Portmanteau of animal and weaboo
(or more accurately wolfaboo
A special breed of animal lover who, unlike the standard view of animal lovers as kind and caring individuals who extend their compassion to all sentient beings, is so sentimentally obsessed with animals to the point where they become utterly illogical, insane and vicious.
Animalaboos have little to no understanding of nature, science or anything logical about animals, and instead get their impression from an anthropomorphized Bambi-esque viewpoint. To them, animals are nothing but pure, harmless angels who can do nothing but act peaceful and caring 24/7, and if they show anything that isn't they blame humans. In any conflict involving humans and animals, to the animalaboos, the animals always win.
While many animal lovers expand their compassion to include all animals as well as humans, animalaboos reserve all their compassion to animals (notably cute or beautiful ones) and show hostility to humans.
Opposing animal cruelty, being vegetarian/vegan, advocating humane treatment of animals or caring about animals and humans equally does NOT make someone an animalaboo. Even most animal lovers, vegans and animal rights activists (yes, even big PETA activists) facepalm at the behaviour of animalaboos, who are seldom vegan. While obviously there are very few people who match the behaviour of an animalaboo exactly, a significant proportion of internet community tends to exhibit high degrees of animalaboo-ism.
Comparison of standard animal lovers and animalaboos.
Example 1 - Wolves hunt deer for food.
Standard animal lover: "As cruel as it may look, it is nature."
Animalaboo: "FUCKING MONSTER WHY DIDN'T THEY HELP THE DEER I HOPE THE CAMERAMEN DIE IN A FIRE"
Example 2 - Pro-animal terrorist poisons scientists at cosmetic research lab
Standard animal lover: "While I think cosmetic animal testing is cruel, what that guy did was evil. Shame on him."
Animalaboo: "What a hero! Killing evil humans to save the lives of innocent pure animals. How dare anyone bash him when he cares about animals!"
Example 3 - Aid for victims of major disaster in (foreign country).
Standard animal lover: "My heart goes out to all the people and animals affected by this disaster. I hope to lend a hand to the people affected by the disaster as well as the animals."
Animalaboo: "HAW HAW (racist slur) GOT WHAT THEY DESERVE FOR EATING DOGS LET'S KILL THEM ALL AND FEED THEIR BODIES TO THE ANIMALS."
Example 4 - Terrorist use hungry dogs to eat a hostage alive.
Standard animal lover: "This is cruelty to the hostage and the dog, especially the hostage."
Animalaboo: "Yaay dogs finally got a meal happy ending AND I HOPE WHOEVER MADE THOSE DOGS HUNGRY DIES A SLOW PAINFUL DEATH!!!!!"
Example 5 - Dog owner using a low-budget leash
Standard animal lover: "I love your dog. I recommend (better leash) for your dog."
Animalaboo: "You dare give your dog anything but luxury? ANIMAL ABUSER BURN IN HELL!!!"