The aim of the retrospective study was to describe the brain biopsy procedure using a new frameless optical neuronavigation system and to report diagnostic yield and complications associated with the procedure. Materials and MethOds:The medical records for all dogs with forebrain lesions that underwent brain biopsy with a frameless optical neuronavigation system in a single referral hospital between 2013 and 2020 were retrospectively analysed. Following data were collected: signalment, neurological signs, diagnostic findings, number of brain biopsy samples, sampled region, complications, duration of hospitalisation, whether the samples were diagnostic and histopathological diagnoses. The device consists of a computer workstation with navigation software, an infrared camera, patient tracker and reflective instruments. The biopsy needle was equipped with reflective spheres, so the surgeon could see the position of the needle during sampling the intracranial lesion free handed through a mini-burr hole.results: Ten dogs were included. Absolute diagnostic yield based on specific histopathological diagnosis was 73.9%. Three dogs had immune-mediated necrotizing encephalitis, two dogs showed a necrotizing leukoencephalitis and two dogs a meningoencephalitis of unknown origin. In two dogs, the brain specimen showed unspecific changes. In one dog, the samples were non-diagnostic. Seven dogs showed no neurological deterioration, one dog mild temporary ataxia and two dogs died within 36 hours post brain biopsy. clinical significance: In these 10 dogs, the frameless optical neuronavigation system employed was useful to gain diagnostic brain biopsy samples. Considering the mortality rate observed, further studies are needed to confirm the safety of this procedure and prove its actual clinical effectiveness.

A 10-month-old male Saarloos Wolfdog was presented with a history of multiple neurologic deficits that had acutely progressed. Neurologic examination findings localized signs to the cerebrum and brainstem. Magnetic resonance imaging revealed markedly enlarged and gas-filled lateral ventricles with a mass effect leading to cerebellar herniation. A right-sided defect of the cribriform plate with a dysplastic ethmoturbinate was identified as the inlet of air and origin of the intraventricular tension pneumocephalus.

Background Investigation of the MRI characteristics of the palatine tonsil in brachycephalic dogs in 3T high‐field system. Methods Eighty‐five brachycephalic dogs and 37 normocephalic dogs were divided into five groups: group 1 French bulldogs (FBs) with neurological clinical signs (n = 37), group 2 FBs with brachycephalic obstructive airway syndrome (BOAS) (n = 22), group 3 pugs with neurological clinical signs (n = 17), group 4 pugs with BOAS (n = 9) and group 5 normocephalic dogs (n = 37). Cross‐sectional area and volume measurements were performed, and tonsillar margination and contour, shape, signal intensity and homogeneity/heterogeneity of the palatine tonsils were evaluated and compared. Results Cross‐sectional area and volume measurements of the tonsils showed no significant differences between brachycephalic and normocephalic dogs with the exception of the dogs of group 2 (FB BOAS), which showed relatively high volume and large cross‐sectional area in comparison to other groups. In 87% of the brachycephalic animals, the tonsils were well defined. A smooth contour was detectable in 91.8% and a rounded shape in 94.7% of brachycephalic dogs. Signal intensity was assessed as hyperintense in relation to the musculature and iso‐ to hyperintense to the soft palate. Heterogeneous appearance was described in 86.9% of the brachycephalic animals. Conclusions The MRI characteristics of the tonsils of brachycephalic dogs do not differ considerably from those of normocephalic dogs. In FBs with distinct clinical signs of obstructive airway syndrome, increase in cross‐sectional area and volume of the tonsils was detected.