If you leave a dead dog lying on the ground, it will start to decompose within a couple of hours after death. The moment the body stops pumping blood and becomes cold, decomposition begins. Within 3 to 6 hours, the body enters a stage called rigor mortis. In this phase, the part of the body that touches the ground starts to become puffy. This is because blood pooling there creates pressure and pushes bodily fluid out through the head, tummy, or back.
In addition to this, flies will begin to settle on the carcass and lay eggs. If you have a lot of scavengers in your area, they will also be attracted to the corpse. The flies will feed on the flesh and break down its cells, which produces an unpleasant odor.
You have probably seen roadkill that has a bloated appearance, and it is the result of gasses accumulating in the body. As the bloat continues, you will notice that your dog’s body looks swollen and will smell foul.
It will take up to 6 months for a dead dog to fully decompose in a temperate climate. However, this timeframe can vary significantly based on the conditions in which your dog is buried. How deep the body is buried, whether it is wrapped, or if it is placed in a coffin will impact how long it takes for the dog to reach skeleton stage. If the dog is buried without any blanket covering, in a carton box, or not at all, it could take up to 18 years for the body to become bones.