Right so. I'm still up because our two month old is wide awake and beaming at me.
Wifey recently started expressing breast milk for just such a situation as this. She's fast asleep - I have no boobs - get the bottle of expressed milk out of the fridge and feed child. All good so far?
But just yesterday, we all got up and there was perhaps eight ounces of boob-milk about to go bad. Wifey told me to give it to the dog. I poured it down the sink. It's a bit like kissing your sister or something isn't it? Just me?
Dog was disappoint.
EDIT; generally speaking, dog loves milk.
Once I was offered to taste breast milk, ... no way! She suggests dirty things at times, I call her bad things at times.
Psssh. It's luxury milk! 
The dog won't GAS
Dogs lick their own scrotum, eat shite and all manner of other things out walking so I really don't think boob milk will do any harm? MTFU.
A dog drinking human milk. Human drinking cow milk.
You are all freaks to me.
As long as the dog doesn't figure out the source and cut out the middleman you'll be fine.
You should have made a latte, or an expresso 😉
It's just milk. Fine for you, the baby, the dog, even your wife.