Department of Agricultural and Environmental Sciences, State University of Santa Cruz (UESC), Ilhéus-Bahia, Brazil.
Department of Veterinary Medicine, Federal University of Western Bahia (UFOB), Barra-Bahia, Brazil.
Acta Vet Scand. 2024 Jan 17;66(1):3. doi: 10.1186/s13028-024-00724-2.
Shih-Tzu dogs are frequently affected by ocular surface disorders such as corneal ulceration and dry eye disease (DED). The aim of this study was to evaluate ocular surface homeostasis in Shih-Tzu dogs that have adequate aqueous production. Twenty-eight dogs were subjected to eyelid blink counting, Schirmer tear test (STT-1), ophthalmic evaluation, tear film break-up time (TBUT), fluorescein test and Masmali tear ferning (TF) grading scale.
Of the 28 animals evaluated, the median value of incomplete eyelid blinks/min (median = 15.0 blinks/min; Interquartil interval - IQR = 8.7 blinks/min - 19.5 blinks/min) was higher than the complete blinks/min (median = 2.5 blinks/min; IQR = 1.6 blinks/min - 4.3 blinks/min), with statistically significant difference. The Schirmer tear test had a median value of 25.0 mm/min (IQR = 22.7 mm/min - 27.5 mm/min), considered within the normal range for the species. On ophthalmic examination, all dogs had trichiasis of the caruncle and medial lower eyelid entropion. Lagophthalmos was the third most common alteration observed (71.4%; 20/28). The median of TBUT was 4.0 s; (IQR = 3.0 - 6.0 s). All the animals were negative to the fluorescein test and the TFT indicated that the majority of the eyes (51.8%; 29/56) were classified in abnormal grades 3 and 4 according to the Masmali tear ferning (TF) grading scale.
Although the Shith-Tzu dogs had STT-1 values within the normal range for the species there was high prevalence of abnormal TFT grades and low TBUT in all dogs, showing that despite adequate aqueous production, these dogs have poor precorneal tear film quality. In addition, the dogs showed few complete eyelid blinks and ophthalmic alterations, promoting poor tear film diffusion. All these findings, isolated or together, can result in DED.
西施犬常受眼部表面疾病影响，如角膜溃疡和干眼症（DED）。本研究旨在评估具有足够水液生成的西施犬的眼部表面稳态。二十八只犬接受了眨眼计数、泪液分泌试验（STT-1）、眼部评估、泪膜破裂时间（TBUT）、荧光素测试和 Masmali 泪滴蕨状图形（TF）分级评估。
在 28 只评估的动物中，不完全眨眼/分钟的中位数（中位数=15.0 次/分钟；四分位距（IQR）=8.7 次/分钟-19.5 次/分钟）高于完全眨眼/分钟（中位数=2.5 次/分钟；IQR=1.6 次/分钟-4.3 次/分钟），具有统计学显著差异。泪液分泌试验的中位数为 25.0mm/min（IQR=22.7mm/min-27.5mm/min），被认为是该物种的正常范围。在眼部检查中，所有犬的第三眼睑和内下眼睑均有倒睫和内翻。眼睑闭合不全是观察到的第三常见改变（71.4%，20/28）。TBUT 的中位数为 4.0 秒；（IQR=3.0-6.0 秒）。所有动物的荧光素测试均为阴性，TFT 表明大多数眼睛（51.8%，29/56）根据 Masmali 泪滴蕨状图形（TF）分级标准被归类为异常 3 级和 4 级。
尽管西施犬的 STT-1 值在该物种的正常范围内，但所有犬的 TFT 异常分级和 TBUT 均较高，表明尽管具有足够的水液生成，这些犬的角膜前泪膜质量仍较差。此外，这些犬的眨眼次数较少，眼部改变较少，导致泪膜扩散不良。所有这些发现，单独或联合起来，都可能导致 DED。
