Mandibular morphometry applied to local anaesthetic blockage in the capybara (Hydrochoerus hydrochaeris).

Capybaras have been victims of collisions against vehicles, which can result in fractures of the teeth and mandible. Then, a local anaesthetic block of the inferior alveolar and mental nerves is important for performing therapeutic procedures in the oral cavity of these rodents. Thus, the aim of this study was to describe the mandibular morphometry of the capybara with emphasis on the establishment of anatomic references for anaesthetic block of the inferior alveolar and mental nerves. For this, mandibles from eight young and adult capybaras were used. Radiography and morphometry of the capybara hemimandible were performed. The mandibular foramen had a dorsoventral diameter of 2.1 mm in young and 2.2 mm in adult capybaras, and it was situated ventrally to the third molar tooth. For extraoral block of the inferior alveolar nerve, the needle should be introduced obliquely 63.5 and 77.4 mm from the angular process in young and adult capybaras, respectively. In another extraoral approach, the needle should be introduced perpendicularly 20.8 mm in young and 26.3 mm in adult animals from the ventral margin of the capybara mandible. For blocking only the mental nerve, the needle should be inserted perpendicularly from the interalveolar margin, 10.7 and 11.5 mm in the young and adult capybaras, respectively. The findings of this study suggest that the age group should be taken into account when performing the anaesthetic block of the inferior alveolar and mental nerves in capybaras.

Computed tomography and cross-sectional anatomy of the head in the giant anteater (Myrmecophaga tridactyla).

The aim of this study was to identify the anatomical structures in the head region of the giant anteater (Myrmecophaga tridactyla) using computed tomography. For this, three giant anteater corpses, adult and female, were used. The tomographic analysis was performed in sequential order in rostrocaudal direction. Subsequently, the heads of these animals were sectioned in cross sections of approximately 1.5 cm each. Tomographic images were compared with anatomical sections. The association between computed tomography and anatomical sections allowed the visualization of anatomical structures found in the nasal, oral, cranial, pharyngeal and ear cavities. An elongated oral cavity delimited by the elongated mandible was observed. The oral cavity was mainly occupied by a thin and elongated tongue formed mainly by the union of the sternoglossal muscles. The nasopharynx and oropharynx extended up to the neck at the level of the fifth cervical vertebra. The findings of this study suggest that the giant anteater has a head with structures morphologically adapted to its feeding habits, such as an elongated skull, tongue, styloid bones and mandible. In addition, based on the results of this study, it is possible to suggest that computed tomography is a pivotal tool for the veterinary routine of wild animals, since it allowed the identification of anatomical structures found in the head of the giant anteater.