It might be considered the cat's revenge on the dog that chased it around the house and yard: Sometime in the late 1960s or 1970s, deadly feline parvovirus jumped from cats to dogs, becoming canine parvovirus. Then, in 1978, it started killing puppies at an alarming rate. "Most viruses go into a new host and just die out," says Laura Shackelton, a postdoc at Pennsylvania State University, who has studied the evolution of both subgroups. "This one took off."
In both species, parvovirus causes serious problems for newborns and can be fatal: Kittens develop hypoplasia, and puppies sicken with myocarditis. Older animals can suffer some effects, but they are mild and temporary. The virus can stay active in soil for long periods of time, so dogs must be vaccinated close to birth, immediately after maternal antibodies wane and before they start digging for whatever they dig for.
The carnivore parvovirus ...
