Dogs and Lawns
It has been my experience that most people who enjoy gardening also love animals. Sometimes this is a difficult relationship to balance, especially when it comes to maintaining a healthy lawn and living with a dog.
Brown spots that appear where a pet uses the bathroom are the result of nitrogen burn. Nitrogen is a by-product of protein breakdown. Ironically, a healthy, green lawn is more susceptible to animal spots because the nitrogen content is high from regular fertilizing. So it takes less urine to raise the concentration to toxic levels for the grass.
The problem is worse for gardeners who live with female dogs simply because a female dog will urinate larger amounts in one spot at a time. Male dogs tend to rove around, marking their territory with smaller amounts.
I have come across many so-called solutions such as changing the dog's diet or giving the dog tomato juice, but in reality there is no quick fix for this problem.
If you are frequently with your four-legged friend when she heeds the call of nature you can flush the area with water to reduce the nitrogen level. However, this takes quite a bit of vigilance and you run the risk of over watering your lawn.
The best thing you can do is to train your dog to use certain areas of the garden. This can be his or her special plot of grass or an area covered in gravel or (bow-wow) bark.