As a treat, you have nothing to be concerned about - a good quality sausage is definitely better than all those crappy store bought treats chock full of sweeteners and artificial ingredients.
I wouldn't make it a main staple of the diet though.
Whether raw pork is safe to feed depends on the area of the world you live in. Aujeszky’s disease (also called pseudorabies), a highly contagious disease in animals caused by porcine herpesvirus-1 is still an issue in some areas and is highly fatal in dogs.