Morphometric features of the craniocervical junction region in dogs with suspected Chiari-like malformation determined by combined use of magnetic resonance imaging and computed tomography.
OBJECTIVE
To objectively describe morphometric features of the craniocervical junction region of Cavalier King Charles Spaniels (CKCSs) and non-CKCS dogs with suspected Chiari-like malformation (CLM) and identify associations between these features and the presence of other malformations in this region.


METHODS
216 CKCSs and 58 non-CKCS dogs.


METHODS
Magnetic resonance and computed tomographic images of the head and craniocervical junction region of patients evaluated because of suspected CLM were assessed for cerebellar compression (CC), ventral spinal cord compression at the C1-C2 articulation (medullary kinking), and dorsal spinal cord compression at the C1-C2 articulation (dorsal compression). A compression index was calculated for each of these 3 locations in each dog. Multiple logistic regression analysis was performed to determine whether breed (CKCS vs non-CKCS) and compression index values were associated with the presence of other craniocervical junction abnormalities.


RESULTS
All 274 dogs had CC; medullary kinking was identified in 187 (68.2%) and dorsal compression was identified in 104 (38.0%). Atlantooccipital overlapping (AOO) was identified in 76 (27.7%) dogs. Breed of dog (CKCS vs non-CKCS) and value of CC index were the only significant predictors of AOO. The CKCSs had an almost 5-fold decrease in risk of AOO, compared with the non-CKCS dogs, and the risk of AOO nearly doubled for every 10% increase in CC index.


CONCLUSIONS
The anatomic abnormality responsible for CC was AOO in a substantial percentage of dogs suspected to have CLM. The CC index value may be used to help differentiate subtypes of craniocervical junction abnormalities in dogs.
Canine Chiari Institute, Long Island Veterinary Specialists, 163 S Service Rd, Plainview, NY 11803, USA. dmarino@livs.org
Dominic J
DJ
Marino
Catherine A
CA
Loughin
Curtis W
CW
Dewey
Leonard J
LJ
Marino
Joseph J
JJ
Sackman
Martin L
ML
Lesser
Meredith B
MB
Akerman
D000818:Animals; D001139:Arnold-Chiari Malformation / Q000000981:diagnostic imaging / Q000473:pathology / Q000662:veterinary*; D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging / Q000473:pathology; D054022:Cerebrum / Q000000981:diagnostic imaging / Q000473:pathology; D004283:Dog Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D004285:Dogs / Q000002:abnormalities*; D005260:Female; D016015:Logistic Models; D008279:Magnetic Resonance Imaging / Q000662:veterinary; D008297:Male; D008526:Medulla Oblongata / Q000000981:diagnostic imaging / Q000473:pathology; D009333:Neck / Q000000981:diagnostic imaging / Q000473:pathology*; D012886:Skull / Q000000981:diagnostic imaging / Q000473:pathology*; D013045:Species Specificity; D014057:Tomography, X-Ray Computed / Q000662:veterinary