Risk factors for adverse events occurring after recovery from stereotactic brain biopsy in dogs with primary intracranial neoplasia

BACKGROUND: Stereotactic brain biopsy (SBB) allows for histopathologic diagnosis of brain tumors. Adverse events (AE) occur in 5 to 29% of dogs after SBB, but risk factors associated with developing AE are poorly described. OBJECTIVE: Identify clinicopathologic, diagnostic imaging, or procedural variables that are associated with AE in dogs after SBB. ANIMALS: Twenty‐nine dogs with brain tumors. METHODS: Retrospective, case‐control study. Dogs had laboratory investigations performed before SBB, as well as clinical examinations and diagnostic imaging of the brain before and after SBB. Cases experienced AE after SBB including transient exacerbation of preexisting neurologic deficits, transient new deficits, or permanent neurologic deficits. Controls had SBB performed without AE. Fisher's exact and Student's t tests were used to examine associations between the postulated risk factors and AE. RESULTS: Adverse events occurred in 8/29 (27%) dogs, and 7/8 AE (88%) were transient. Cases were significantly more likely to have T2W‐heterogenous tumors (88 versus 38%; P = .04) and lower platelet counts (194.75 ± 108.32 versus 284.29 ± 68.54 ×10(3)/mm(3), P = .006). Dogs with gradient echo signal voids present on baseline imaging were significantly more likely to have hemorrhage present after biopsy, and 7/8 (88%) of cases had hemorrhage on imaging after SBB. CONCLUSION AND CLINICAL IMPORTANCE: Twenty‐seven percent of dogs undergoing SBB experience AE, with the majority of AE resolving with 1 week. Platelet counts should be ≥185 000/mm(3) to minimize risk of SBB‐associated AE. Observation of intracranial hemorrhage after biopsy can have important clinical implications, as this was observed in 88% of dogs with AE.