1;&#x2009;5.2&#x2009;mm/min), and PFL (2.0&#xa0;&#xb1;&#x2009;0.2&#xa0;cm). Corneal sensitivity did not differ significantly among breeds (p&#xa0;=&#x2009;.152) but was negatively correlated with body weight (r&#xa0;=&#x2009;-.32, p&#xa0;=&#x2009;.019). STT-1 significantly differed among breeds (p&#xa0;<&#x2009;.001) and was lowest in Sphynx cats (8.7&#xa0;&#xb1;&#x2009;4.3&#x2009;mm/min). A positive correlation was detected between STT-1 values at 30 and 60&#x2009;s (r&#xa0;=&#x2009;.98; p&#xa0;<&#x2009;.001). The nasolacrimal reflex significantly increased STT in anesthetized and unanesthetized eyes (approximately +100% and&#x2009;+20%, respectively; p&#xa0;&#x2264;&#x2009;.002). STT-1 tended to be higher in intact versus neutered cats (p&#xa0;=&#x2009;.062). Age did not impact any test result (p&#xa0;&#x2265;&#x2009;.085). CONCLUSIONS: Normative data described here serve as a baseline for future studies assessing ocular surface disease in multiple feline breeds. Unlike dogs, brachycephalic cats did not have lower CTS or STT-1 than non-brachycephalic cats.