B-Mode and Doppler Ocular Ultrasound Evaluation in Healthy and Positive Dogs for Visceral Canine Leishmaniasis

Abstract

Background: The use of ultrasound examination in the evaluation of ophthalmopathies has been gaining more and more space within the ophthalmologic clinical routine. The hemodynamic study of ocular vascularization may anticipate future changes, aiding in the adequate establishment of therapeutic conduits. The objective of this study was to evaluate the structures of the ocular bulb and to perform the hemodynamic evaluation of the flow of the external ophthalmic artery of dogs with canine visceral leishmaniasis (CVL) correlating with healthy animals.Materials, Methods & Results: For this purpose, 100 animals were used, of these 70 positive for CVL and 30 healthy animals, submitted to B-mode and Doppler ultrasound examination. Two-dimensional evaluation included identification of ocular changes and biometry of the following segments: axial length (M1), anterior chamber depth (M2), lens thickness (M3), lens length (M4), glass chamber depth (M5), optical disc length (M6) and optic nerve length (M7). The Doppler velocimetric evaluation included the identification and hemodynamic evaluation of the external ophthalmic artery, being measured: systolic peak velocity (SPV), final diastolic velocity (FDV), resistivity index (RI) and pulsatility index (PI). Ophthalmopathies were frequent in animals with leishmaniasis in both right (91.42%) and left (29.14%) eyes, with identification of capsular cataract, lens dislocation, retinal detachment and lens rupture. No significant statistical difference (P > 0.05) was observed when comparing the biometric values between the right and left eyes of the animals with CVL, as well as for the measurements between healthy and CVL animals. Hemodynamic indexes of the flow of the external ophthalmic artery presented narrow limits for the right and left eyes of the positive animals, not statistically different from each other. However, a significant difference was observed when compared to hemodynamic evaluations of the flow of the ophthalmic artery between the right eyes of the group of normal animals and that of the carriers of leishmaniasis, with the latter presenting values superior to the first one. The B-mode and Doppler ultrasonographic evaluation enabled the morphological characterization of the ocular bulb, the identification of ophthalmopathies and the hemodynamic evaluation of the external ophthalmic artery of dogs with canine visceral leishmaniasis, establishing values that could be used in clinical ophthalmologic routine.Discussion: The presence of ocular changes diagnosed by B-mode ultrasonography were common in dogs with canine visceral leishmaniasis. Ocular lesions were observed in 80.5% of dogs with leishmaniasis, presenting a high frequency, corroborating with the results in the present research. In 22% of the animals, B-mode ultrasonographic lesions were identified in both eyes, 64 of these presented changes only in the right eye and 16 in the left eye. Ophthalmopathies can be uni or bilateral and cause more than one alteration in the same eye, resulting from both the immune-mediated mechanisms caused by the agent and direct parasitism. Although the literature reports that the highest frequency of lesions is bilateral, only 16 animals had alterations in both eyes. The origin of ophthalmopathies may be related to the species and tropism of the parasite, type and duration of the immune response developed by the host. The greater frequency of bilateral ophthalmopathies can have correlation with the systemic disease, in which in the initial stages of the disease only one eye is affected and the occurrence of bilateral manifestations is related to the chronic cases.