The olfactory sense of the domestic dog is widely recognized as being highly sensitive with a diverse function; however, little is known about the structure of its olfactory system. This study examined a cohort of mixed-sex mesaticephalic canines and used diffusion tensor imaging (DTI), an MRI technique, to map connections from the olfactory bulb to other cortical regions of the brain. The results were validated using the Klingler dissection method. An extensive pathway composed of five white matter tracts connecting to the occipital lobe, cortical spinal tract, limbic system, piriform lobe, and entorhinal pathway was identified. This is the first documentation of a direct connection between the olfactory bulb and occipital lobe in any species and is a step toward further understanding how the dog integrates olfactory stimuli into their cognitive function.

SIGNIFICANCE STATEMENT The highly sensitive olfactory system of the domestic dog is largely unexplored. We applied diffusion tractography and dissection techniques to evaluate the white matter connections associated with the olfactory system in a large cohort of dogs. We discovered an extensive white matter network extending from the olfactory bulb to form novel connections directly to other cortices of the brain. This is the first documentation of these novel olfactory connections and provides new insight into how dogs integrate olfactory stimuli in their cognitive functioning.

家犬的嗅觉被广泛认为是高度敏感的，具有多种功能；然而，人们对其嗅觉系统的结构知之甚少。这项研究检查了一组混合性别的中脑犬科动物，并使用扩散张量成像 (DTI)（一种 MRI 技术）来绘制从嗅球到大脑其他皮质区域的连接图。使用 Klingler 解剖方法验证结果。确定了一条由五个白质束组成的广泛通路，这些通路连接到枕叶、皮质脊髓束、边缘系统、梨状叶和内嗅通路。

意义声明家犬的高度敏感的嗅觉系统在很大程度上是未开发的。我们应用弥散纤维束成像和解剖技术来评估与一大群狗的嗅觉系统相关的白质连接。我们发现了一个广泛的白质网络，从嗅球延伸出来，直接与大脑的其他皮质形成新的连接。这是这些新颖的嗅觉联系的第一份文件，并提供了关于狗如何将嗅觉刺激整合到其认知功能中的新见解。