Hens do not lay in winter.
I beg to differ with that.  I have two hens that only just started laying on black Friday, and doing quite well.  No artificial light use either.  We built a nest box and set it inside the coop, and they took right to it.  We've been getting "egg"cellent eggs.  6 in a week (Friday to Friday) between the two girls.  My hens are leghorns, and leghorns (the white at least) are winter hardy birds.  One of my girls is white, the other is light brown.  If you want a good laying breed, this would be a good one.  There's another site called mypetchickens.com where they have a free "tool" you can use to help choose breeds to accommodate your specifications.  Just go to the site, scroll all the way down, and on the left you will see the 'breed selection tool'.  Click on that, answer the very short questionaire... and it will show you the best breeds for you.  If you want chickens who will lay in winter, click yes where it asks if they need to be winter hardy.  If you want hens that will sit on their eggs, then select yes where it asks if you want them to be broody.  Etc.  
As for the post question.... I'm not sure why your girls are not laying.  I have to agree that they need to feel like they are safe and secure.  And having a nest box offers a little security.  It is a dark, somewhat secluded space where they feel their eggs will be safe.  Make sure their nest boxes are somewhere that would be safe and secure in their eyes.  Maybe add one in the coop with an outer door that you can use to reach in for egg collection.  I would also move them a little ways away from the dogs.  Maybe they feel like they are just a little too close to them, and it scares them.  Make sure to spoil the crap out of them too.  Lots of treats.  "A spoiled hen lays more eggs"  As for throwing in the towel... don't do that yet.  Even if they don't lay during the winter... they may start when things warm up.  Sometimes Spring is cold... so I'd give them until early to mid summer at the least.  If nothing by then, I'd give up on the thought of those girls laying and get other hens that will.  Good luck to you!