Milk is a great diet for dogs all life stages - puppies, adult dogs, and senior dogs. Some situation such as for puppies that their diet can be replaced with milk when the mum of the puppies can't produce enough milk or not around to provide breastfeeding for their puppies.
However, dog milk should be consumed in moderation or not use as a long term feeding dog food as they might not have enough necessary nutrients for your dogs and unlike puppies in the early growing stage, dogs ability to digest lactose will weaken as they grow.
Alternatively, there are many complete balanced dog food from the Dry Dog Food, Frozen Dog Food, Dehydrated/Freeze-dried Raw Dog Food or Canned Dog Food categories at Pawpy Kisses Singapore.