For early twentieth-century Koreans, one of the most feared invaders to breach the country’s northern border with China was the tiny viral pathogen Rinderpest morbillivirus (rinderpest, or cattle plague). This study examines the social consequences of rinderpest outbreaks along the colonial Sino-Korean border and the methods undertaken by the Japanese Government-General of Korea to control viral “invasions” from Manchuria. Rinderpest prevention primarily functioned as an extension of the colonial police. Despite universal fears of rinderpest’s ravages, which devastated a rural economy dependent on animal labor, colonized Koreans exhibited wide-ranging reactions to the heavy-handed methods adopted by imperial officials to fight the disease. Korean responses included outright resistance such as cross-border cattle smuggling, attacking veterinary officials, or protests against livestock travel bans, as well as varying degrees of cooperation. Moving chronologically from before the beginning of formal colonial rule in 1910 until the 1930s, this article strives to explain how a modern veterinary regime was implemented and negotiated in the northern colonial Korean borderland. Such a view is essential for understanding not only Korea’s colonial past but also Korean responses to infectious disease “invasions” in the present day.