Although dogs have never been demonstrated to be sources of
infection for humans, they can become infected with Y. pestis
and develop antibodies to this bacterium.
Occasionally dogs exhibit clinical signs of illness, including lesions that could pose a risk of contagion.
Probably the greatest plague-related threat posed by dogs
is that they will transport Y. pestis-infected fleas
or rodent or rabbit carcasses into residential environments.
Y. pestis infections are rarely identified in ungulates
(animals with hooves) in the United States, and these animals
probably pose relatively little risk to humans.
Any ungulate, however, that becomes seriously ill or dies under suspicious circumstances following an intentional release of plague should be examined to determine whether it was infected with Y. pestis.