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Abstract

Objective—To determine baseline tear pH in dogs, horses, and cattle by use of a microelectrode.

Animals—28 dogs, 24 horses, and 29 cattle.

Procedures—Under manual restraint, tears were collected from each subject's left eye with cotton spears. A Schirmer tear test was performed in the right eye. Tears were extracted from the spears by centrifugation. Tear volume was measured, pH was determined with a microelectrode, and total solids (TS) concentration was measured by refractometry.

Results—Mean ± SD pH of tears in cattle, dogs, and horses was 8.32 ± 0.14, 8.05 ± 0.26, and 7.84 ± 0.30, respectively. Tear pH was significantly higher in cattle versus dogs and horses and in dogs versus horses. Mean ± SD TS concentration in horses, cattle, and dogs was 2.04 ± 1.29 g/dL, 1.07 ± 0.60 g/dL, and 0.33 ± 0.18 g/dL, respectively. Total solids concentration was significantly higher in horses versus cattle and dogs and in cattle versus dogs. Schirmer tear test results for all animals were within the species reference range.

Conclusions and Clinical Relevance—Tear pH in all 3 species differed from that of published blood pH values and the pH of common topically administered ophthalmic medications. These fndings may have implications for variations in ocular flora and defense mechanisms, susceptibility to ocular disease, and success or comfort of topical treatment.

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in American Journal of Veterinary Research

[observer 2]) during 4 testing periods over 2 days in a prospective, randomized study to determine intra- and interobserver reliability of the TFBUT test as it would be performed in a clinical environment with and without administration of a topical

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in American Journal of Veterinary Research

between these studies include investigator variability in application of the aesthesiometer filament to the cornea; differences in investigator interpretation of the blink response; and variation in the testing environment between the 2 studies, as

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in American Journal of Veterinary Research

power of the anterior and posterior cornea and lens. 45 The refractive state can also be temporarily or permanently modified by adaptations to the globe or changes to the environment. In the present study, many cats were housed in an animal shelter in

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in American Journal of Veterinary Research

environment and at a similar time of day, time of year, and ambient temperature to minimize effects of those variables on tear production. Tear production was recorded as millimeters of wetting per minute. CTT —The CTT was measured with a Cochet

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in American Journal of Veterinary Research

published studies regarding blinking physiology of horses. The purpose of the study reported here was to determine values for SEBR and characterize blink patterns of horses in a controlled environment. We intended to use high-speed videography and image

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in American Journal of Veterinary Research

same restraint and in a similar stall environment for each subject. Results suggested that topical corneal anesthesia with 0.5% proparacaine hydrochloride may not provide adequate anesthesia in horses. Because of the length of time required to perform

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in American Journal of Veterinary Research

, such as dogs and cats. One theory to explain this discrepancy is that small rodents, such as chinchillas, guinea pigs, and BTPDs, inhabit desert or dry grassland environments; hence, low aqueous tear production may be a fluid conservation mechanism

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in American Journal of Veterinary Research

indirect ophthalmoscopy, and rebound tonometry. They were kept in a familiar environment and acclimated to IOP and VPD measurement procedures by taking measurements at 6-hour intervals for 48 hours prior to data collection. Food was withheld for 12 hours

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in American Journal of Veterinary Research

eyes of those horses was evident after discontinuation of interventions. 28 This illustrates that multiple host and environment factors influence microbial populations. In addition to topical application of an antimicrobial, there were multiple

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in American Journal of Veterinary Research