Received: 28 November 2017 Revised: 22 February 2018 Accepted: 8 March 2018 DOI: 10.1111/vru.12632 ORIGINAL INVESTIGATION The prevalence of medial coronoid process disease is high in lame large breed dogs and quantitative radiographic assessments contribute to the diagnosis Ayman Mostafa 1 Ingo Nolte 2 Patrick Wefstaedt 2 1 Small Animal Hospital, College of Veterinary Medicine, Cairo University, Giza, Egypt 2 Small Animal Hospital, University of Veterinary Medicine, Hannover, Foundation, Hannover, Germany Correspondence Ingo Nolte, Small Animal Hospital, University of Veterinary Medicine, Hannover, Foundation, Bünteweg 9, 30559 Hannover, Germany. Email: ingo.nolte@tiho-hannover.de Funding information Bilateral Exchange of Academics and Sci- entists program; Deutscher Akademischer Austauschdienst Abstract Medial coronoid process disease is a common leading cause of thoracic limb lameness in dogs. Computed tomography and arthroscopy are superior to radiography to diagnose medial coro- noid process disease, however, radiography remains the most available diagnostic imaging modal- ity in veterinary practice. Objectives of this retrospective observational study were to describe the prevalence of medial coronoid process disease in lame large breed dogs and apply a novel method for quantifying the radiographic changes associated with medial coronoid process and subtrochlear-ulnar region in Labrador and Golden Retrievers with confirmed medial coronoid pro- cess disease. Purebred Labrador and Golden Retrievers (n = 143, 206 elbows) without and with confirmed medial coronoid process disease were included. The prevalence of medial coronoid process disease in lame large breed dogs was calculated. Mediolateral and craniocaudal radio- graphs of elbows were analyzed to assess the medial coronoid process length and morphology, and subtrochlear-ulnar width. Mean grayscale value was calculated for radial and subtrochlear- ulnar zones. The prevalence of medial coronoid process disease was 20.8%. Labrador and Golden Retrievers were the most affected purebred dogs (29.6%). Elbows with confirmed medial coronoid process disease had short (P < 0.0001) and deformed (∼95%) medial coronoid process, with asso- ciated medial coronoid process osteophytosis (7.5%). Subtrochlear-ulnar sclerosis was evidenced in ∼96% of diseased elbows, with a significant increase (P < 0.0001) in subtrochlear-ulnar width and standardized grayscale value. Radial grayscale value did not differ between groups. Periar- ticular osteophytosis was identified in 51.4% of elbows with medial coronoid process disease. Medial coronoid process length and morphology, and subtrochlear-ulnar width and standardized grayscale value varied significantly in dogs with confirmed medial coronoid process disease com- pared to controls. Findings indicated that medial coronoid process disease has a high prevalence in lame large breed dogs and that quantitative radiographic assessments can contribute to the diagnosis. KEYWORDS canine, elbow abnormality, quantifying, radiographs 1 INTRODUCTION Medial coronoid process disease is the most common heritable, developmental disease causing elbow dysplasia and secondary osteoarthritis in medium-to-giant breed dogs. 1–5 Medial coronoid pro- cess disease is a leading cause of thoracic limb lameness in young, adult, and old dogs. 6–8 Other hereditary diseases of the elbow joint include ununited anconeal process, osteochondrosis of the medial humeral condyle, articular cartilage anomaly, and joint incongruence. 2,9–11 Medial coronoid process disease most likely develops due to short radius incongruity, whereas an ununited anconeal process develops secondary to short ulna incongruity. 4,9,12 Elbow joint incongruity is not always identified at the time of diagnosis of both diseases. 1,13,14 Medial coronoid process disease develops secondary to a disturbance of endochondral ossification of the medial coronoid process with associated retained hyaline cartilage formation. 15 The increased pressure or shearing forces during joint movement or secondary to elbow joint incongruity may cause formation of cracks between the retained hyaline cartilage and subchondral bone or even complete detachment of the coronoid process. 4,15,16 The disease is, therefore, Vet Radiol Ultrasound. 2018;1–13. c  2018 American College of Veterinary Radiology 1 wileyonlinelibrary.com/journal/vru