Pets - especially cats and dogs
Did you know that dogs are actually omnivores like us, and that they therefore can thrive on a vegetarion diet? My mother used to cook for the family dog, which would lap it up, including leftover pasta (without the sauce) - no questions asked.
According to PETA, "feeding companion animals commercial pet foods may be jeopardizing their health. Supermarket pet foods are often composed of ground-up parts of animals ...who fall into one of the categories of the four D’s—dead, dying, diseased, or disabled...." And that many dogs are being fed a healthy, meatless diet with "[O]ne remarkable example is that of Bramble, a border collie whose vegan diet of rice, lentils, and organic vegetables contributed to a nearly record-breaking lifespan of at least 27 years."
As the meat sector is a large contributor to climate change and environmental degradation, you might want to switch your dog to a less meat-intense diet.
If you are not keen on also cooking for your canine friend, here are a few companies, that offer vegetarian and vegan meals: Veggiepets and Lily's kitchen, or if you feel like treating your dog to a homecooked meal, here are some recipes.
Or if you don't want to go meat-free, ask your local butcher if they have any offal or rumen (stomach of a ruminant) that you can cook for your dog and mix with some (leftover) rice, which is a great way of using nutritious parts of animals, that humans rather avoid to eat.
Now to the slightly unpleseant business of cleaning up after your dog. All those small black plastic poo-bags contribute to the huge problem of plastic waste, so make sure that you only use degradable bags or use a scoop. Here are a few companies offering environmentally friendly poo-bags, with some clever names that must have taken ages to come up with like: Poobagsdirect, Mutts Butts, and Biobags. Or use some cardboard scoops, either from Poopscoop, or Kakas cardboard dog poop scoops.
The biggest problem with cats is that they are truly carnivores so you shouldn't force a vegetarian diet on them. However, buy sensical, I don't think a cat needs real shrimps in its diet, when the shrimp farming or fishing is such an environmentally degrading activity and linked to squalid labour conditions imposed on the fishermen. Cat and dog food production have high environmental costs but as for dog food, you can either cook some of the food yourself by using offal or try a more ethical cat food supplier like Lily's kitchen.
Also, always ensure that your cat wears a bell so it can't catch any wildlife.
General pet advice
It might be debatable but some argue that keeping a pet is fundamentally unethical.
But whatever your belief, inform yourself thoroughly about the animal you want to get as a pet, before you make the purchase!
If you want to share your life with an animal, make sure that you provide the right habitat for it, which doesn't just means a place to sleep and eat but it might also mean a companion so that they don't get lonely. Don't get a large dog if you live in a smal flat or buy a bird that has to sit in cage all day - you get the picture. If not, here are some more guidelines.
Avoid “exotic” animals such as tortoises, lizards, snakes and monkeys, if bought from a store, at auctions or the Internet. As PETA states on its website "... often, life in captivity rapidly leads to pain and death for these animals, who frequently suffer from malnutrition, an unnatural and uncomfortable environment, loneliness and the overwhelming stress of confinement."
Rescue an abandoned animal from one of these charities: "Save the Strays", "Bluecross", "Society for abandoned animals", "The animal house rescue", "Abandoned animal association", "Freshfields", or especially for dogs: "SPDC", "Pawprints dog rescue", "Dog watch UK", or any other association close to you.