Awww - what a wonderful story.
Checking on the veracity of the post (guess I'm just a cynic), I find four different 'hoax-buster' sites all identify that the photos are genuine but the story that accompanies the photos, is not. Sorry to burst this bubble ... I *love* the sentiment!
The photos are from a Thailand zoo, where they intermigle species as exhibits ...
http://www.snopes.com/photos/animals/tigerpig.asp
http://urbanlegends.about.com/librar...nd_piglets.htm
http://www.truthorfiction.com/rumors/t/tiger-pigs.htm
http://www.hoax-slayer.com/tiger-piglets.html