One can't treat animals' suffering separately from human problems. Attempt to set absolute priorities and solve most important tasks first is nonsensical and inhuman. If care for animals is amoral while a sigle humane on the Earth is suffering then the doctors should cure only most severe patients, teachers should teach just most backward children, and police should chase most dreadful offenders only. Not helping in an accident because there is someone in the world who suffers even more is absurdity and crime.
We notice animals' suffering around – and help them. Tasks we voluntarily and unselfish solve are mostly laborious and grievous. And we do it because we want to improve the environment a bit. The one who considers human problems more important than the problems of animals is likely to just searching for excuse and pretext to help neither animals nor people.