As there are nerve cells in stomach linings, one would assume so. Schwann cells are glial cells that protect and help neurons and are found in the peripheral nervous system--all nerves outside the brain and spine. So although I've never studied a dogs stomach, it seems impossible for them not to have them. Axons need the insulation provided by the schwann cells to properly function.
Schwann cells and oligodendrocytes
This questions has been answered below in the related discussions, "what are Schwann cells"
Schwann cells are glia that myelinate the neurons of the Peripheral Nervous System
The Remaining Schwann Cells schwann cells, after injury and disruption to target, the remaining schwann cells undergo a rapid mitotic division until the target tissue is reached and the successful pathway is regenerated under the structural guidance of the schwann cells,
Schliden, Schwann, and Virchow.
They are called oligodendrocytes but in the peripheral nervous system you would call them schwann cells.
Theodor Schwann concluded that all animal tissues were made of cells.
neurons
His conclusion was that all animals have cells.
schwann cells
oligodendrocytes
Schwann cells