Years ago at a veterinary convention I listened to a talk about brown lawn spots. The speaker had done some casual experiments using dog
urine he had collected. He determined that the more concentrated the urine, the more apt it was to kill the grass. He also discovered that if he poured at least an equal amount of
water on the spot after the urine had soaked in, the grass was not killed.
Conclusions:
... Hose the urinated area, or dump a
bucket of water on it.
Or
...Do something to encourage the dog to drink more water so that the urine isn't so concentrated.
Or
...Set up a potty area and train the dog to use it.
The assumption that people make is that the urine is too acidic. But this person did not find a correlation between acidity and grass kill. By the way, dog urine, like human urine, is mildly acidic. The pH doesn't fluctuate wildly, but the concentration can.
One more point, he found a connection between lush growing grass and urine kill. The more lush and fertilized the lawn, the more sensitive it appeared to be to urine kill. He was using Kentucky blue grass lawn for his trials.