Ocular Echobiometry and Resistivity Index of External Ophthalmic Artery in Agoutis (Dasyprocta prymnolopha)

Background: 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.Materials, Methods & Results: 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.Discussion: 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.Keywords: Doppler flow, ultrasound, eye, agouti

Presumed Normal Hemodynamic Values of the Arteries in the Final Third Period of Gestation in Bitches

Background: Doppler ultrasonography enables the investigation of vascular blood flow indexes in gestational assessment, being able to detect vascular resistances that can affect fetal and maternal circulation, such as cases of placental insufficiency, associated with fetal cerebral oxygenation deficit and fetal distress. The study aims to assume hemodynamically normal values in the final third of gestation in bitches, of the umbilical, uteroplacental, middle cerebral and internal carotid arteries, correlating the obtained Doppler velocimetric indexes, for the assessment of the feto-placental circulation, and prediction of fetal viability indexes, fetal centralization and probable date of delivery.Materials, Methods & Results: Thirty healthy bitches were examined in the final third of gestation (40-60 days). These were evaluated by Doppler ultrasonography at 2 times (T): T1: between 40-50 days; T2: between 51-60 of gestation. At each time point, the peak systolic velocities (PSV) and end-diastolic velocities (EDV) used to obtain the pulsatility (IP) and resistivity (IR) indexes of the umbilical, uteroplacental, middle cerebral and internal carotid arteries of fetuses were evaluated. Also, the systole/diastole (S/D) ratio of these vessels was evaluated. The data obtained were subjected to analysis of variance and Tukey test, using a P value equal to 5%. A significant difference was observed between velocities and Doppler velocimetric indexes between the 2 phases of the gestational final third in all studied vessels. There was an increase in the values of PSV and EDV and a decrease in the indexes, as the probable date of delivery approached. The analysis of the umbilical cord IR showed an increase from P1 to P2 (P < 0.05), while the IP decreased at the same time. For all studied variables there was a statistically significant difference (P < 0.05). In the uteroplacental artery, similarly to the umbilical artery, the PSV and EDV values showed an increase between P1 and P2, while the S/D ratio decreased up to 60 days of gestation (P2). The IR and IP of these vessels decreased during the study interval in pregnant bitches. The studied variables showed a statistically significant difference when analyzed comparatively between P1 and P2 (P < 0.05). As for the middle cerebral artery and internal carotid artery, the PSV and EDV values increased until the end of pregnancy. Likewise, the Doppler velocimetric values and the S/D ratio decreased until the end of pregnancy (P2).Discussion: The hemodynamic values obtained for the umbilical artery and uterine artery were significantly different between 40 and 50 days of gestation (P1) and 50 and 60 days of gestation (P2), with a decrease in vascular resistance and an increase in velocities. It can be related to a greater association of maternal-fetal blood perfusion, due to the increased demand for the development of the fetus. The Middle Cerebral Artery (MCA) also showed changes between P1 and P2, with an increase in PSV and EDV in the final third of pregnancy, and the S/D ratio was reduced, differing significantly between P1 and P2. The systolic (PSV) and diastolic (EDV) flow velocities of the internal carotid artery increased progressively, while the IR, IP and the S/D ratio decreased, between the evaluated periods (P1 and P2), providing greater flow in canine fetuses, maintaining normal heart rate, indicating positive fetal viability. Keywords: Doppler, gestational ultrasound, bitches, fetal circulation, umbilical artery, internal carotid, fetal middle cerebral artery

Comparative Study of the Vertebral Heart Scale (VHS) and the Cardiothoracic Ratio (CTR) in Healthy Poodle Breed dogs

