BACKGROUND: Impingement of the dorsal spinous processes is a common cause of pain and poor performance in sport horses.OBJECTIVES: This study was performed to evaluate the prevalence of impingement in dorsal spinous processes and the correlation between the occurrence of this complication and certain parameters, such as age, height, weight, discipline, breed, neck length, and clinical signs.METHODS: In this study, radiographic examination of the spine of 50 horses were performed. The information about height, weight, discipline, breed, neck length, and clinical signs were also collected. Radiographic grading was based on the degree of the changes in inter spinous spaces and their densities (0-4 degrees). The clinical examinations were carried out to evaluate the pain in the spine. Statistical analysis was performed to investigate the correlation between the collected data.RESULTS: The highest incidence of impingement was seen in the middle thoracic area. There was a significant correlation between the occurrence of impingement and age and the breed of the studied horses. There was no correlation between the incidence of impingement and sex, height, neck length, and weight of the studied horses.  Increased radiographic grade often leads to an increase in the severity of clinical signs. A higher grade of radiographic sign in each horse was indicative of more involved inter spinous spaces.CONCLUSIONS: According to the results of this study, Grade 3 and 4 had high specificity with clinical signs; therefore, preparation of a radiograph of the spine before purchasing a horse could be highly recommended.