Structural characteristics of the nose in brachycephalic dog breeds analysed by computed tomography

In brachycephalic dogs breeds exaggerated and incorrect breed selection has led to overemphasis of brachycephaly and almost complete loss of the nose. This structural deformity causes severe malfunction of the airway and thus brachycephalic airway syndrome (BAS). It was the aim of this study to examine the anatomical specifics of the brachycephalic nose by computed tomography (CT) and to compare them to those of the normocephalic nose.

A total of 23 brachycephalic dogs (11 pugs, seven French Bulldogs, five English Bulldogs) and one normocephalic German Shepard dog as reference were examined. Multislice CT images of all animals were analysed. First multisclice images of both nose types were generated. Then, to compare structural differences to normocephalic breeds and among brachycephalic breeds, anatomical parameters were recorded and derived.

Extreme shortening of the craniofacial skull and thus of the nasal cavity leads to abnormal configuration of the conchae. Two main types of aberrant conchal growth have been described: 1. rostral, aberrant conchae obstructing the nasal passage (RAC) and 2. caudal aberrant conchae obstructing the choanae (CAC). Furthermore, these conchae are characterised by a low degree of branching and crude lamellae. Measurements of the skull revealed characteristic differences among the brachycephalic dog breeds. The pug had an even shorter craniofacial skull than the French and English Bulldogs.

The severe intranasal deformities in brachycephalic dogs described here for the first time are the basis for a new pathophysiologic understanding of BAS.

Detailed structural analysis of aberrant, stenosing conchae (RAC, CAC) is an indispensable prerequisite for the development of an intranasal surgical therapy of BAS in the form of partial laser-assisted turbinectomy (LATE therapy).