Why Do Dogs Roll In The Grass?

Is it just a back scratch?

Often, yes. Dogs can't easily scratch the middle of their back, and rolling on grass gives them a full-body scratch that reaches all the spots they can't get to with their paws. The texture of grass, especially cool, slightly damp grass, feels great on their skin. If your dog rolls after a bath, they may also be trying to get rid of the shampoo scent and replace it with something that smells more natural to them. Dogs generally prefer their own smell (or the smell of their environment) over whatever floral shampoo you just used.

Why do they roll in poop and dead things?

This goes back to scent masking, the same instinct that drives wolves to roll in strong odors to disguise their own scent during hunts. Your dog is coating themselves in a powerful smell that overrides their personal scent signature. Whether it's a dead worm, goose poop, or something even worse, the drive is the same: cover up your own smell with something stronger. It's been observed in wolves and wild canids extensively, and domestic dogs haven't let go of the instinct just because they live indoors now.

Could they be trying to tell other dogs something?

Some behaviorists believe rolling in strong scents also serves a communication function. Wolves have been observed rolling in novel scents and then returning to the pack, where other pack members sniff them intensely. The theory is that the scent-covered wolf is essentially reporting back about what it found. Your dog may be doing a version of the same thing: carrying an interesting scent home to "show" you or the other pets in the house.

Should I stop it?

Rolling in clean grass is completely harmless and genuinely enjoyable for your dog. Let them have it. Rolling in poop, dead animals, or chemically treated lawns is worth preventing. A solid recall command and keeping your dog on a leash in areas where gross stuff is likely to be found are your best tools. If your dog does get into something, an enzymatic pet shampoo works better than regular soap for cutting through the really foul stuff.