Anatomic characterization of pulmonary accessory fissures in canine cadavers.

Accessory fissures in the lungs are well described in humans, considered a normal finding, being identified in 60% of autopsied lungs, and more prevalent in the right lung (Gesase, ; Nene, Gajendra, & Sarma, 2011). In dogs, interlobar fissures are well recognized, but there is the lack of anatomic characterization for accessory fissures in the accessible literature. The purpose of this descriptive study was to identify the prevalence and to describe the anatomic localization of accessory fissures. The lungs from 87 dog cadavers used to teach veterinary gross anatomy were collected. Accessory fissures were characterized for each lung lobe, specific lung lobe location, orientation, length and the number of accessory fissures per lobe. Accessory fissures were recognized in 48/87 (55%) of canine lungs, all located in the periphery of the individual lobes. We found a significant association between the presence of accessory fissures and the costal surface of the lung (p < 0.0001), the right lung (p < 0.004), the right cranial lung lobe (p < 0.002) and the left cranial lung lobe (p < 0.04). Histologic results showed normal alveolar and respiratory bronchioles to the level of the accessory fissures. Our results show that accessory fissures are a common finding and should be considered a normal variant. They are more prevalent in the right lung, in the costal surface, and in the right and left cranial lung lobes. An anatomic nomenclature for accessory fissures based on the current Nomina Anatomica Veterinaria and the human literature is proposed. Further studies include a comparison among anatomical accessory fissures, and radiographic and computed tomographic images.