Investigation of a dog's brain activity related to their outstanding olfactory capabilities has been a topic of interest among researchers. For this specific study, we identified three areas of the brain that have been shown in previous studies to be relevant during the process of smell discrimination in dogs: the olfactory bulb, hippocampus, and amygdala. We set up a detection structure system based on laser and a camera to capture speckle patterns on the three regions in four dog breeds for smell stimuli: garlic, menthol, alcohol, and marijuana. The results were analyzed using an XGBoost model. Our analysis revealed that the amygdala plays a crucial role in scent differentiation. Our work offers insight into leveraging the features that characterize distinct scents in the canine brain, paving the way for developing a compact device that can interpret and translate a dog's olfactory perceptions for human understanding.