Brachycephalic feline noses: CT and anatomical study of the relationship between head conformation and the nasolacrimal drainage system.
OBJECTIVE
A study was designed to evaluate the influence of head conformation on the course of the nasolacrimal drainage system (NDS) in 31 brachycephalic and 15 mesocephalic cats using computed tomography (CT), CT-dacryocystography and anatomical methods.


RESULTS
The higher the degree of brachycephalia, the more the facial bones and upper canine teeth are displaced dorsally (ie, the more pronounced the dorsorotation). Dorsorotation leads to abnormal dislocation of the ventral nasal concha and to almost horizontally rotated upper canine teeth, and thus a steeply oriented NDS. In severe brachycephalia the NDS is forced to pass below the canine tooth (adopt a V-shaped course) and the drainage function seems to be inefficient.


BACKGROUND
The rotation of the upper canine teeth appears to provide a basis for classification of brachycephalia in cats. The authors recommend that breeders avoid breeding from individuals affected by this condition and to give preference to cats with longer facial bones.
Schlueter
Claudia
C
Department of Small Animal Medicine, Veterinary Faculty, University of Leipzig, Germany. schlueter@kleintierklinik.uni-leipzig.de
Budras
Klaus D
KD
Ludewig
Eberhard
E
Mayrhofer
Elisabeth
E
Koenig
Horst E
HE
Walter
Alice
A
Oechtering
Gerhard U
GU
D000818:Animals; D001947:Breeding; D002371:Cat Diseases / Q000145:classification / Q000000981:diagnostic imaging*; D002415:Cats / Q000033:anatomy & histology*; D002508:Cephalometry; D016319:Corrosion Casting / Q000662:veterinary; D019465:Craniofacial Abnormalities / Q000145:classification / Q000000981:diagnostic imaging / Q000662:veterinary*; D005260:Female; D007765:Lacrimal Apparatus / Q000002:abnormalities / Q000033:anatomy & histology / Q000503:physiopathology; D008297:Male; D008953:Models, Anatomic; D009301:Nasolacrimal Duct / Q000002:abnormalities / Q000033:anatomy & histology* / Q000503:physiopathology; D012886:Skull / Q000002:abnormalities / Q000033:anatomy & histology; D014057:Tomography, X-Ray Computed / Q000662:veterinary*