Did Toby encounter any enemies throughout the book A Dog's Purpose?

Toby is the protagonist of A Dog's Purpose and, fittingly, a dog. He is reincarnated several times throughout the story, so he has plenty of time to gather some enemies. In his first life, he's born wild and is adopted by a woman who keeps a large number of dogs in a pen in her yard. Then he is found and put down by animal control due to the poor conditions of the pen. Animal control definitely establishes themselves as one of Toby'd enemies, and one could argue that the woman's negligence and her decision to take Toby out of the wild makes her an enemy as well.
In his next life, Toby is adopted by a truck driver who leaves him in a hot car while he goes into a bar, and he is rescued by a woman who gives him to her son, Ethan. The truck driver could be considered an enemy due to his negligence. Toby is later kidnapped by a neighborhood kid, Todd, a clear enemy who later burns down Ethan's house. A while after Ethan goes to college, Todd gets sick, and Ethan's family decides to put him down. It's for the reader to decide whether this was a kind action or positions them as Todd's enemies.
In his next life, he is owned by a cop who gets shot and forced into retirement, and Toby is then given to another cop. No clear enemies appear, unless you count his handlers for forcing him into dangerous situations.
In his next life, a man buys him to give to his girlfriend, who neglects him. He's eventually passed to the girlfriend's mother, and her boyfriend dumps him on the side of the road. Both the girlfriend and her step father could be considered enemies.
All in all, Toby lives several rough lives, but mostly he suffers from neglect more than active malice or from humans hastily deciding to buy him and then not actually wanting him for his whole life. The title of the book, A Dog's Purpose, highlights the fact that generally, humans think about what purpose dogs can serve for them, which doesn't necessarily set dogs up to live their own fulfilling lives.