Well, better not. It’s definitely not too healthy for them.
A donut is a type of fried dough confectionery or dessert food. They are usually deep-fried from a flour dough, and often filled. In addition to flour, doughnuts may also include ingredients like water, leavening, eggs, milk, sugar, oil/butter, natural or artificial flavors. But, simply, doughnuts are mainly sugar and flour.
Dogs don’t digest food exactly the same as us. Grains, flour, and sugar are just fillers for a dog. They run right through them, and sometimes stick in between.
Too much sugar can do the same thing to dogs that it does to humans. It can lead to obesity, dental problems, and possibly the onset of diabetes.