Buddhist behaviour towards and thinking about animals is not always positive.
The doctrine of karma implies that souls are reborn as animals because of past misdeeds. Being reborn as an animal is a serious spiritual setback.
Because non-human animals can't engage in conscious acts of self-improvement they can't improve their karmic status, and their souls must continue to be reborn as animals until their bad karma is exhausted. Only when they are reborn as human beings can they resume the quest for nirvana.
This bad karma, and the animal's inability to do much to improve it, led Buddhists in the past to think that non-human animals were inferior to human beings and so were entitled to fewer rights than human beings.
Early Buddhists (but not the Buddha himself) used the idea that animals were spiritually inferior as a justification for the exploitation and mistreatment of animals.