Specifically, a virus or bug passed to a pig is considered a huge threat in the medical community, because pigs can pass their diseases onto humans.
Pigs and goats, however, with cattle, horses, asses and dogs, have been introduced, have multiplied, and in considerable numbers run wild.
Pigs, sheep and goats are also kept in considerable numbers.
On many of the islets numerous tropical fruits are found growing wild, but they are no doubt escapes from cultivation, just as the large herds of wild cattle, horses, donkeys, pigs, goats and dogs - the last large and fierce - which occur abundantly on most of the islands have escaped from domestication.
We thus see that the American and the European-Asiatic elements of the flora are nearly equivalent; and if the flora of Arctic North America were better known, the number of plants common to America might be still more enlarged.5 In the south, a few goats, sheep, oxen and pigs have been introduced.