Companion animals have been known to contract flu from other species — canine influenza (H3N8) originated in horses, and cats contract avian influenza (H5N1) from eating birds. But this appears to be the first time a cat has contracted influenza from a human. Two pet ferrets, one in Oregon and one in Nebraska, have also tested positive for H1N1, and the virus has also been transmitted between humans and pigs.
http://well.blogs.nytimes.com/2009/11/05/the-cat-who-got-swine-flu/
http://www.google.com/hostednews/ap/article/ALeqM5jPhJ3QpRycpDLrrOUwe7f4yZ5BSQD9CFBB6O0
http://archives.chicagotribune.com/2009/nov/08/business/chi-flu-pets_mullennov08