Christopher J. Snyder

Effect of mepivacaine in an infraorbital nerve block on minimum alveolar concentration of isoflurane in clinically normal anesthetized dogs undergoing a modified form of dental dolorimetry

OBJECTIVE To evaluate the effects of a routinely used infraorbital nerve block, performed for dental procedures, on the anesthetic requirement for isoflurane in dogs. DESIGN Prospective controlled study. ANIMALS 8 healthy adult Beagles. PROCEDURES Dogs were anesthetized with isoflurane, and the minimum alveolar concentration (MAC) of isoflurane was established. A modification of a well-established method of stimulating the dental pulp, dental dolorimetry, was used to deliver a noxious stimulus (electrical stimulation) for isoflurane MAC determination. Once the isoflurane MAC was established, an infraorbital nerve block was performed with mepivacaine. The isoflurane MAC was then determined with the addition of the nerve block. Measurements of heart rate and mean arterial blood pressure were obtained at specified time points (baseline and prevention and elicitation of purposeful movement) during the determination of MAC and in response to the noxious stimulus. RESULTS The mean ± SD isoflurane MAC without an infraorbital nerve block was 1.12 ± 0.13%. Isoflurane MAC with the regional mepivacaine anesthesia was 0.86 ± 0.11%. A significant reduction in isoflurane MAC (23%) was seen after the infraorbital nerve block, compared with results before the nerve block. With the exception of baseline measurements, no significant differences were found between treatments (isoflurane alone vs isoflurane with regional mepivacaine anesthesia) in heart rate or mean arterial blood pressure before or after the noxious stimulus. CONCLUSIONS AND CLINICAL RELEVANCE The significant reduction in MAC of isoflurane supported the practice of the addition of regional anesthesia for painful dental procedures to reduce the dose-dependent cardiorespiratory effects of general anesthesia.

Prevalence and nature of dentoalveolar injuries among patients with maxillofacial fractures

OBJECTIVE Although not previously reported, experience suggests that dentoalveolar injury is -common among patients with maxillofacial fractures. The objective of this study was to evaluate and describe the prevalence and nature of dentoalveolar injuries in patients identified with maxillofacial fractures. METHODS Medical records of 43 dogs and cats diagnosed with maxillofacial fractures between 2005 and 2012 were reviewed to identify patients with concurrent dentoalveolar injury. Medical records of patients with dentoalveolar injury were abstracted for the following information: signalment (including sex, age and skull type), mechanism of maxillofacial trauma, location and number of maxillofacial fractures, dentoalveolar injury type and location and the number of dentoalveolar injury per patient. Statistical evaluation was performed to determine associations between signalment, mechanism of trauma, location and number of maxillofacial fractures and the prevalence and nature of concurrent dentoalveolar injury. RESULTS Dentoalveolar injuries are common among patients with maxillofacial trauma. Age and mechanism of trauma are significant predictors of the presence of dentoalveolar injuries in patients with maxillofacial trauma. CONCLUSIONS AND CLINICAL RELEVANCE The findings of this study serve to encourage veterinarians to fully assess the oral cavity in patients with maxillofacial fractures as dentoalveolar injuries are common and can be predicted by age and mechanism of trauma.

Surgical treatment of a rostral mandibular complex odontoma in a 3-year-old horse

Summary Complex odontomas are rare odontogenic tumours in horses comprised of a combination of mesenchymal and epithelial tissues. Examination, radiographic and histopathological findings in this patient all represent the typical behaviour of a complex odontoma. Oral tumours in horses may have treatment limitations due to tumour size and location. Similar to treatment in other species, surgical enucleation was curative for this type of tumour.

Clinical, Histologic, and Computed Tomographic Features of Oral Papillary Squamous Cell Carcinoma in Dogs: 9 Cases (2008–2011)

Medical records of dogs diagnosed with oral papillary squamous cell carcinoma between December 2008 and April 2011 were reviewed. Information abstracted included signalment, tumor location, tumor size, computed tomographic (CT) features, evidence of metastatic disease based on cytologic examination of lymph node aspirates and thoracic radiography, treatment, surgical margins, histologic features, and treatment outcome. Dogs included in the study were all sexually altered, predominantly large breed dogs with a mean age of 3.9-years (range, 0.5 to 9.0-years). The most common location was the rostral maxilla. Invasion of underlying bone and lymphadenopathy were evident on CT imaging in most dogs. No evidence of metastasis was found on mandibular lymph node cytology and thoracic radiography. Histologic analysis revealed similar morphologic findings for all surgically resected tumors. Surgical excision with 1–2 cm margins was complete in all cases, with a mean tumor-free interval of 12.1-months.

Imaging and management of a caudal mandibular fracture in an immature dog.

Interfragmentary wire surgical technique was used to repair a caudal mandibular fracture in a 15-week-old Labrador Retriever dog. Computed tomographic imaging aided the diagnosis and treatment planning for the application of this method. Abnormal tooth development of caudal molar teeth was related to the traumatic event and/or surgical technique. The strategically important mandibular first molar tooth was maintained. The fracture fixation method used in this case provided early return to function and radiographic evidence of expected fracture healing during a 10-month period despite wire displacement secondary to tooth eruption.

