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 results of magnetic resonance
(MR) imaging in dogs with vestibular disorders
(VD) and correlate results of MR imaging with clinical
Procedure—Information on signalment, clinical signs,
and presumptive lesion location was obtained from
the medical records, and MR images were reviewed.
Results—27 dogs had peripheral VD, 37 had central VD,
and 21 had paradoxical VD. Of the 27 dogs with peripheral
VD, 11 (41%) had MR imaging abnormalities involving
the ipsilateral tympanic bulla compatible with otitis
media (6 also had abnormalities involving the petrous
portion of the ipsilateral temporal bone compatible with
otitis interna), 7 (26%) had MR imaging abnormalities
compatible with middle ear neoplasia, 2 (7%) had an ipsilateral
cerebellopontine angle lesion, and 7 (26%) did not
have MR imaging abnormalities. All dogs with central
and paradoxical VD had abnormalities evident on MR
images. Of the 37 dogs with central VD, 13 (35%) had an
extra-axial lesion, 6 (16%) had an intra-axial lesion, and
18 (49%) had multiple intra-axial lesions. In 23 (62%)
dogs with central VD, lesions on MR images corresponded
with location suspected on the basis of clinical
signs. Of the 21 dogs with paradoxical VD, 12 (57%) had
an extra-axial lesion, 5 (24%) had an intra-axial lesion,
and 4 (19%) had multiple intra-axial lesions. Location of
lesions on MR images agreed with location suspected
on the basis of clinical signs in 19 (90%) dogs.
Conclusions and Clinical Relevance—Results suggest
that MR imaging may be helpful in the diagnosis
and treatment of VD in dogs. (J Am Vet Med Assoc