The temporomandibular joint is found bilaterally in all mammalian species, but its morphology and function are very different among different groups of mammals. In addition to chewing, this joint plays an important role in swallowing, oral health, nutrition and animal survival. The temporomandibular joint structure is formed by the connection between the condylar process of the mandible and the mandibular fossa of the squamous part of the temporal bone. Dysplasia is a rare abnormality of temporomandibular joint which can be congenital or developmental and it has been reported sporadically in a series of dog breeds, and the occurrence of this disorder is less in cats. Dysplasia often results in luxation or subluxation of the joint associated with locking of the open jaw. The current study is a case report of an 11.5 year old male terrier dog, which clinically had a history of pain in the mouth, difficulty in chewing, and reduced the ability of mouth movements. In this study, CT scan was used to evaluate the temporomandibular joint dysplasia. After performing a CT-scan and examining the images, temporomandibular joint dysplasia was diagnosed bilaterally with more severely in the right joint. In CT images, deformation of the retroarticular process, elimination of smooth joint surfaces, deformation of the joint surfaces of the mandibular condyle with S- shaped appearance, and the ambiguous joint space were observed which indicated temporomandibular joint dysplasia. Also, flattening of the retroarticular process was observed in the CT-scan images in reconstructed sagittal plane.