Aims 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. Findings 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. Practical relevance 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.

Selective breeding for short head conformation reduces the size of the nasal cavities to such an extent that intranasal structures grow aberrantly and malformed, leading to obstructed air conducting spaces. Intranasal airway obstruction of brachycephalic dogs may contribute to their exercise and heat intolerance because of impaired pulmonary ventilation and compromised thermoregulatory functions of the canine nose. Failure to address intranasal obstruction might be an explanation for lack of therapeutic success after conventional surgery for brachycephalic syndrome. Future consideration should be given to the diagnosis, management, and treatment of this newly described aspect of airway obstruction.

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Background: Cat breeders observed a frequent occurrence of internal hydrocephalus in Persian cats with extreme brachycephalic head morphology.Objective: To investigate a possible relationship among the grade of brachycephaly, ventricular dilatation, and skull dysmorphologies in Persian cats.Animals: 92 Persian-, 10 Domestic shorthair cats. Methods: The grade of brachycephaly was determined on skull models based on CT datasets. Cranial measurements were examined with regard to a possible correlation with relative ventricular volume, and cranial capacity. Persians with high (peke-face Persians) and lower grades of brachycephaly (doll-face Persians) were investigated for the presence of skull dysmorphologies.Results: The mean cranial index of the peke-face Persians (0.97 AE 0.14) was significantly higher than the mean cranial index of doll-face Persians (0.66 AE 0.04; P < 0.001). Peke-face Persians had a lower relative nasal bone length (0.15 AE 0.04) compared to doll-face (0.29 AE 0.08; P < 0.001). The endocranial volume was significantly lower in doll-face than peke-face Persians (89.6 AE 1.27% versus 91.76 AE 2.07%; P < 0.001). The cranial index was significantly correlated with this variable (Spearman's r: 0.7; P < 0.0001). Mean ventricle: Brain ratio of the peke-face group (0.159 AE 0.14) was significantly higher compared to doll-face Persians (0.015 AE 0.01; P < 0.001).Conclusion and Clinical Relevance: High grades of brachycephaly are also associated with malformations of the calvarial and facial bones as well as dental malformations. As these dysmorphologies can affect animal welfare, the selection for extreme forms of brachycephaly in Persian cats should be reconsidered.

Radiologists are regularly faced with the task of comparing image quality obtained using different imaging systems or settings. Visual grading techniques can be used to evaluate the quality of images by grading the clarity of reproduction of anatomical or pathological structures. The methods, which include "visual grading analysis (VGA)" and the "image criteria (IC) study", are characterised by their attractive simplicity and reliability. Non-parametric rank-invariant statistical methods are suitable techniques for statistical analysis of VGA-data. Båth and Månsson (2007) introduced such a method and termed it "visual grading characteristics (VGC) analysis". This paper gives an overview of the principle together with an example of its use in veterinary radiology. The aim of this review article is to encourage veterinary researchers to apply this method which has proven valuable in the human field. Basically, the method can also be applied for the analysis of other categories of images (e.g. histological sections, cytological smears) in cases where the task is to evaluate features subjectively on the basis of a score, allowing some degree of freedom of decision. Furthermore, the aim of the investigation is not necessarily restricted to quality aspects. Other questions such as the effects of treatment options on the appearance of certain structures can be compared as well.