Evaluating dogs’ eyes with contrast-enhanced ultrasonography

Ocular blood perfusion can be evaluated by various imaging modalities and is an important parameter when the differential diagnosis list includes neoplasia. In fact, as pathologic angiogenesis is considered a hallmark of ocular tumours, contrast-enhanced ultrasonography (CEU) is also used in human medicine.

CEU shows advantages over both Colour and Power Doppler, especially when you need to detect the blood flow of smaller vessels, where the volume of blood is lower and circulation slower.

In this unique study, the right eyes of eight clinically healthy beagles were examined. After anesthetizing the dogs with zolazepam and medetomidine they were positioned in sternal recumbency and examined by ultrasonographies using B-mode, Colour Doppler, Power Doppler and contrast. The vascularization in the anterior segment, in the posterior segment of the eyeball and in the retrobulbar region was quantitatively analyzed, based on the number of vascular signs.

CEUs identified signals that were not seen with Doppler when investigating both vessels of the ciliary body and the iris and smaller ones around the posterior segment from the retina choroid and sclera.

Aside from the possible influence of anaesthetics in time-intensity curve parameters, this study is a useful tool for the future development of veterinary practice in this area. Effectively, the authors of this study provide a canine ophthalmic CEU examination protocol and define quantitative reference values for the ciliary body, iris, retina, choroid and retrobulbar area in normal dogs – tools that may serve as a reference for further investigations, not only into intraocular tumours but also into canine retinal pathologies.

Hong S, Park S, Lee D, Cha A, Kim D, Choi J. Contrast-enhanced ultrasonography for evaluation of blood perfusion in normal canine eyes. Vet Ophthalmol. 2018;00:1–8. https://doi.org/10.1111/vop.12562