Magnetic resonance imaging findings in dogs with cerebral microbleeds
age-related changes, MRI, T2*, brain atrophy
Currently advances in veterinary medicine have led to a significant increase longevity of dogs, and age-related brain changes are becoming more widely recognized, such as cerebral microbleeds (CMBs), yet there are few studies describing their occurrence and epidemiology in dogs. CMBs are small focal intraparenchymal signal voids identified on T2 gradient-echo magnetic resonance imaging (MRI). The aim of this retrospective study was to describe the signalment and MRI findings in dogs with CMBs, and their association to concurrent age-related changes and other brain abnormal findings. The MRI database of a veterinary diagnostic center (CRV Imagem, Rio de Janeiro), between January 2019 and September 2020 was revised. Dogs undergoing 1.5T brain MRI with standard sequences (T2*, T2, FLAIR, T1 pre and post contrast) were included. Dogs with at least one cerebral microbleed, identified based on previous reports, were included in the CMB group; the remaining dogs were used as controls cases (group C). Signalment information as breed, age and sex, and concurrent MRI findings were retrieved from the radiology reports and compared between groups. In the CMB group, number, anatomic location (cerebral cortex, basal nuclei, thalamus, brainstem and cerebellum) and distribution of lesions (lobar and deep) were assessed. A total of 747 dogs met the inclusion criteria. Of these, 142 (19%) dogs had > 1 MHCs. Dogs with CMBs were older than control dogs (median 14 vs. 9 years) and the incidence of CMBs increased with age, especially in those older than 10 years. Small breed dogs were significantly more affected compared to large breed dogs. Most dogs had multiple CMBs (62.0%) mainly with a lobar distribution (57.7%). Brain atrophy was significantly identified concurrently with CMBs in 61.3% of dogs. In conclusion, cerebral microbleeds were a common age-related MRI finding in smaller-breed dogs, with increasing incidence in dogs older than 10 years and frequently associated to brain atrophy.