Preheat oven to 375 degrees F.
In a blender, blend 1 cup plus 2 Tbsp of rolled oats. Blend to the consistency of flour.
Set aside 2 Tbsp. of the oat flour you just made. You will use this later when rolling out the dough.
In a mixing bowl, combine the remaining oat flour, the ground flax seeds and the pumpkin puree. Mix well until a ball of dough forms.
Sprinkle the oat flour you set aside on the counter or a cutting board. Place the dough ball on the surface and roll it out to 1/8" thickness. I find that it is easiest to place a sheet of parchment paper over the dough when rolling it out. This prevents the dough from sticking to the rolling pin and makes it easy to get a uniform thickness.
Cut the dough into your preferred shape. I like to use cute little cookie cutters. Heart shapes and dog bone shapes are my favorite.
Place the biscuits on a parchment lined baking sheet. Bake at 375F for 12-15 minutes (larger biscuits take longer to cook than smaller ones), until the biscuits are just starting to brown.
Remove from oven and let the biscuits cool completely. This is important for two reasons: You don't want to give your dog hot biscuits and the treats will get crunchy when they cool.