By the late 19th c. in Belgium ( among other European countries) it was not uncommon for milk to be delivered in a cart pulled by dogs . As there was a vogue for postcards showing local color then ( "la France pittoresque" or " la Belgie pittoresque") you can find plenty more photos of them online.

The Belgians would even use dogs to pull machine guns, at the outset of WWI. Eventually, the practice of using dogs as draft animals was considered cruel, and in Belgium commercial use stopped circa 1930.