Yes, dogs can eat marshmallows in small servings.
Marshmallow is a spongy candy. They’re made of sugar and gelatin. Marshmallows are safe for dogs unless dogs have diabetes.
Although small amounts of marshmallows are harmless to dog’s health, but I don’t recommend to feed dogs, especially not feed overweight dogs, because marshmallows have absolutely no nutritional value, and high in sugar food would contribute significantly to obesity.
Of course, marshmallows have some positive effect. Giving the dogs pills is extremely difficult, dogs aren’t willing to eat pills which taste disgusting. Now you can use a small marshmallow to hide the pills, dogs never know the secret, they will cheerfully take the pills.
In conclusion, dogs can eat small amounts of marshmallows. Eating too much is bad for dogs, it can cause an upset stomach. You’d better not get dogs into the habit of eating marshmallows.