Formal:
* Canid (scientific term for the family of animals that includes dogs, wolves, foxes, etc.)
* Dog (most common and straightforward)
Informal:
* Doggo (internet slang)
* Pup (young dog)
* Hound (hunting dog)
* Fido (generic name for a dog)
Literary:
* Wolfish (referring to wolf-like traits)
* Cur (archaic term for a dog, often used negatively)
* Shepherd (for a herding dog)
* Spaniel (for a dog breed)
The best alternative depends on the context and desired tone.