Tear film breakup time and Schirmer tear test in normal dogs: Effects of age, sex, reproductive status, skull type, and nasolacrimal duct patency

Abstract

Objective The present study aimed to determine the effects of age, sex, reproductive status, skull type, and nasolacrimal duct (NLD) patency on tear production and tear film breakup time (TBUT) in normal dogs. Animals studied The ophthalmic data of 82 healthy adult dogs were evaluated in this study. Procedures Age, sex, breed, and reproductive status were recorded. Schirmer tear test (STT) and TBUT were assessed in all dogs, and interferometry was available for the selected dogs. The Jones test was used to evaluate NLD patency. The cephalic index (CI) was calculated for each dog (skull width/skull length ×100). Results Mean (SD) values for the STT results for the right (OD) and left (OS) eyes were 20.6 (2.7) and 20.2 (2.7) mm/min, respectively. Mean (SD) TBUT values for OD and OS were 6.5 (2.5) and 6.1 (2.3) mm/min in all dogs, respectively. Sex and reproductive status had no significant effect on STT and TBUT (P[OU] > 0.05). Skull type significantly affected TBUT in both eyes (P(OD) = 0.01, P(OS) = 0.003), but had no effect on STT (P[OU] > 0.3). Age had no correlation with STT and TBUT in either eye (P[OU] > 0.05). STT and TBUT had no correlation in either eye (P[OU] > 0.2). NLD patency had no significant effect on STT or TBUT (P[OU] > 0.1). Conclusions The results of this study showed lower TBUT values in brachycephalic breeds than in non‐brachycephalic breeds. A compensatory increase in STT values was observed in dogs with low TBUT values.

An investigation into the development of qualitative tear film disorders in dogs following cryoepilation for distichiasis

“…A single study has previously evaluated TFBUT in brachycephalic breeds compared to non‐brachycephalic breeds, demonstrating a significantly more rapid TFBUT of 1.3 s in normal brachycephalic dogs compared to normal non‐brachycephalic dogs 14 . The current study found a TFBUT difference of 4.3 s between the treated group and the control group, and so, the relative increased presence of brachycephalic animals in the treatment group was unlikely to be significant enough alone to cause this vastly larger discrepancy in TFBUT values observed in the treated group.…”

The pandemic of ocular surface disease in brachycephalic dogs: The brachycephalic ocular syndrome

“…Clinicians can evaluate tear film stability using the tear film breakup time (TFBUT), a diagnostic test that provides an indirect measure of pre‐ocular mucins 77 and that correlates well with lipid layer thickness 78 . TFBUT is generally reduced in brachycephalic dogs 23,61,79,80 . A recent study of 82 healthy adult dogs showed that TFBUT was significantly lower in brachycephalic compared with non‐brachycephalic dogs 61 .…”

“…A highly cited publication from 2006 showed that tear production decreases with age in the normal dog, 60 but this information is not supported by several other studies. [61][62][63] In fact, it is possible that aqueous tear secretion remains normal with advancing age as a compensatory mechanism to developing qualitative tear film deficiency. 61…”

“…[61][62][63] In fact, it is possible that aqueous tear secretion remains normal with advancing age as a compensatory mechanism to developing qualitative tear film deficiency. 61…”

A review of diagnostic tests for qualitative and quantitative tear film deficiency in dogs

“…TFBUT is negatively correlated with age, 23 and it is shorter in brachycephalic compared to non-brachycephalic dogs. 83 Additionally, average TFBUT appears to vary greatly among canine breeds: 5.3 s (Shih Tzus), 23 8-9 s (Pugs), 13 8.45-10.77 s (variety of brachycephalic breeds), 84 13.9 s (West Highland White Terrier), 12 and 19.38-24.0 s (Beagles). 29,64,85…”