a few that come to mind
anthropomorphizing an animal, treating it like a person
treating it like a member of the family
being fooled and showering Love upon it
making decisions such as how to utilize your precious time, taking the animal into consideration
dealing with the Halachic pitfalls
giving the animal your food, buying its food, spending money on it, sometimes a great amount for health issues, when perhaps it should go to a Jew instead.
spending time caring for it