Caudal Mandibular Bone Height and Buccal Cortical Bone Thickness Measured by Computed Tomography in Healthy Dogs

OBJECTIVE To characterize bone height and buccal cortical bone thickness of the caudal mandible of healthy dogs. STUDY DESIGN Prospective original study. SAMPLE POPULATION Client-owned dogs (n = 36). METHODS Dogs were distributed by weight into 3 groups (<10, 10-20, >20 kg). Thirteen transverse plane computed tomography images were selected for each dog based on anatomic landmarks from the 4th premolar (PM4) through the 2nd molar. On each image, bone thickness was measured along the buccal surface of both mandibles from the alveolar margin to the ventral border in 3 mm increments. The number of 3 mm increments were recorded as an estimation of mandibular height. RESULTS Buccal bone was generally thicker ventrally in the area studied with decreasing bone thickness over both roots of PM4 and the mesial root of the 1st molar (M1). Cortical bone thickness of <2.0 mm was measured across all groups at most locations 3 mm ventral from the alveolar margin. Mandibular bone height demonstrated significantly fewer (P < .05) 3 mm increments over the distal root of M1 in dogs >10 kg compared with the number of observations at the immediately mesial and distal locations. CONCLUSION Thin cortical bone overlying the mesial and distal roots of PM4 and the mesial root of M1 limits use of these areas for application of monocortical anchorage devices. Decreased mandibular bone height at mandibular M1 may create a stress riser at this location, which along with thin cortical bone may explain why this is a common area for mandibular fracture.

Effect of Preparation Surface Area on the Clinical Outcome of Full Veneer Crowns in Dogs

Crown therapy is commonly used in veterinary medicine to provide support to teeth which have previously fractured, received root canal therapy, have significant wear, or experienced other detrimental removal of tooth substance. As with several aspects of veterinary medicine, many of the recommendations or guidelines for crown therapy originate from human dentistry, which are then transferred to veterinary patients. Due to the significant difference in the anatomy of teeth and function of the oral cavity between humans and dogs, these guidelines need to be studied to determine the appropriateness of their use in veterinary patients. This article evaluates the relationship between surface area of the preparation and clinical outcome of full veneer crown therapy of the canine tooth in dogs. Although there appeared to be a positive relationship between preparations with greater surface area and successful clinical outcome, it was not found to be statistically significant.

Use of an autogenous cortical graft in combination with guided tissue regeneration for treatment of an infrabony defect.

Infrabony periodontal defects are common findings encountered during complete oral examinations. Treatment options for infrabony lesions are aimed at meeting client demands as well as patient needs. Deciding on how to treat these lesions depends on the nature and degree of disease present as well as having the materials available to improve the chances of achieving the greatest clinical success. Bone grafting of an infrabony defect of the left mandibular first molar tooth of a dog using an autogenous cortical graft harvested with a reusable bone grafter in combination with guided tissue regeneration is described.

Transmylohyoid Orotracheal Intubation in Surgical Management of Canine Maxillofacial Fractures: An Alternative to Pharyngotomy Endotracheal Intubation

OBJECTIVE To describe the surgical technique of transmylohyoid orotracheal intubation in surgical management of maxillofacial fractures in dogs. STUDY DESIGN Case series. ANIMALS Dogs (n = 4) with maxillofacial fractures. METHODS Transmylohyoid orotracheal intubation was used for airway management of dogs undergoing surgical repair of maxillofacial trauma. A stoma was surgically created by an incision through the skin, subcutaneous tissue, and mylohyoideus muscle immediately medial to the lingual cortex of the mandible at the level of the mandibular 1st molar tooth, so that an endotracheal tube could exit the oral cavity between the mandibular bodies bypassing the dentition. RESULTS Transmylohyoid orotracheal intubation allowed excellent surgical visibility of the oral cavity and intraoperative control of occlusion during surgery. No complications were encountered during the procedure and the stoma healed without complication. CONCLUSIONS Transmylohyoid orotracheal intubation is a safe, simple, and effective technique for bypassing the rostral oral cavity and dentition during surgical management of maxillofacial fractures.

Retrospective evaluation of canine and feline maxillomandibular trauma cases. A comparison of signalment with non-maxillomandibular traumatic injuries (2003-2012)

OBJECTIVES To determine differences in signalment between maxillomandibular (MM) and non-maxillomandibular (non-MM) trauma patients to help predict the type of injury sustained. METHODS A medical records database was searched from December 2003 to September 2012 to identify all MM trauma patients. A random sample of non-MM trauma patients was generated for comparison. Patient species, age, sex, weight, and injury aetiology were recorded for both populations. RESULTS Sixty-seven MM trauma patients and 129 non-MM trauma patients were identified. Feline patients were almost twice as likely to be presented for MM trauma compared with non-MM trauma. The median weight of canine patients suffering MM injury was significantly less than that of non-MM patients (p = 0.025). A significant association existed between the causes of injuries associated with MM and non-MM trauma populations (p = 0.000023). The MM trauma patients were more likely to sustain injury as a result of an animal altercation (Bonferroni p = 0.001) while non-MM injuries were more likely to result from motor vehicle accidents (Bonferroni p = 0.001). Overall, animals that were less than one year of age with traumatic injuries were overrepresented (65/196) in comparison to the entire patient population. CLINICAL SIGNIFICANCE The results of this study may help guide clinicians in the evaluation and screening of trauma patients that are presented as an emergency. Cats, small dogs and animals suffering from animal altercations should all be closely evaluated for MM injury.