It is rare to find infected animals in the United States.

CNN: Ten things you need to know about anthrax

Toxoplasma gondii infection in humans and animals in the United States.

FORBES: House Cats Said to Lead to Car Crashes, Suicides, and Mental Disorders

Bats are one of the most common animals that transmit rabies in the United States, along with raccoons, skunks, foxes and coyotes.

CNN: Are rabies shots needed for any bat exposure?

Studies in Australia, Brazil and the United States suggest that animals in half or more of farms in many parts of those countries are infested with drug-resistant worms.

ECONOMIST: Parasitology: The risks of global worming | The

The list of sponsors included some of the biggest names in animal rights activism: the Humane Society of the United States, People for the Ethical Treatment of Animals, Farm Sanctuary and Physicians Committee for Responsible Medicine.

CNN: Vegan couture: Faux meets fabulous

As part of United's PetSafe program, employees must complete training on handling animals, the airline provides tracking information for customers, and transport vans are climate-controlled.

CNN: STORY HIGHLIGHTS

All of the animals featured in Puppy Bowl IX were provided by PetFinder.com rescue groups and shelters across the United States and Puerto Rico, and have all been adopted.

FORBES: Puppy Bowl IX Draws Record 12.4 Million Viewers, Thanks in Part to Super Bowl Blackout

Hawks, foxes and other animals need them as food, says Lindsey Sterling Crank, executive director of the Humane Society of the United States' Prairie Dog Coalition.

WSJ: In Utah, a Town Digs Deep to Battle Prairie Dogs

In the United States, a few people have developed anthrax while making traditional African drums from the skins of infected animals.

CNN: Anthrax

"We have animals trickling in very slowly, " said Rowdy Shaw, a senior field responder on the Humane Society of the United States' animal rescue team.

CNN: Wildlife rush for high ground in flood areas