Suggest me a 150-200 pages book from a British/American author that doesn’t feature humans as main characters

My request is a bit difficult to explain, but I'll try my best. I typically don't like books which focus on "human" kind of problems. I'm talking romance, parent-child issues, politics, yada yada. I prefer animal protagonists that are still largely animalistic or, if sentient, have "animal" problems (think Black Beauty or White Fang). I [...]