Objective—To determine the effect of head conformation (brachycephalic, mesaticephalic, and dolichocephalic) on olfactory bulb angle and orientation in dogs by use of in vivo MRI.
Animals—40 client-owned dogs undergoing MRI for diagnosis of conditions that did not affect skull conformation or olfactory bulb anatomy.
Procedures—For each dog, 2 head conformation indices were calculated. Olfactory bulb angle and an index of olfactory bulb orientation relative to the rest of the CNS were determined by use of measurements obtained from sagittal T2-weighted MRI images.
Results—A significant negative correlation was found between olfactory bulb angle and values of both head conformation indices. Ventral orientation of olfactory bulbs was significantly correlated with high head conformation index values (ie, brachycephalic head conformation).
Conclusions and Clinical Relevance—Low olfactory bulb angles and ventral olfactory bulb orientations were associated with brachycephalia. Positioning of the olfactory bulbs, cribriform plate, and ethmoid turbinates was related. Indices of olfactory bulb angle and orientation may be useful for identification of dogs with extremely brachycephalic head conformations. Such information may be used by breeders to reduce the incidence or severity of brachycephalic-associated diseases.
Objective—To perform morphometric analysis of the caudal cranial fossa in Cavalier King Charles Spaniels (CKCSs), to assess the relationship between caudal fossa dimensions and the frequency of magnetic resonance imaging (MRI) features of occipital abnormalities in CKCSs (with and without syringomyelia), and to compare caudal cranial fossa measurements in CKCSs with measurements of 2 groups of mesaticephalic dogs.
Animals—70 CKCSs and 80 mesaticephalic (control) dogs.
Procedures—Dogs were placed into 4 groups as follows: Labrador Retrievers (n = 40), spaniel-type dogs (40; English Springer Spaniels and Cocker Spaniels), CKCSs with syringomyelia (55), and CKCSs without syringomyelia (15). Multiple morphometric measurements (linear, angular, and area) were obtained from cranial midsagittalT2-weighted magnetic resonance images including the brain and cervical portion of the spinal cord. Several specific MRI findings were also recorded for CKCSs that appeared to affect the occipital bone and cervicomedullary junction.
Results—No significant difference was identified among breeds in control groups and between sexes in any of the groups for all morphometric measurements. Significant differences were identified in CKCSs, compared with mesaticephalic dogs, in the area of the caudal cranial fossa and for several linear measurements that reflected the length of the ventral aspect of the occipital bone. These differences were greater in CKCSs with syringomyelia. All CKCSs had abnormalities in occipital bone shape.
Conclusions and Clinical Relevance—CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia.
Objective—To determine radiographic, magnetic resonance
imaging (MRI), computed tomography (CT),
and rhinoscopic features of nasal aspergillosis in
Animals—15 client-owned dogs.
Procedure—All dogs had clinical signs of chronic
nasal disease; the diagnosis of nasal aspergillosis was
made on the basis of positive results for at least 2
diagnostic tests (serology, cytology, histology, or fungal
culture) and detection of typical intrasinusal and
intranasal fungal colonies and turbinate destruction
via rhinoscopy. Radiography, MRI, and CT were performed
under general anesthesia. Rhinoscopy was
repeated to evaluate lesions and initiate treatment.
Findings of radiography, MRI, CT, and rhinoscopy
Results—MRI and CT revealed lesions suggestive of
nasal aspergillosis more frequently than did radiography.
Computed tomography was the best technique for
detection of cortical bone lesions; the nature of abnormal
soft tissue, however, could not be identified.
Magnetic resonance imaging allowed evaluation of
lesions of the frontal bone and was especially useful for
differentiating between a thickened mucosa and secretions
or fungal colonies; however, fungal colonies could
not be differentiated from secretions. Rhinoscopy
allowed identification of the nature of intranasal and
intrasinusal soft tissue but was not as useful as CT and
MRI for defining the extent of lesions and provided no
information regarding bone lesions.
Conclusions and Clinical Relevance—The value of
CT and MRI for diagnosis of nasal aspergillosis was
similar and greater than that of radiography.
Rhinoscopy is necessary because it is the only technique
that allows direct visualization of fungal
colonies. (J Am Vet Med Assoc 2004;225:1703–1712)