When it comes to animal suffering in the United States, farm animals are in a category of their own.

True, hundreds of thousands of dogs and cats are euthanized each year in shelters. Plenty of other animals are killed to produce clothing or are used in lab tests, circuses or theme parks.

But all of them combined don't add up to even a half percent of the animals killed for food each year.

This vast disparity is not reflected in how Americans spend their charity dollars. Quite the opposite.

Americans give well over $1 billion to animal welfare groups each year. Only a tiny sliver of that money, about four-fifths of 1 percent, goes to nonprofits devoted to protecting factory-farmed animals.