There is a short essay by George Orwell entitled "The Hanging" that I had my English 101 class read. Then they were to analyze a character. One student wanted to write about the dog because "he is the only descent character in the story." The student was certainly correct, and I'm sure the irony did not escape Orwell in having the only "beast" in the story show compassion while the humans acted like "beasts."
I've found that animals can make great characters in romance novels. In my book Abbey's Tale, the black lab Bailey helps with sea rescues, amuses students at the school for the blind, and saves
Abbey from a purse snatcher. I put Bailey in the book on a whim, and he quickly grew into a likeable character. I can't even imagine the book without him. When he gets stabbed, I'm sure the readers
long for his recovery.
Other writers have created similar roles for animals: horses,
cats, rabbits, etc. One romance writer in Dangerous Moonlight created a hero with a cat and a heroine with a large dog. The mayhem that results when those two get together is both humorous and amusing.
Don't hesitate to put animals in your stories but only ones that you know well or can research accurately for verisimilitude. Here's to furry friends!