Real-life issue: Rabies
Rabies is a virus that can affect the nervous system of animals and is often transmitted through bite wounds. The disease is discussed several times in Old Yeller, and is regarded as a growing plague in their community. At the time, it would have been necessary to kill Old Yeller because a rabid animal could infect an entire farm.
Since the creation of the first rabies vaccine in 1885, humans could have themselves and their animal companions vaccinated as a preventive measure. While humans can acquire rabies vaccines before and after infection, animals often pass away once infected by rabies. According to the World Health Organization, the Philippines is one of the top ten countries with a rabies problem.