Like any behavior, dogs lay on their backs for many different reasons. Context helps narrow down the options to help you understand what your dog is communicating.
- Climate Control: The fur and skin on your dog’s belly are thinner. Exposing their belly helps cool them down in hot environments. When lying on their back, their paw pads–the location for their sweat glands–are also aired out.
- Physical Comfort: Back sleeping avoids putting pressure on certain muscles and joints. Elderly or arthritic dogs prefer sleeping on their backs.
- Relaxation: Wild dogs rarely sleep on their backs, preferring to adopt more defensive sleeping postures.
- Submission: Dogs roll over to expose their bellies or genitals as a show of submission.
Friendly vs. Fearful
Dogs roll onto their backs as part of normal dog-to-dog communication. We classically interpret it as an act of submission; one dog exposes their belly to explain that they are harmless, preventing the approaching dog from acting aggressively.
However, some dogs also roll over in the middle of friendly play. Filtered through our understanding of dominant and submissive behavior, we might be tempted to label the dog lying down as “submissive” and the one standing as “dominant.”
Researchers at the University of Lethbridge and the University of South Africa beg to differ. After analyzing videos of dogs playing, Kerri Norman and colleagues concluded that size did not impact which dog was more likely to roll over. Pushing back against the narrative that the weaker or smaller dog lies down, the study–backed up by Alexandra Horowitz, the head of the Dog Cognition Lab at Barnard–observed that large dogs tended to lie down more, allowing their playmates to jump on or mouth them.
Of the 248 rolls they observed, none were submissive and were instead classified as defensive. Dogs used their positions on the ground to launch playful bites at their partners and keep engaging in play behaviors, leading Norman to conclude that dogs that roll over during play are engaging in play fighting.
When dogs do roll over in a show of submission, they’re demonstrating appeasement behaviors. They exhibit stiff or tense body language, keeping their heads turned away and avoiding eye contact. Their tail may be curled over their genitals. Some dogs submissively urinate.
Dogs may roll over submissively when approached by unfamiliar dogs or humans, then get up to greet. They have loose body language with a rapidly wagging tail and offer relaxed eye contact, and may appear to have a hard time remaining on the ground.
These dogs are social, but past negative experiences cause them to try and pre-empt potential aggression. Negative experiences can be as minor as being stroked too roughly or having a tense introduction.
Some dogs are also trained to offer their belly as a way of curbing inappropriate jumping. Always ask their handler or wait for the dog to stand and approach before touching an unfamiliar dog.
You may have noticed that your dog likes to lie belly up in the sun, with no dogs or humans around to trigger submissive or playful behavior. Like cats, dogs enjoy sunbathing and will select a warm spot to stretch out in. Because the fur on their stomachs is thinner, it is possible for dogs to get sunburned, but the behavior only indicates that your dog is relaxed and comfortable.
Dogs may also lie on their backs and wiggle around to scratch an itch. Textured surfaces such as carpets make for excellent back scratchers. Some dogs also lie on their toys to itch at hard-to-reach spots.