Osteitis deformans (Paget’s disease) is a chronic bone disorder characterized by excessive osteoclast-mediated bone resorption followed by new bone formation. The present paper reports this condition in an 18-year-old captive golden lancehead (Bothrops insularis) from Brazil. This patient initially exhibited anorexia and swelling in the middle third of the spine associated with locomotor disability. For diagnosis, radiography, ultrasound, computed tomography, cytology, and microbiological culture were performed. Diagnostic imaging showed bone changes, vertebral fusion, and bone proliferation. Cytology revealed blood cells how toxic heterophiles, reactive monocytes, young red blood cells, and polychromasia compatible with an infectious process. A bacterial culture identified an ampicillin-susceptible strain of Enterococcus faecalis. Antibiotic treatment was promptly started, but the snake died 25 days later. Histopathologically, the bone tissue showed a generalized thickening of the vertebral trabeculae. For the first time, the presence of E. faecalis associated with the development of osteitis deformans in snakes was presented.