Mix all ingredients well in a large bowl until a soft dough forms.
Roll into 1" balls and press down with a fork (creating a criss-cross pattern) or pat to about 1" thickness and cut with a cookie cutter to desired shape.
Place on a parchment lined cookie sheet and bake 20-25 minutes.
They won't expand, so you can place them close together.
Remove from oven and let cool.
Store in an airtight container in the refrigerator.
Notes
Make sure you have a can of pureed pumpkin and not a can of pumpkin pie mix. The latter has added sugars and flavorings.
Instead of rolling the dough into balls, roll it to a 1" thickness on a lightly floured surface. Then, cut it into dog-themed shapes using fun cookie cutters.
Don't worry about overcrowding the cookie sheet. The treats won't expand, so you can arrange them side-by-side on the cookie sheet.
For a firm but chewy dog treat, bake for less time -and for a hard, crunchy dog biscuit, bake the biscuits a few minutes longer.