Dog ownership is bad for the environment in two ways. The main way dog ownership is bad for the environment is because most dogs eat meat, and scientists from organizations as diverse as the University of California at Los Angeles (UCLA) and New Scientist magazine have proved that the carbon emitted to manufacture and distribute the food eaten by an average sized dog, like a retriever, in a year, is greater than the carbon emitted by a mid sized SUV. Owning a large dog, like a great dane or german shepherd, is even worse than owning an SUV. Here's a (long) article from the Guardian that explains more:

https://www.theguardian.com/environm...rbon-emissions

A secondary problem with dog ownership is that everything dogs eat comes out the other end, and the volume of fecal matter released by America's dogs is greater than the volume of trash generated by everyone in the state of Massachusetts.

Although the manufacture of cat food emits less carbon, because cats are smaller than most dogs, much cat food is made from fish, which contributes to the depletion of fish populations in the ocean. The most serious problem with cat ownership, though, is that scientists say cats kill 2.4 Billion (yes, Billion!) birds a year in the USA.

Although dogs and cats provide us a lot of happiness, owning one DOES have serious environmental consequences.