No one knows for certain why a dog would rather be alone when he needs to vomit, instead of having you rub his back and tell him everything's going to be alright.
"Many dogs do like to retreat to a private place when they vomit, and some even try to bury the vomit under dirt when outside or with household items that are laying around when inside," Jodi Thompson, a veterinarian at DoveLewis Emergency Animal Hospital, tells The Dodo.
"It could be an instinct to not show weakness, especially in front of predators," Thompson says. "It could be that the dog feels bad for making a mess and doesn't want to get into trouble. For some dogs, it could be a way to stay clean or cover up the smell."
Some experts suggest dogs may still be wired for a pack mentality, a social order established when the animals ran wild.
"That's why they appear so vulnerable and unsure when pooping," Amy Klein, who works with dogs through Marley's Mutts, tells The Dodo. "Their defenses are down. They won't make eye contact with you. They don't want to be challenged when in weaker moments."