Clinical signs and magnetic resonance imaging findings of a caudal cerebellar artery infarct are reported for the first time in a dog. Clinical signs were characterised by a peracute, non-progressive, right-sided central vestibular syndrome with paradoxical right-sided head tilt. Magnetic resonance images were consistent with a territorial, non-haemorrhagic, ischaemic lesion affecting the caudo-ventral part of the right cerebellar hemisphere, mainly involving the right paramedian lobe, the ansiform lobe and the caudal cerebellar peduncle. Bloodwork results were suggestive of an underlying hypercoagulable state, although the concomitant presence of a histologically confirmed mammary gland adenocarcinoma could have also been related to the cerebellar vascular obstruction through metastatic emboli formation. Posterior-inferior cerebellar artery infarction is the human equivalent of caudal cerebellar artery infarct in dogs. © 2009 British Small Animal Veterinary Association.