Brock appears 63 times at rank 1623 on male pets. It's a one-syllable Old English name that started as a word for badger before becoming a surname and eventually a given name, which gives it an unexpected animal-naming heritage that most owners probably don't know about but would appreciate.
The Name That Already Means Animal
Brock derives from the Old English word brocc, meaning badger, which makes it one of the rare human names with a direct animal-world etymology. Naming a dog Brock is, technically, naming a dog "Badger" in a language few people still recognize. The human name is at /names/brock.
The Pokémon Connection
Brock from Pokémon, stoic and reliable, is the other cultural anchor for anyone who grew up watching the anime. The character's steadiness makes the name an easy fit for large, dependable breeds: Rottweilers, Mastiffs, Great Danes. One syllable, strong consonants, projects well at training distance.
The Counter-Reading
Brock is masculine without being aggressive, simple without being plain. The badger etymology is a genuine plus for owners who dig into it. The name's only real limitation is that it's firmly gendered. For the right dog, it's a strong, underused choice.