Monocular retinopathy of prematurity-like retinal vasculopathy in a dog

Purpose: To describe a case of monocular retinopathy of prematurity (ROP)-like vasculopathy without oxygen supplementation in the dog. Methods: Fundus photographs (RetCam), spectral-domain optical coherence tomography (sdOCT), confocal scanning laser ophthalmoscopy (cSLO), and fluorescein angiography (FA), as well as postmortem histology and immunohistochemistry (Collagen IV and anti-vWF antibodies), were carried out to characterize the vascular abnormalities. Results: Ophthalmic examination showed peripheral and mid-temporal avascular areas in the tapetal region, neovascularization and abnormally dilated and tortuous retinal vessels in the left eye. sdOCT demonstrated not only cross-sectional views of preretinal fibrovascular proliferation but also extensive proliferation extraretinally into the vitreous. FA emphasized demarcation of vascular and avascular zones with neovascular tufts “popcorns.” Histology and immunohistochemistry confirmed presence of abnormally dilated vessels and the intravitreal blood vessels. Conclusions: ROP is a disease of abnormally developed retinal vascularization associated with oxygen supplementation therapy, potentially causing blindness in premature infants. Although the mechanism of ROP-like vasculopathy in our case is unclear, it is important to appreciate that the abnormal vascular pattern seen in ROP in premature infants can occur in canines without oxygen administration.