Not the main dog, but there are multiple dogs that still are killed throughout the book. Sometimes by other dogs, and once, several dogs fall through ice and drown.
There is one part in which the main dog gets beaten with a stick. In another, one of his friends gets devoured by wolves, though I don't think this would count as abuse.
The canine protagonist is forced into a life in a dog fighting ring, the fights are pretty awful but well written. The author wrote this book to very intentionally villify the practice and it was instrumental in raising awareness to successfully get dog fights banned in the US and Canada.
no, but the last owner is killed by alaskan natives which can be considered stereotypical?? idk if thats the right word. but it sets in the "savage" stereotype that a lot of people use against natives.
This is kind of ambiguous. The dog goes free and gets to run around in the wild with a wolf pack, but it's heavily implied that his last owner, who actually took good care of him, was killed, so... do with that what you will.