Symbolism, Imagery, Allegory
Birds, dogs, pigs, rabbits, cows and horses. There sure are a lot of animals in this novel—but the ones we're concerned about most are the pigs, dogs, and rabbits.
Unless you're a vegetarian, you've probably had to justify your meat eating at some point or another. Why is it okay to kill and eat animals, but not okay to kill humans? In this novel, the answer seems to be that neither is okay but sometimes you have to do both anyway. When Santiago sees Victoria Guzmán cleaning the rabbits for dinner, he begs her to be more humane:
But she couldn't avoid a wave of fright as she remembered Santiago Nasar's horror when she pulled out the insides of a rabbit by the roots and threw the steaming guts to the dogs. "Don't be a savage," he told her. "Make believe it was a human being." (1.15)
He's kind of freaked out by the gruesome act of gutting a cute little rabbit, even though he works on the farm and probably has to do these things regularly.
The same goes for the Vicario brothers. Their job is to kill pigs every day. They're experts at it, so you would expect them not to feel any kind of guilt or pity for the animals that they slaughter. But the narrator says:
I reminded them that the Vicario brothers sacrificed the same hogs they raised, which were so familiar to them that they called them by their names. "That's true," one of them replied, "but remember that they didn't give them people's names but the names of flowers." (3.11)
Even the pig slaughterers have reservations about killing animals—imagine how they felt about killing Santiago. But even though they feel this way, the brothers continue to kill the pigs because it's their job. They have to. In the same way, they probably kill Santiago because it's their job. They have to in order to defend their family's honor.
Then, when Santiago is finally killed, he is kind of turned into an animal. The narrator says that the Vicario brothers carve him up like a pig—they even use their work tools to kill him. And just like the poor rabbits that Victoria Guzmán was cleaning earlier, the dogs howl for his guts and try to eat what's left of him after his death. No wonder Colonel Aponte became a vegetarian after the incident. It would put us off of meat for a long time too.