Ocular echobiometry and resistivity Index of external ophthalmic artery in agoutis (Dasyprocta prymnolopha)

Veterinary Ophthalmology provides complementary information for the diagnosis of ocular pathologies. Studies in wild species are essential. Among the diagnostic techniques in ophthalmology, two-dimensional ultrasonography stands out. The agouti is a rodent belonging to the Dasyproctidae family that has been widely used as an experimental model. For these animals, sight is one of the crucial senses for their survival. The aim of this study was to evaluate the effectiveness of the two-dimensional ocular ultrasound technique to obtain anatomical measurements and the external ophthalmic artery resistivity index, presumably normal in the species Dasyprocta prymnolopha. Forty eye bulbs of 20 adult rodents of the species were evaluated by ultrasonography. In these animals, B-mode echobiometry was performed using the transpalpebral approach and the hemodynamic study of the external ophthalmic artery using the color Doppler technique. All examinations were initiated by the left eye bulb and all measurements were performed by only one examiner. The collected data related to echobiometry were analyzed using Bioest 5.0 for Windows. Initially, normality was tested using the Shapiro-Wilk test for each parameter, then the paired t-test was performed, comparing right and left eyes, and a significance level of 5% (P < 0.05) was adopted. Based on the methodology used, the following values were obtained for the right and left eyeballs, respectively: anterior chamber thickness - mean of 1.28 ± 0.3 mm and 1.22 ± 0.1 mm; lens thickness - 8.27 ± 0.9 mm and 8.11 ± 0.9 mm; vitreous chamber thickness - 5.35 ± 0.48 mm and 5.30 ± 0.47 mm and axial length - 12.7 ± 0.9 mm and 13 ± 0.68 mm. The mean external ophthalmic artery resistivity values were 0.4305 ± 0.0390 and 0.4258 ± 0.0387 (right and left eye, respectively), characterizing a low resistance. There was no statistical difference between the right and left eyeballs in any of the studied parameters. The use of the convex transducer was feasible, promoting adequate contact with the ocular surface and images of satisfactory quality for obtaining measurements, similar to what was observed in studies evaluating the ocular biometry of primates and dogs. The anterior chamber thickness values in this experiment did not differ statistically between the antimers, as well as observed for dogs. The data obtained for lens thickness did not differ statistically for antimers, like those obtained for other rodent species evaluated with the same methodology. The mean values of vitreous chamber thickness were like those observed in chinchillas but correspond to about half of that obtained for capybaras. In this study, the external ophthalmic artery was characterized in all animals, but obtaining the spectral tracing was difficult due to its fine caliber. In wild animals, and especially in wild rodents, there are few data reporting the resistivity of the ophthalmic artery, and there is a lack of studies, which can be explained by the behavioral characteristics of defense and by the high susceptibility to stress in capture, since the performing the technique requires, as in other procedures, the use of chemical containment. (AU)

Migração cranial de diferentes volumes de iobitridol, administrados pela via epidural lombossacra, em coelhos / Cranial spread of different volumes of iobitridol, administered by epidural lumbosacral route, in rabbits

Com o objetivo de avaliar a migração cranial de diferentes volumes de iobitridol, administrado por via epidural lombossacra, bem como as possíveis alterações decorrentes dessa administração, foram utilizados 12 coelhos, sem raça definida, com 1,0±0,5 anos de idade e pesando 2,4±0,4 kg. Os animais foram anestesiados com xilazina (5 mg/kg) e cetamina (20 mg/kg), por via intramuscular, 15 minutos antes da punção lombossacra. Foram compostos dois grupos: grupo 1 (G1), onde foi administrado iobitridol, no volume de 0,33 mL/kg; e grupo 2 (G2), 0,22 mL/kg. Avaliaram-se as frequências cardíaca (FC) e respiratória (f), a duração da onda P, do intervalo PR, do complexo QRS e do intervalo QT, a saturação de oxihemoglobina (SPO2) e a temperatura retal (TR), antes da epidurografia e a cada 10 minutos após, durante 60 minutos. Também foram analisadas a migração cranial do iobitridol e a ataxia produzida. A FC, f e TR reduziram e a duração do intervalo QT aumentou após a anestesia em ambos os grupos. As durações do intervalo PR e do complexo QRS aumentaram no G1. O limite cranial da migração do meio de contraste variou entre a 4а vértebra lombar e a 8а vértebra torácica no G1 e entre a 5а vértebra lombar e a 11а vértebra torácica no G2. A ataxia foi moderada em ambos os grupos. Conclui-se que a administração do iobitridol pela via epidural lombossacra, associada à anestesia dissociativa com xilazina-cetamina, e nos volumes utilizados e sob as condições de estudo, causa alterações toleráveis nos parâmetros avaliados em coelhos hígidos, e quando utilizado neste modelo animal não causa sinais de neurotoxicidade.

In order to evaluate the cranial spread of different volumes of iobitridol, by epidural lumbosacral route, 12 mongrel rabbits, 1.0±0.5 years old, weighing 2.4±0.4 kg were used. The animals were anesthetized with xylazine (5 mg/kg) and ketamine (20 mg/kg) intramuscularly, 15 minutes before of the lumbosacral puncture. Two groups were formed: iobitridol was administered at a volume of 0.33 mL/kg in the group 1 (G1) and at 0.22 mL/kg in the group 2 (G2). The heart (HR) and respiratory rates (f), duration of P-wave, PR interval, QRS complex and QT interval, oxyhemoglobin saturation (OS) and rectal temperature (RT) were evaluated, before epidurography and every 10 minutes after, for 60 minutes. The cranial spread of iobitridol and the ataxia produced were also analyzed. FC, f and RT reduced and duration of QT interval increased after anesthesia in both groups. The duration of PR interval and QRS complex increased in G1. The cranial limit of the migration of the contrast medium varied between the 4th lumbar vertebra and the 8th thoracic vertebra in G1 and between the 5th lumbar vertebra and the 11th thoracic vertebra in G2. Ataxia was moderate in both groups. It is concluded that the administration of iobitridol by the lumbosacral epidural route, associated with dissociative anesthesia with xylazine-ketamine, and in the volumes used and under the study conditions, causes tolerable changes in the parameters evaluated in healthy rabbits, and when used in this animal model there is no signs of neurotoxicity