You can set out free (medicated) food for the wildlife. That will treat the vast majority of them.
That might work for once-off vaccinations of precisely targeted animals in densely populated areas but not delivering periodic high doses of medication to treat parasites to animals across 100s of millions of acres.
That might work for once-off vaccinations of precisely targeted animals in densely populated areas but not delivering periodic high doses of medication to treat parasites to animals across 100s of millions of acres.