Looks like it is my angry at the world week

Neighbours have a 6 month old puppy. Gorgeous thing - a poodle spaniel cross - apricot colour.
except . . . . .
The household next door has nanna who is 92, the parents who are in their late 50's and a 21yo daughter. We have been neighbours for 6 years, and until now have got on really well - I often used to go next door to play canasta with them etc. He used to drive taxis for a living and she was a stay at home mum. They got the puppy about 4 months ago, and she just used to let the puppy roam during the day. A couple of times I caught it trying to get through my fence to my chickens, and took it back home. Neighbours still dont have side fences. About 2 months ago they opened their own business, so they are now both away from home 8-6 Mon-Fri, plus Saturday mornings. They are working hard, and I wish them all the luck.
BUT
they still have done nothing about keeping the dog in. They have a dog door in the laundry then nothing (no fences, gates etc). I have seen the dog roaming up to a kilometre away - and only 600m in the opposite direction we have a main road with 4 lanes - this is a recipie for disaster.
Just now my son opened our side gate to take the rubbish out, and the dog ran in. Chickens squawking everywhere. It took me only 3-4 mins probably to catch the dog, but it seemed much longer - and the chickens are now frantic. I hauled the dog next door, knocked, nanna came (a truly lovely lady) and I told her what had happened. Also told her that I had seen the dog wandering near the main road. Told her that it was a lovely dog and deserved to be better looked after - and if i saw it wandering again, or if it came anywhere near my chickens again, I would be ringing the council.
I know it is not her fault - she is old and uses a walker etc, I kept apologising to her. But really - people who have pets and dont bother fencing them should be shot.
So, on the one hand I feel bad for threatening to contact the council - but on the other hand I will feel worse if the dog gets run over, or eats one of my hens in front of my children.
Should I have just let it go? Am I really just angry at my ex and taking it out on poor nanna and puppy?