Objective: The aim of this study was to investigate the effect of mydriasis, and the stimulated eye, and the reproducibility of flash-stimulated visual evoked potential (fVEP) in Beagle dogs. Procedures: fVEP was recorded from both eyes of 7 healthy beagles before and after mydriasis from both eyes. fVEP recording was performed with a portable VEP system under the sedation. Plate type electrodes were used as recording, reference, and ground electrodes were placed at inion, nasion, and temporal positions, respectively. fVEP was recorded in each eye of each dog in a dimly lit room, and 128 repetitions were averaged. White flash stimulation was performed with 1.5 Hz and 3.0 cd·s/m² with an fVEP stimulator. The stimulator was set 2 cm from the subject's eye. The latencies of N2 and P2 in the fVEP component and the amplitude of between N2 and P2 (N2-P2) were measured. To evaluate the reproducibility, VEP was recorded from the same dogs again, 7 days later. Results: fVEP responses after mydriasis showed significantly shortened latencies (N2: -32%, P2: -19%) and increased amplitude (N2-P2: +60%) compared with those before mydriasis. There were no significant differences in fVEP responses between the left and right stimulated eyes. Reproducibility of the latencies of N2 and P2 was observed. Conclusion: fVEP in dogs should be recorded with mydriasis, and latency should be used to evaluate the response by our method, because of its reproducibility. Comparing the responses obtained from each eye might be useful to find a lesion site.

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A guide dog is a dog that has been trained to guide people with blindness or impaired vision. Obviously, a guide dog should have no ocular abnormality that could lead to vision loss or visual impairment such as cataract. This study aimed to determine the incidence of juvenile cataract in Labrador Retrievers that were receiving guide dog training in order to control the incidence of cataracts as well as to revise the breeding plan. A total of 213 trainee Labrador Retrievers underwent complete ophthalmic evaluations comprising menace response, pupillary light reflex, tonometry, and slit-lamp biomicroscopy. Age, gender, position of cataract in the lens, and familial relation were determined for each dog. Juvenile cataracts were detected in 17 eyes of 12 dogs. The incidence rate was 5.63%, and the mean age at detection was 1.24 ± 0.24 years. In 11 of 12 dogs, the cataracts were located in the posterior part of the lens. With respect to familial relations among the dogs with cataract, 2 dogs belonged to the same litter (group A), 2 groups (groups B and C) were from the each same father and 3 groups (groups A, D and E) were from the each same mother. In this study, the incidence rate of cataract in Labrador Retrievers was found to be higher than that in the control population reported previously. Thus, our results proved the prevalence of cataract in Labrador Retrievers. However, the incidence of cataracts in this study was slightly lower than the rate documented in previous reports in UK and The Netherlands. This underestimation of the incidence could be because we examined only juvenile Labrador Retrievers and we did not detect late-onset cataract. To confirm the incidence of cataract, our cases could be used as preliminary data for a bigger study in future. Further, in our study, most cataracts were located in the posterior part of the lens, as stated by a previous study with Labrador Retrievers. Further, we also noted a significant familial relation with respect to the incidence of cataract formation. The results of this study indicate that genetic factor is strongly related to the development of cataract, and suggest excluding all Labrador Retrievers with cataract from breeding for guide dogs. This study is still in progress, and preliminary research is needed to revise the breeding plan in order to control the incidence of cataracts in guide dogs.

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We compared the fundus photographs obtained using Clear View with those obtained using a GENESIS-Df fundus camera. Within the range of Clear View, the longitudinal and horizontal diameters were 5.13 ± 0.42 and 4.99 ± 0.45 times greater than the corresponding diameters of the optic disk. On the other hand, within the range of GENESIS-Df the longitudinal and horizontal diameters were 2.99 ± 0.33 and 3.54 ± 0.36 times greater than the corresponding diameters of the optic disk. Thus, the longitudinal and horizontal diameters differed significantly between the Clear View and GENESIS-Df images (p < 0.01, paired t -test). Moreover, the panoramic view of the fundus was created using 4.63 ± 0.32 views of Clear View, but 11.26 ± 1.93 views of GENESIS-Df. Thus, the number of sheets required to generate a panoramic view of the fundus differed significantly between the 2 cameras (p < 0.05, paired t -test). Six beginners could use both the cameras and capture clear fundus photographs. The images obtained with both the cameras were clear and of superior quality and these images could be used for diagnosis. We infer that Clear View is suitable for screening because it offers a better panoramic photograph, while GENESIS-Df is suitable for the observation of the finer details because it provide high-resolution images.

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A white and round raised focus (about 2 mm in diameter) with a few hairs was macroscopically observed in the cornea of the right eye from a male among Crl:CD(SD) rats which were purchased for a toxicity study at 5 weeks of age. During one year after the discovery, there were no changes in other corneal regions, anterior portion, optic media or fundus oculi except that the raised focus increased in roundness to form a hemispheric shape and lost it's hairs. Histopathological examination conducted at 59 weeks of age revealed normal skin structure consisting of epidermis, dermis with cutaneous appendages (hair follicles, hair roots and sebaceous glands) and subcutaneous adipose tissue. From these findings, the lesion was diagnosed as a corneal dermoid.

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[in Japanese]

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