Objective To evaluate the clinical relevance of intraocular pressure (IOP) measured with three different rebound tonometers in an ex vivo analysis and clinical trials in dogs. Animals and procedures Ex vivo analysis and clinical trials were performed separately. For the ex vivo analysis, eight enucleated eyes were obtained from four Beagle dogs. IOP values measured with TONOVET® (TV‐IOP), TONOVET‐Plus® (TVP‐IOP), and SW‐500® (SW‐IOP) were compared with manometric IOPs. For clinical trials, each tonometer was evaluated separately, depending on whether TVP‐IOP was higher or lower than 14 mm Hg. One‐way repeatedmeasures analysis of variance, simple linear regression analysis, and Bland‐Altman plots were used for statistical analyses. Results In ex vivo analysis, TV‐IOP and TVP‐IOP were not significantly different from manometric IOP. However, SW‐IOP underestimated IOP compared to manometry. Higher discrepancy was observed in TV‐IOP and SW‐IOP with an increase in manometric IOP. In clinical trials, no significant difference was observed between TV‐IOP (9.73 ± 2.92) and TVP‐IOP (11.36 ± 2.23) when TVP‐IOP was lower than 14 mm Hg, but SW‐IOP (8.70 ± 3.03) was significantly lower than TVP‐IOP. TV‐IOP (15.96 ± 6.47) and SW‐IOP (13.09 ± 3.72) were significantly lower than TVP‐IOP (20.08 ± 6.60) when the IOP was higher than 14 mm Hg of TVP‐IOP. Conclusions This study demonstrates that the TONOVET® and TONOVET‐Plus® provide a useful approach for ex vivo analysis. In clinical trials, results of TV‐IOP and SW‐IOP were significantly lower than of TVP‐IOP when IOP was higher than 14 mm Hg of TVP‐IOP. The characteristics of rebound tonometers should be considered in clinical settings.

Background Dry eye disease (DED) cannot be diagnosed by a single test because it is a multifactorial disorder of the ocular surface. Although studies on various dry eye tests (DETs) in dogs have been reported, standard criteria have not been established except for the Schirmer tear test 1 (STT-1). Objectives To establish reference values for DETs in dogs with normal STT-1 values (≥ 15 mm/min) and to analyze the correlation between DETs. Methods The STT-1 was performed in 10 healthy Beagle dogs (20 eyes). After 20 min, interferometry (IF) for estimating the lipid layer thickness (LLT) of the tear film, tear meniscus height (TMH), non-invasive tear breakup time (NIBUT), and meibomian gland loss rate of the upper eyelid (MGLRU) and lower eyelid (MGLRL), were measured using an ocular surface analyzer. Results Mean values for STT-1, TMH, and NIBUT were as follows: 21.7 ± 3.4 mm/min, 0.41 ± 0.21 mm, and 19.1 ± 9.5 sec, respectively. The most frequent LLT range, measured by IF, was 30–80 nm (11 eyes), followed by 80 nm (5 eyes) and 80–140 nm (4 eyes). MGLRU ≤ 25% was measured in 11 eyes and 26%–50% in 9 eyes; MGLRL ≤ 25% in 8 eyes and 26%–50% in 12 eyes. Besides positive correlation between TMH and NIBUT ( P = 0.038), there were no significant associations between DETs. Conclusions Data obtained in this study provided normative references that could be useful for diagnosing DED and for further research into correlation between DETs in dogs with DED.

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The olfactory bulb (OB) shows special characteristics in its phylogenetic cortical structure and synaptic pattern. In the OB, gamma-aminobutyric acid (GABA), as an inhibitory neurotransmitter, is secreted from GABAergic neurons which contain parvalbumin (a calcium-binding protein). Many studies on the distribution of parvalbumin-immunoreactive neurons in the rodent OB have been published but poorly reported in the avian OB. Therefore, in this study, we compared the structure of the OB and distribution of parvalbumin-immunoreactive neurons in the OB between the rat and pigeon using cresyl violet staining and immunohistochemistry for parvalbumin, respectively. Fundamentally, the pigeon OB showed layers like those of the rat OB; however, some layers were not clear like in the rat OB. Parvalbumin-immunoreactive neurons in the pigeon OB were predominantly distributed in the external plexiform layer like that in the rat OB; however, the neurons did not have long processes like those in the rat. Furthermore, parvalbumin-immunoreactive fibres were abundant in some layers; this finding was not shown in the rat OB. In brief, parvalbuminimmunoreactive neurons were found like those in the rat OB; however, parvalbumin-immunoreactive fibres were significantly abundant in the pigeon OB compared to those in the rat OB. K E Y W O R D Sexternal plexiform layer, olfactory bulb, parvalbumin, pigeon, rat | 335 LEE Et aL.

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