Today 
Dog urine contains a very high concentration of nitrogen. While nitrogen can produce a fertilising effect that promotes growth, large amounts in a concentrated area can result in dead patches of lawn. Bitches in particular cause the greater damage, because they tend to urinate in one spot, rather than dogs who tend to mark many spots and pass small amounts.
Solution
Organic
The most effective solution is to simply spray the affected area with copious amounts of water as soon as possible, to neutralise the urine. You could also try adding horticultural lime or powdered gypsum to the water, as this will neutralise the acid, their high alkalinity restoring the pH level. Finally, try to prevent the problem by encouraging your dog to urinate in a designated area of the garden.
