Fig 1.
Craniometric measuring points on the skull of a Domestic shorthair cat.
Three-dimensional reconstructions of a Domestic shorthair cat with a low grade of brachycephaly in a frontolateral view (A) and lateral view (B) demonstrating the craniometric landmarks. Linear measurements were obtained between the craniometric landmarks.
Fig 2.
Measurement of the craniofacial angle.
Two-dimensional CT images in a sagittal plane of a Domestic shorthair cat (A) and Persian cats with different cranial indices (B–D). The craniofacial angle is determined between the facial axis and the basilar axis. In Fig 2B–2D, the craniofacial angle (cfa) cannot be measured because the two axes diverge.
Fig 3.
Measurement of the extra-orbital parts of the eye globes.
Two-dimensional CT images in a transversal plane of a Domestic shorthair cat (A) and a Persian cat (B) demonstrating the segmentation of the intra-orbital and extra-orbital parts of the bulbi oculi: yellow = extra-orbital part of the right eye; green = intra-orbital part of the right eye; red = intra-orbital part of the left eye; blue = extra-orbital part of the left eye.
Fig 4.
Measurements of the relative height of the bony nasal aperture.
Three-dimensional reconstructions of a Domestic shorthair cat in a lateral view. The distance from the akronasion to the midpoint of the palatine process of the incisive bone compared with the distance from the prosthion to that point in the same plane to determine the relative height of the bony nasal aperture.
Fig 5.
Measurement of nasal airway passage in a Domestic shorthair cat.
Two-dimensional CT images in a transversal plane of the nasal cavity in a Domestic shorthair cat with segmentation of the airway passages and the surrounding tissues.
Fig 6.
Measurement of the nasal airway passages in a Persian cat.
Two-dimensional CT images in a transversal plane of the nasal cavity in a Persian cat with segmentation of the airway passages and the surrounding tissues.
Fig 7.
Measurement of the angle between the canine tooth and the hard palate.
Two-dimensional CT images in a sagittal plane of an less severebrachycephalic Persian (A) and an extreme brachycephalic Persian (B) demonstrating the measurement of the angle between the canine tooth and hard palate. Axis (1) passes through the dental root and the dental crown. Axis (2) runs along the most cranial and caudal points of the hard palate. Both axes are coloured yellow. Ventrally, between the two axes, the angle is measured in degrees.
Fig 8.
Measurement of dental malalignment in the maxilla and mandibula.
Three-dimensional reconstructions of the skull and teeth in a Domestic shorthair cat (A) and a Persian cat (B). The mandibula is removed from the model to assess the maxilla. Auxiliary lines (yellow) through the main tubercles of the second and third premolars of the upper and lower jaws were set, which represent the main axis of the alveolar spaces. If one or more tubercles of the following premolars were positioned laterally to the auxiliary line, the position of the tooth was considered incorrect.
Table 1.
Summary of the comparison of the craniometric indices between the Persian and Domestic shorthair cats.
Fig 9.
Comparison of craniometric properties between Persian and DSH cats.
Graphic representation of the facial index, the cranial index, the skull index and the craniofacial angle, comparing Persian and DSH cats. The values of the individual cats, the mean values, the standard deviations and the significance level are indicated.
Fig 10.
Comparison of the extra-orbital parts of the eye globes between Persian and DSH cats.
Graphic representation of the extra-orbital parts of the right and left eye globes, comparing Persian and DSH cats. The values of the individual cats, the mean values, the standard deviations and the significance level are indicated. * = p < 0.01; ** = p < 0.001 *** = p < 0.0001.
Fig 11.
Correlation of measured craniometric parameters with extra-orbital parts of the eyes.
Graphic representation of the craniofacial angle, facial index, cranial index, skull index and in correlation with extra-orbital parts of the right eye globes within the Persian cat population (linear regression analysis). The red line represents the regression line. *** = p < 0.0001.
Fig 12.
Reconstruction of the extra-orbital part of the eye globes of a Domestic shorthair cat.
Three-dimensional skull reconstructions of a Domestic shorthair cat. The different parts of the eye globes are marked in different colours: yellow = intra-orbital part of the right eye; green = extra-orbital part of the right eye; red = intra-orbital part of the left eye; blue = extra-orbital part of the left eye.
Fig 13.
Reconstruction of the extra-orbital part of the eye globes in a Persian cat.
Three-dimensional reconstructions of an extreme brachycephalic Persian in the right column. The different parts of the eye globes are marked in different colours: yellow = intra-orbital part of the right eye; green = extra-orbital part of the right eye; red = intra-orbital part of the left eye; blue = extra-orbital part of the left eye. The extremely exposed position of the bulbi in the Persian is evident.
Fig 14.
Comparison of the relative height of the naso-osseal aperture between Persians and DSHs.
Graphic representation of the relative height of the naso-osseal aperture, comparing Persian and DSH cats. The values of the individual cats, the mean values, the standard deviations and the significance level are indicated. *** = p < 0.0001.
Fig 15.
Comparison of the relative airway passages in different cross-sections between Persian and DSH cats.
Comparison of the relative nasal airways between Persian and DSH cats at the level of different cross-sections. The values of the individual cats, the mean values, the standard deviations and the significance level are indicated * = p < 0.01; ** = p < 0.001 *** = p < 0.0001.
Table 2.
Summary of the area comparison of the nasal airways of Persian and Domestic shorthair cats.
Area 1/7: area of the nares in relation to area of the meatus nasopharyngeus; area 2: upper canine; area 3: palatine fissure; area 4: bony nasal aperture; area 5: second premolar; area 6: third premolar.
Fig 16.
Comparison of the maximum angle between the canine tooth and the hard palate between Persian and Domestic shorthair cats.
Graphic representation of the maximum angle between the canine tooth and the hard palate, comparing between Persian and DSH cats. The values of the individual cats, the mean values, the standard deviations and the significance level are indicated. *** = p < 0.0001.