SUMMARY: Brachycephalic Obstructive Airway Syndrome (BOAS) is defined as respiratory distress caused by cranial shortening in dogs, called paedomorphism, which leads to morphological alterations in the upper airway causing its obstruction. From this condition, morphological alterations occur in the upper respiratory airways (URA) that can cause obstruction, leading to a permanent increased inspiratory effort. Stenotic nares, aberrant nasal turbinates as well as soft palate elongation and thickening are recognized as primary anatomical abnormalities leading to obstruction. Clinically, it manifests with added respiratory sound and exercise intolerance, limiting activities of the affected dogs. BOAS can be diagnosed by complementing anamnesis and clinical examination with the use of imaging. Despite medical approaches described, the definitive solution is surgical correction of the anatomical abnormalities causing BOAS. Therefore, the aim of this study was to perform an updated bibliographic review of the anatomical alterations of URA affecting dogs with BOAS, as well as the associated clinical signs and surgical treatment. A total of 47 bibliographic sources were used: 38 scientific journal articles, 6 books and 3 online resources. Since there is a direct relationship between the degree of brachycephaly and the BOAS presentation, it is necessary to establish limits to paedomorphism at kennels based on objective parameters such as CFR or IC (Craniofacial Ratio and Cranial Index, respectively).

KEY WORDS Brachycephalic Syndrome; Paedomorphism; Canine upper airway anatomy; BOAS corrective surgery; Animal Welfare.