The urine of bitches is very acidic and can burn and kill grass in seconds!
Harm
Grass can be killed, lawns ruined
Treatment
There is very little that can be done to either stop the dogs urinating or to counteract the contaminated. Watering the lawn as soon as possible after is worth trying and will help to dilute it. Unfortunately, none of the repellents on the market are very effective at actually deterring the dogs in the first place.