My question now is, if the dog urinated on top of the snow in winter, does that soak through and still damage the lawn?

Yes and no. It would really depend on how much snow you've got. The damaging element in dog urine is the urea (not the acidity as many people believe. Urea is a form of nitrogen and what it is doing is giving your lawn and other plants a fertilizer overdose/burn. Water will dilute it so that it is not strong enough to burn, so if you have enough snow that it is sufficiently diluted by the time it gets to the grass, you'll be ok. If not, then it'll still burn.

A deciduous shrub will be less likely to be damaged than when it is in leaf, but it will still suffer.

Several other things affect how badly your lawn will burn from the dog urine. A truly healthy lawn can handle quite a bit of dog urine and not suffer burns. Monoculture grass lawns are more prone to it than lawns with clover. Lawns cut below 2" in height are more susceptible. Infrequent watering is another factor. These conditions will also encourage grubs which will also cause the remaining lawn to be more stressed and prone to burning. If you regularly fertilize it then it may be perilously close to being overfertilized by a dog. If any of those conditions apply to your lawn, you might want to change the way you care for it - it will then be able to tolerate the dog without so many brown spots.

How well you get along with your neighbour and how well you want to continue to get along are important things to keep in mind! Of course your neighbour is being inconsiderate and is also likely breaking leash laws, but getting on her case about it might cause her to become so peeved that she deliberately encourages the dog to use your lawn. If you have a good enough relationship (or if you don't care about her at all), you could get an estimate from a professional lawn company on how much it costs to repair the damage and present her with it. That might knock some sense into her about how much $ damage her dog is causing.

If your neighbour thinks that 'trying' is good enough, then she's not really a responsible dog owner - you're going to have a real uphill battle convincing her to change her ways. The only real way to keep the dog away is to either build a fence ($ for you), get your neighbour to build a fence, or use the threat of suing for damages to force her to keep the dog in or leashed. Good luck! People not taking responsibility to contain or clean up after their animals is a major peeve of mine too :-)

BP

There is no doubt that dog urine can cause damage to lawns and small shrubs, and the urea of a female dog will be deadlier to a lawn than that of a male due to it's higher concentration.

I have a Black Lab, female, and a Valley Bulldog, male. In the winter. they both do their jobs where there is the least amount of snow, and that happens to be on an area of our lawn. By spring, these spots are wickedly ugly, but by mid-June, because of the rain and the fact that they are doing their job in a more spread out area, those spots are gone. In the spring, I also treat the spots with leftover pop and high sugar content leftover drinks and such. Seems to help since the sugar increases micro activity in the soil and helps to wash out the urea remaining there.

In terms of the small shrubs, this year I've placed small fences around mine to prevent the Valley Bulldog from aiming things straight at them. This has helped considerably. We had tried to plant a forsythia in a particular spot, but the shrubs we planted there always died. One day we noticed this was Chewie's preferred spot. After fencing it, the new shrub planted flourished. In a couple of years we will be able to take the fencing out since the shrub will be more mature and be able to take his 'shots'.

But these are my dogs, so I tolerate and try to think of ways to work things out. My dogs know not to run through the perennial and annual gardens. Any other dog shows-up on the property, they have to be on a leash because I won't tolerate them running amock!

I would be telling my neighbour that if they don't wish to train their dog to use their side, then they will have to pay for the damage. But then again there's that 'get along with the neighbour' thing...

I would shovel the ice or snow (and pee) from that spot onto her yard before it melts in the spring, or as soon as she is gone.

Sorry about your troubles. Rather than having to play vigilante on the neighbor's dog's bathroom habits, perhaps it's time to put in a visible barrier in between yards. No matter how small the front yard can be, there should be a way to go about it like planting a row of small plants to designate the space. I had a small front yard before and the way I divided the front property was to dig down and set in a lawn edger. I then planted a row of lavenders. As for irritating dog habits which I have many occasions to experience from non-neighbours walking in our street with their pooches, I sprinkled very liberally critter ridders and did so very regularly. It helps. Dogs hate anything very lemony as well.

One thing that hasn't mentioned about dog urea-- although rare with vaccinated dogs, are the parasitic creatures that may come with it - especially if the dog suffer from illnesses like heartworms, etc... One can imagine what that does to barefooted young kids.