Dental Anomaly causing Severe Maxillary Lesions in a Male Sowerby’s Beaked Whale, Mesoplodon bidens (Sowerby, 1804)

Sowerby’s beaked whale (Mesoplodon bidens) is a poorly known cetacean species and much of what we know about it comes from stranded animals. Here, we describe a dental anomaly in an adult male stranded in 2019 in the Moray Firth, Scotland. The mandibular teeth (tusks) had erupted so their tips converged towards the median plane and they did not protrude over the lips laterally as is normal in adult male M. bidens. As a result the tusks were causing severe damage to the palate by continual mechanical stimulus. The symmetrical nature of the pair of tusks suggests a developmental abnormality. This malignment of the teeth and damage to the soft tissue and underlying bone of the rostrum, likely negatively impacted the health of the animal, increasing the risk of infection.