This case report describes diagnosis, treatment, and outcome of maxillofacial trauma in a 9-week-old shih tzu. In addition to an open left mandibular body fracture and a right condylar process fracture, there were several relatively stable and minimally displaced right maxillary fractures. The torn soft tissues associated with the left mandibular body fracture were sutured closed, and a tape muzzle was placed. Due to sufficient fracture healing at the 2-week recheck examination, the tape muzzle was removed. The 6-week reexamination confirmed continued healing and recovery. Anesthesia was performed at the 5.5-month reexamination when the dog was 8 months old, revealing the presence of persistent deciduous teeth, linguoverted, malformed, and partially erupted permanent teeth, and asymmetric skeletal malocclusion (in addition to the breed-specific mandibular mesioclusion). Persistent deciduous teeth and linguoverted and malformed permanent teeth were extracted to allow for normal opening and closing of the mouth without traumatic occlusion. Long-term follow-up is recommended in juvenile dogs with maxillofacial injuries in order to prevent, recognize, and treat dental complications resulting from the trauma.

A cadaveric study was performed to investigate the external mechanical forces required to fracture maxillary fourth premolar teeth in domestic dogs and describe a clinically relevant model of chewing forces placed on functionally important teeth in which fracture patterns are consistent with those defined by the American Veterinary Dental College (AVDC). Twenty-four maxillary fourth premolar teeth were harvested from dog cadavers. Samples consisted of teeth with surrounding alveolar bone potted in polycarbonate cylinders filled with acrylic. The cylinders were held by an aluminum device at an angle of 60° with respect to the ground. An axial compression test was performed, creating a force upon the occluso-palatal aspects of the main cusps of the crowns of the teeth. The highest compressive force prior to failure was considered the maximum force sustained by the teeth. Results showed the mean maximum force (± SD) sustained by the tested teeth at the point of fracture was 1,281 N (± 403 N) at a mean impact angle (± SD) of 59.7° (± 5.2°). The most common fracture type that occurred among all samples was a complicated crown fracture (n = 12), followed by an uncomplicated crown fracture (n = 6), complicated crown-root fracture (n = 5), and uncomplicated crown-root fracture (n = 1). There was no statistically significant correlation between dog breed, age, weight, impact angle, crown height or crown diameter, and the maximum force applied at the point of fracture. The only independent variable that remained significantly associated with maximum force was the crown height to diameter ratio (p = 0.005), suggesting that a decreased ratio increases tooth fracture resistance. The methodology described herein has been successful in creating a pattern of fracture of maxillary fourth premolar teeth consistent with that defined by the AVDC under angled compression at forces within the maximum chewing capability of the average domestic dog.

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Medical records of dogs diagnosed with masticatory muscle myositis (MMM) at Ryan Veterinary Hospital of the University of Pennsylvania during a period of 17 years (from 1999 to 2015) were reviewed. Twenty-two dogs were included in this retrospective case series study. Immunosuppressive doses of prednisone were prescribed to all dogs. Twenty dogs had full recovery of masticatory function. The mean (SD) improvement in the vertical mandibular range of motion (vmROM) was 5.3 (3.1) cm during the first 4 weeks of treatment (weeks 1-4) and 2.8 (2.2) cm during the subsequent 8 weeks (weeks 5-12). The vmROM continued to improve for several more months. Six dogs had a relapse, but the clinical signs were more severe in dogs when no longer receiving prednisone compared to dogs still on prednisone at the time of relapse. When diagnosed and treated appropriately, MMM has a good prognosis with relatively quick return to masticatory function. Early discontinuation of prednisone therapy should be avoided. Approximately 1 year of therapy is recommended prior to discontinuing the medication. Educating the client about how to perform muscle palpation, determine vmROM at home, recognize signs of pain, and notice behavioral changes may help in the early detection of relapses.

This study was performed to report etiology, clinical presentation, and outcome of mandibular fractures in immature dogs treated with non-invasive or minimally invasive techniques. Immature dogs diagnosed with mandibular fractures from 2001 to 2016 were included in this study. Diagnosis of the mandibular fracture was achieved by oral examination and diagnostic imaging in the anesthetized dog. Twenty-nine immature dogs with 54 mandibular fractures were selected. Within the mandibular body, the regions of the developing permanent canine and first molar teeth were most commonly involved (46.4% and 35.0%, respectively). Within the mandibular ramus, 53.8% of the fractures were located in its ventral half, and 38.5% in the condylar process. Muzzling was applied in 72.4% of the dogs. All dogs had clinical healing with resolution of signs of pain and recovery of mandibular function. Mean time for clinical healing was 21 ± 9 days. Age of the dog and duration of muzzling were significantly associated with the time needed for clinical healing. In immature dogs, fractures of the mandibular body occur most commonly in the regions of the developing permanent canine and first molar teeth, while fractures of the mandibular ramus are most commonly found in its ventral half and the condylar process. Non-invasive or minimally invasive management of mandibular fractures in immature dogs carries a good prognosis regarding clinical healing and recovery of mandibular function. Dogs should be monitored for the development of dental abnormalities and/or skeletal malocclusion until permanent teeth have erupted and jaw growth is completed.