Due to the impact of global warming, the transition from summer to autumn in Taiwan is no longer marked solely by occasional breezes. Instead, a noticeable temperature drop occurs after the Mid-Autumn Festival. Early autumn becomes a crucial period for pet owners to pay attention to boosting the dogs' and cats' immune systems. The great temperature variation between day and night can have a particular impact on their respiratory and urinary systems. This article explores the common symptoms that cats and dogs may experience due to seasonal changes. It provides insights from a veterinarian's perspective, with the goal of assisting pet owners in enhancing their pets' immunity as they navigate the shift from autumn to winter, ensuring the well-being of their furry companions.