Background: Veterinary cardiology has been widely divulged, especially because of the search for diagnostic methods that allow early identification of heart disease in companion animals. Several techniques are available, such as digital radiography (DR), computerized tomography (CT) and magnetic resonance (MR) that are being applied to patients with various diseases. VHS has been widely used in clinical practice in veterinary medicine as a way to diagnose heart size increases in lateral thoracic radiography in small animals. Cardiothoracic ratio (CTR) is a predictive factor for cardiac insufficiency in humans. In veterinary medicine, this index is still little used. The objective of the present study was to compare the vertebral heart scale (VHS) and cardiothoracic ratio (CTR) to assess changes in the size of the cardiac silhouette dogs in thoracic radiographs.Materials, Methods & Results: The VHS and CTR of forty healthy poodle breed dogs (20 males and 20 females) from University Veterinary Hospital at the Federal University of Piauí were assessed. The animals were placed in supine and lateral decubitus, to obtain radiographic images in dorsoventral (DV) and right and left laterolateral projections of the thoracic region. The images acquired on the photosensitive radiographic chassis were analyzed by digital radiographic image system installed in the Image Diagnosis Service of the University Veterinary Hospital -HVU/UFPI. VHS (Vertebral Heart Scale) measurements were taken using the sum of the heart length and heart width at its greatest diameter, comparing with the vertebral bodies from the fourth thoracic vertebra (T4). The CTR was assessed by comparing the greatest width of the heart silhouette and the distance between the thoracic walls at height T8. The heart width was measured from the two greatest distances (ML and MR), from the vertical line that divides the limit between the right and left sides of the heart, at the point of its greatest diameter. Similarly, the thoracic width was measured at the point of greatest thoracic diameter (MTD). The mean of the VHS and CTR in the males was 9.83 ± 0.85v and 0.48 ± 0.05, respectively. The females showed values of 9.65 ± 0.65v and 0.50 ± 0.03, respectively (P > 0.05). The mean of the VHS and CTR, considering males and females, was 9.72 ± 0.73v and 0.48 ± 0.04, respectively. VHS and weight correlated positively (r = 0.96), as the CTR and weight (r = 0.94). VHS and age showed high correlation (r = 0.96) as CTR and age (r = 0.93). VHS and CTR showed high correlation (r = 0.96).Discussion: Although congenital malformations and genetic diseases can occur, the acquired heart diseases correspond to most of the complications found in dogs. VHS increases considerably 6 to 12 months before the development of congestive heart failure (CHF). The poodles studied, considering the universe of males and females (P < 0.05), presented mean VHS values of 9.72 ± 0.73v. Similarly, there was no significant difference between genders for VHS measured in right and left decubitus in normal dogs. The cardiothoracic ratio measured for the poodles studied showed mean values of 0.48 ± 0.05. In humans, values below 0.5 are considered normal, while values above this may indicate the presence of cardiomegaly. The CTR is intimately related to the volume of the left ventricle and CTR values above 0.5 in humans are pathological. Our results demonstrated that VHS and CTR showed strong correlation in their measurements, suggesting that CTR, constantly used in humans, could be considered as a tool to assess the size of the heart silhouette in dogs of the poodle breed

Presumed Normal Hemodynamic Values of the Arteries in the Final Third Period of Gestation in Bitches

Background: Doppler ultrasonography enables the investigation of vascular blood flow indexes in gestational assessment, being able to detect vascular resistances that can affect fetal and maternal circulation, such as cases of placental insufficiency, associated with fetal cerebral oxygenation deficit and fetal distress. The study aims to assume hemodynamically normal values in the final third of gestation in bitches, of the umbilical, uteroplacental, middle cerebral and internal carotid arteries, correlating the obtained Doppler velocimetric indexes, for the assessment of the feto-placental circulation, and prediction of fetal viability indexes, fetal centralization and probable date of delivery.Materials, Methods &amp; Results: Thirty healthy bitches were examined in the final third of gestation (40-60 days). These were evaluated by Doppler ultrasonography at 2 times (T): T1: between 40-50 days; T2: between 51-60 of gestation. At each time point, the peak systolic velocities (PSV) and end-diastolic velocities (EDV) used to obtain the pulsatility (IP) and resistivity (IR) indexes of the umbilical, uteroplacental, middle cerebral and internal carotid arteries of fetuses were evaluated. Also, the systole/diastole (S/D) ratio of these vessels was evaluated. The data obtained were subjected to analysis of variance and Tukey test, using a P value equal to 5%. A significant difference was observed between velocities and Doppler velocimetric indexes between the 2 phases of the gestational final third in all studied vessels. There was an increase in the values of PSV and EDV and a decrease in the indexes, as the probable date of delivery approached. The analysis of the umbilical cord IR showed an increase from P1 to P2 (P &lt; 0.05), while the IP decreased at the same time. For all studied variables there was a statistically significant difference (P &lt; 0.05). In the uteroplacental artery, similarly to the umbilical artery, the PSV and EDV values showed an increase between P1 and P2, while the S/D ratio decreased up to 60 days of gestation (P2). The IR and IP of these vessels decreased during the study interval in pregnant bitches. The studied variables showed a statistically significant difference when analyzed comparatively between P1 and P2 (P &lt; 0.05). As for the middle cerebral artery and internal carotid artery, the PSV and EDV values increased until the end of pregnancy. Likewise, the Doppler velocimetric values and the S/D ratio decreased until the end of pregnancy (P2).Discussion: The hemodynamic values obtained for the umbilical artery and uterine artery were significantly different between 40 and 50 days of gestation (P1) and 50 and 60 days of gestation (P2), with a decrease in vascular resistance and an increase in velocities. It can be related to a greater association of maternal-fetal blood perfusion, due to the increased demand for the development of the fetus. The Middle Cerebral Artery (MCA) also showed changes between P1 and P2, with an increase in PSV and EDV in the final third of pregnancy, and the S/D ratio was reduced, differing significantly between P1 and P2. The systolic (PSV) and diastolic (EDV) flow velocities of the internal carotid artery increased progressively, while the IR, IP and the S/D ratio decreased, between the evaluated periods (P1 and P2), providing greater flow in canine fetuses, maintaining normal heart rate, indicating positive fetal viability. Keywords: Doppler, gestational ultrasound, bitches, fetal circulation, umbilical artery, internal carotid, fetal middle cerebral artery

