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Objective: Our aim was to generate baseline optical coherence tomography (OCT) measurements of retinal thickness in female Beagles and to determine how these are affected by meridian, eccentricity, and age. Methods: Twenty‐three female Beagles, including six puppies (<6 months old), six mature (1.8‐8.2 years old), and 11 elderly dogs (>11 years old) were studied. Both retinas of each dog were scanned (in 4 principal meridians) using the Heidelberg Spectralis following ophthalmic examination, refraction, and sedation. In each eye and each meridian, total retinal, outer retinal, and nerve fiber layer (NFL) thickness were measured from the disc rim up to 6 mm peripherally. Results: The canine retina is thickest dorsally and thinnest ventrally. Total retinal, outer retinal, and NFL thickness decrease progressively and significantly as a function of eccentricity. The greatest eccentricity‐dependent thinning occurs dorsally. This thinning is due mostly to NFL tapering, while the eccentricity‐dependent change in outer retinal thickness is more moderate, especially in the lateral meridian, possibly due to the presence of the visual streak. The retina is thickest in puppies, but there were no significant differences between mature and elderly dogs. Conclusions: Our results provide normative values for total, outer, and inner retinal thickness in female dogs and may facilitate OCT use in the diagnosis of canine glaucoma and inherited retinopathies. [ABSTRACT FROM AUTHOR]

Objective: To investigate age‐associated changes of flash visual evoked potentials (FVEPs) in sedated horses. Animal studied: Twenty‐eight clinically healthy Standardbred Warmblooded trotters, aged 36 hours to 28 years. Procedures: Light‐adapted FVEPs and FERGs were recorded (An‐vision RETIport, Roland‐consult, Germany) in response to flash stimuli. Sedation was obtained using alpha‐2‐agonists intravenously. Akinesia of the eyelids was induced and pupils were dilated. Results: Reproducible FVEPs and FERGs were readily recorded from all foals and horses. The FVEP waveform included up to four positive components (P1‐P5) and two negative components (N1 and N2) and FVEP waveform morphology was similar across all age groups. Some differences in peak times and amplitudes associated with increasing age were observed. FVEP amplitudes recorded from newborn foals were well above the amplitudes observed in normal adult horses and FVEP peak times were somewhat shorter. In adult horses, a significant increase in P4 peak time and a gradual decrease in amplitudes, mainly for N2P4, were seen across the life‐span. Conclusions: The overall equine FVEP waveform was similar across the normal life‐span of the horse in our cross‐sectional study. We found that the visual system of the foal seems to be well developed already at birth. Furthermore, our results showed a decrease in amplitudes and increase in some peak times with increasing age. We recommend that age‐matched controls should be used when evaluating foals and young horses in clinical practice, whereas horses over the age of three years can be compared to other adult horses. [ABSTRACT FROM AUTHOR]

To study retinal function in cats homozygous and heterozygous for a recessively inherited rod-cone degeneration. Dark-adapted electroretinograms (ERGs) were performed on early affected, heterozygous (ophthalmoscopically normal), and clinically normal, nonrelated cats. Responses to blue stimuli over a 3.9-log unit range were recorded. Lower b-wave amplitudes than normal were observed in heterozygotes and early affected cats. The amplitudes of the heterozygotes took an intermediate position between normal and early affected cats. Normalized amplitude/intensity data suggest a normal dynamic range in carriers. B-wave implicit times in carriers were comparable to those of normal cats. These results show that heterozygotes have an altered retinal function, although they are ophthalmoscopically normal. It is difficult to electrophysiologically differentiate heterozygotes from affected cats with the very early stage of retinal degeneration. [ABSTRACT FROM AUTHOR]

Abstract Objective The aim of the study was to evaluate if tonometry and gonioscopy could serve as predictors of later glaucoma development in the English Springer Spaniel, a breed prone to developing primary glaucoma. Animals studied Gonioscopy was performed on 279 English Springer Spaniel dogs, 119 males and 160 females, with clinically normal eyes. In addition, 14 dogs, five males and nine females were examined for glaucoma. Results A positive relation between pectinate ligament dysplasia (PLD) and narrowing of the relative width of the ciliary cleft (RWOCC) and also between PLD, RWOCC and age was demonstrated. The prevalence of PLD was 25.5%, which is higher than in other breeds reported. A positive association was demonstrated between PLD and glaucoma, as well as between narrowing of the RWOCC and glaucoma. Glaucoma was not observed in dogs with normal appearance of the iridocorneal angle. English Springer Spaniels related to dogs with glaucoma show more narrowing of the RWOCC and more PLD than unrelated dogs. Conclusion This study demonstrates the positive association between PLD and glaucoma, between narrowing of the iridocorneal angle and glaucoma and the effect of age on the iridocorneal angle. Mating of dogs with normal iridocorneal angles appears to reduce the presence and degree of abnormal appearance of the iridocorneal angle in the offspring. However, breeding only dogs with normal iridocorneal angles without consideration of their relationship to dogs with glaucoma is not a guarantee for preventing glaucoma in the offspring. [ABSTRACT FROM AUTHOR]