In brachycephalic dogs, the skull bone shortening is not paralleled by a decreased development of soft tissues. Relatively longer soft palate is one of the main factors contributing to pharyngeal narrowing during normal respiratory activity of these dog breeds, which are frequent carriers of the brachycephalic airway obstructive syndrome (BAOS), which affects most part of them during their postnatal life. No histological studies assessing the morphology and the normal tissue composition of the soft palate in brachycephalic dogs are available, neither has ever been determined whether the elongated soft palate is a primary or secondary event. Aim of this study was to describe the morphology of the caudal soft palate in brachycephalic dogs with Grade I BAOS to identify potential features possibly favoring the pathogenesis of BAOS. Specimens from brachycephalic dogs (N ¼ 11) that underwent preventive surgery were collected from surgery, processed for histology, and examined at six transversal levels. The brachycephalic soft palates showed peculiar features such as thickened superficial epithelium, extensive oedema of the connective tissue, and mucous gland hyperplasia. Several muscular alterations were evidenced in addition. The results of this investigation add to the general knowledge of the anatomy of soft palate in the canine species and establish baseline information on the morphological basis of the soft palate thickening in brachycephalic dogs. Anat Rec, 294:1267Rec, 294: -1272Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.

A thickened and abnormally long soft palate is mostly involved in the pathogenesis of both nasopharyngeal and oropharyngeal narrowing, affecting the respiratory activity in virtually all of the brachycephalic dogs suffering from Brachycephalic Airway Obstructive Syndrome (BAOS). The morphology of the soft palate in adult mesaticephalic and brachycephalic dogs has been previously described. In this article specimens from brachycephalic dog neonates (N 5 10) dead from one to 3 hr after birth of unrelated conditions were collected and histologically evaluated at three transverse levels to describe the microscopic aspect of the caudal part of the soft palate. The soft palate of neonate brachycephalic dogs was histologically characterized by a musculoconnective axis containing salivary glands and coated by a mucosal layer on both the nasopharyngeal and the oral side. Quali-quantitative features, such as thickened superficial epithelium, broad oedema of the lamina propria, mucous gland hyperplasia and diverse muscular modifications described in adult brachycephalic dogs, were not observed in the soft palate of brachycephalic neonate dogs. The lack of tissue lesions in the soft palate of newborn brachycephalic dogs further supports the hypothesis that inspiratory depression during the inspiratory phase causes chronic vibration and microtrauma, which lead to soft palate alterations in adult brachycephalic dogs starting from the earliest grade of the respiratory syndrome. Overall, this study provides baseline information for the comprehension of the pathogenesis of BAOS. Anat Rec, 298:618-623, 2015. V C 2014 Wiley Periodicals, Inc.

The gross anatomy and overall structure of the soft palate has been described in the average dog's head, however, no descriptive microanatomical studies of the dog soft palate are available, despite their possible utility in view of the manifold and important repercussions of this organ physiology. This is the first of two companion papers, dealing with the caudal part of the soft palate in the canine species, in mesaticephalic and brachycephalic dogs. Specimens from mesaticephalic healthy dogs (N ¼ 8) were collected after euthanasia, processed for histology and sectioned at six transversal levels. Morphological stainings were used for a microscopic evaluation of the tissue layers composing the distal part of the soft palate in adult mesaticephalic dogs, and histochemical reactions were applied to assess mucin types within glandular tissue and to investigate the connective tissues. The organ was characteristically organized into a major deep musculo-connective axis mixed with salivary glands and covered by the mucosal lining on either the nasopharyngeal or the oral sides. The results of this investigation add to the general knowledge of the anatomy of soft palate in the canine species and establish baseline information for the parallel study on the long and thickened soft palate, which is typical of adult brachycephalic dogs. Anat Rec, 294:1261Rec, 294: -1266Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.