Retrospective Study of Clinically Relevant Maxillary and Mandibular Anatomy in all Skull Types of the Dog and Cat

Erinn Schellenberg^*Candace Lowe

• University of Saskatchewan Western College of Veterinary Medicine, Saskatoon, Canada

In this retrospective study, Computed Tomography (CT) was used to examine the images of 193 dogs and 41 cats which were divided into mesocephalic (≤5kg, 6-10kg and ≥11kg), brachycephalic (≤10kg, ≥11kg), dolichocephalic (≤10kg, ≥11kg) dogs, and mesocephalic and brachycephalic cats. Mean, minimum and standard deviation were calculated for the infraorbital canal length, width and height, shortest distance from the infraorbital foramen to the globe, maxillary foramen to the globe, shortest distance from the root apex of the maxillary first and second molar teeth to the globe in dogs, shortest distance from the root apices of the maxillary fourth premolar tooth to the globe in cats, shortest distance from the end of the hard palate immediately caudal to the maxillary second molar tooth in dogs and maxillary first molar tooth in cats to the globe and the maxillary foramen. Values were tabulated and combined into reference materials to aid veterinarians in decision making with respect to infraorbital, maxillary and mandibular nerve blocks, maxillary extractions, and maxillary and mandibular surgical procedures. Our findings revealed caution should be used when performing infraorbital and maxillary nerve blocks in mesocephalic and dolichocephalic dogs weighing less the 10kg and all cats. Large brachycephalic dogs weighing more than 11kg may be at lower risk of accidental globe trauma during infraorbital nerve block. The deep maxillary nerve block should not be used on cats and small dogs. The maxillary nerve block using the modified infraorbital canal approach combined with the recommended safe distances (Table 9) should provide safe and effective analgesia administration. Mean measurements for distances from the distal aspect of the mandibular third molar tooth crown in dogs and the mandibular first molar tooth crown in cats, to the mandibular foramen, and lastly from the end of the palate, immediately caudal to the last molar tooth, to the maxillary foramen. These results may be used for surgical planning and ligation for hemostasis for caudal mandibulectomies and maxillectomies, particularly when CT imaging is not available.