OBJECTIVE: To evaluate the long-term outcome of endoscopic cyclophotocoagulation (ECP) for the treatment of primary and secondary glaucoma in dogs. ANIMALS STUDIED: Retrospective review of dogs that underwent ECP at two referral centers from 2004 to 2023. PROCEDURES: Medical records of 389 eyes (301 dogs) following ECP were reviewed. Outcomes evaluated included follow-up time, intraocular pressure (IOP), vision status, additional ECP procedures performed, number of medications, and complications. Patient and surgical variables and their association with IOP control and vision maintenance were evaluated. RESULTS: Median follow-up time was 18 months. IOP remained controlled in 90% and 95% of patients at 1 and 2 years, respectively, following ECP. IOP was controlled long-term (2 years) in cases with primary (88%) and secondary (99%) glaucoma. Post-operative vision was maintained in 63% and 49% of eyes at approximately 1 and 2 years, respectively. Median time to vision loss was 6.5 months. Repeat ECP was required in 15.4% of eyes at a median of 19 days post-operatively. Eyes that underwent more than one ECP surgery had a significantly longer median time to blindness (13.8 months) than those that underwent a single ECP procedure (3.6 months
p = .0003). The median number of anti-glaucoma medications decreased from three pre-operatively to one at 1- and 2-year post-operatively. Complications included corneal ulceration (28%), blinding hypotony (11%), retinal detachment (11%), and hyphema (10%). CONCLUSION: Endolaser cyclophotocoagulation is an effective surgery for maintaining long-term IOP control and extending vision in canine patients with glaucoma refractory to medical management.