Lassie - Episode

Paul purchases an expensive purebred Holstein cow to expand his herd, but his plans are threatened when he tends a neighbor's cattle herd who are unknowingly carrying the contagious hoof and mouth disease. When the Animal Control officer comes to destroy both the Martin's cows to prevent the spread of the disease, Timmy and Lassie hide the cows in the woods until the incubation period is over.
TRIVIA: Hoof and mouth disease is a highly contagious viral disease that affects coven footed animals such as cattle and pigs, sheep, bison, and deer. Cattle suffering from hoof and mouth disease appear lethargic and show signs of lameness. Sores and blisters form along the gums and tongues of affected animals, making eating and drinking painful. The soft tissue between the hooves is also prone to blistering, which results in limping and reluctance to move. Infected cattle may also drool and smack their lips. Most animals survive hoof and mouth disease, although infected calves have a higher mortality rate than adult animals. There is no treatment currently available for hoof and mouth disease, thus most countries handle outbreaks by slaughtering all infected herds then either burning or burying the carcasses to prevent the disease from spreading. The areas are then disinfected to prevent transmission to healthy cattle.
While some 2nd and 3rd world countries still have incidents of the disease, the last occurring outbreak in the US occurred in 1929. Since then, the US has been free of this disease.