Tear film breakup times in young healthy cats before and after anesthesia

The objectives of this study were: (i) to determine tear film breakup times (BUTs) in young healthy cats; (ii) to determine tear film BUTs in feline eyes within 8-20 h following general anesthesia; (iii) to determine if tear film BUTs vary significantly preoperatively when compared with values obtained 8-20 h postoperatively; (iv) to determine if Schirmer tear test (STT) values correlate with tear film BUTs in young healthy cats; and (v) to determine if the isolation of particular etiologic agents from conjunctival swabs of healthy cats affects tear film BUTs. We studied eighteen healthy Domestic Short-haired (n = 14) and Domestic Long-haired (n = 4) cats, with normal ocular examinations, ranging in age from 0.5 to 3 years. Complete ophthalmic examinations, including tear film BUTs, were performed on all cats. Conjunctival swabs from each eye of all cats and blood samples from all cats were collected and submitted for polymerase chain reaction screening for feline herpes virus, Chlamydophila felis, Mycoplasma spp., and calicivirus. In 10 of 18 cats, STT values and tear film BUTs were measured before general anesthesia was administered and again within 8-20 h following the end of anesthesia. Mean preanesthesia tear film BUTs for all 18 cats were 17.4 ± 4.6 s OD and 16.0 ± 4.5 s OS. Mean postanesthesia tear film BUT results were 12.5 ± 4.3 and 13.1 ± 4.0 s OD and OS, respectively. Postanesthesia tear film BUTs were significantly more rapid than those measured before anesthesia (OD only). There was also a positive correlation, both before and after anesthesia, between STT values in both eyes (OU) and tear film BUTs OU. The isolation or lack of isolation of conjunctival microorganisms using PCR did not significantly affect tear film BUTs. Mean tear film BUT in young healthy domestic cats is 16.7 ± 4.5 s. Tear BUT is positively correlated with STT values. Although mean tear film BUTs OD at 8-20 h following anesthesia were more rapid than preanesthesia values, this difference did not appear clinically relevant.