Electrocardiographic Pattern of Agoutis (Dasyprocta prymnolopha) Chemically Contained by the Association of Ketamine and Xylazine

Background: The agouti (Dasyprocta prymnolopha, Wagler, 1831) is an existing wild rodent in almost all of Brazil, used as a biological model in several scientific studies. Veterinary cardiology has showed great advances in the diagnostic area due to the possibility of cardiac evaluation by non-invasive methods. For the practice of scientific or handling procedures in wild animals, chemical containment is essential. Thus, it is important to know the effect of anesthetic protocols on the cardiovascular system, observed through complementary tests, such as the electrocardiogram. The objective of this study was to describe the computerized electrocardiographic tracing of agoutis chemically contained by the association of Ketamine and Xylazine.Materials, Methods & Results: Eighteen male and female clinically healthy animals, aged among 2 years, submitted to digital electrocardiographic examination, were used. The device used to obtain the tracing was the veterinary electrocardiograph (Electrocardiogram Acquisition Module for Computer) - Brazilian Electronic Technology (TEB). The analysis was always made from derivation II (DII). Chemical containment was performed by the combination of Ketamine and Xylazine, intramuscularly. The results showed that the heart rate for males was on average 113.25 bpm, while for females the value of 124.60 bpm was observed, and there was no significant difference between the genders (P > 0.05). The mean weight of males was 2.31 kg and for females 2.28 kg; there was no statistical difference for this variable (P > 0.05). For the QRS duration of 46.14 ± 5.05 ms (males) and 44.66 ± 5.94 ms (females) and PR interval of 79.94 ± 12.01ms (males) and 84.29 ± 12.37ms (females), there was no statistical difference (P > 0.05). The amplitude of the R wave of 0.42 ± 0.31 mV (males) and 0.36 ± 0.22 mV (females) showed no statistical difference (P > 0.05). The T wave showed itself both negative (10 animals) and positive (8 animals), with amplitude measured at 0.24 ± 0.16 mV for males and 0.25 ± 0.10 mV for females (P > 0.05). The anesthetic protocol was well tolerated by the animals of this experiment, and there were no episodes of arrhythmias during the time of their monitoring.Discussion: Wild animals, in general, need chemical containment, with a view to reducing stress during scientific and handling procedures. The protocols established in this work can be used in future experiments which require a longer handling time. The values found for heart rate (HR) of anesthetized agoutis were lower than those for non-anesthetized agoutis, proving the influence of the stress during retention and the depressant cardiovascular effect of the anesthetic drug used. The electrocardiographic parameters and the tracing morphology of the agoutis were like the results found for anesthetized small rodents. The QT interval was higher in males than in females, justifying the fact that it could be influenced by variations in HR, which also showed superior results for males. Taking into consideration the morphological similarity between different individuals, the QT interval in anesthetized agoutis did not present significant differences between the genders, a characteristic also found in ferrets. The animals of this experiment were submitted to food fasting, a fact that contributed to a better standardization of the experiment, preventing alterations in the morphology of the QRS complex, which could lead to changes in the measurements