Long-term, stable access to brain function across scales enables the understanding of how brain organization evolves during development or aging. In large-brained animals, fMRI serves as a standard imaging option, albeit limited in its compatibility with other modalities that could probe activity at finer spatial and temporal scales. Functional ultrasound imaging (fUSI) offers ~150 µm spatial and up to 10 Hz temporal resolution. The cranial window required for fUSI allows other brain access modalities, e.g. Neuropixels probe or optogenetics. However, the development of multimodal brain access methods is impeded by the low availability of large-brained species. Thus, a longitudinal experimental design is essential to mitigate the constraint of low animal availability. Results: We show the viability of our new long-term fUSI method developed for monitoring activity upon natural or artificial optogenetic stimulation in deep-cortical areas in a large-brained animal species, cats. We evaluate several anesthesia protocols for their compatibility with fUSI, and assess data reproducibility, variability, and overall stability over several months. Conclusion: Our findings indicate that mesoscale access to large brains is feasible in longitudinal anesthetized experiments, with durations of at least one year. Long-term multimodal access to neuronal activity in large brains may become an indispensable component in translational neuroscience studies.