Where can I get good information about the global impacts of keeping pets?

Some time ago I saw an article that correlated the global warming impact of owning a large dog as twice that of owning an SUV, due to the meat that it takes to feed a dog. More recently, with food prices beyond manageable for millions (billions?), and global food riots, I am wondering if people should start making a pledge to give up their “future” pets. They appear to be an increasingly huge extravagance. I would like DATA on the global impacts of pet-keeping.