Originally Posted by
Absolute
If you're talking in general at an airport, several have it - such as C/D at IAD. Look for a Pet Relief sign, and there is a room with fake grass and a fire hydrant in it, on the main concourse.
Of course many airports have Pet Relief areas, as does IAH, but they are not in the area the OP feels necessary. ...just after getting off an International flight and prior to Immigration and Customs.