When a dog urinates on the lawn, it often causes a dried-up brown spot to form. A lawn that is well cared for can start to look shabby very quickly if your dog or your neighbors' dogs keep peeing on it. The urine from both male and female dogs causes brown spots because urine is high in nitrogen. This excess of nitrogen causes burning in the same way over-fertilization does.
Prevent nitrogen spots by dousing the urine with water as soon as possible. This helps dilute the urine and can actually make it into beneficial fertilizer. If the dog tends to pee in the same area, give that area water once or twice a day. Urine that is diluted within eight hours usually doesn't leave a patch.
Reduce the amount of nitrogen fertilizer you use in areas where a dog urinates frequently, or eliminate nitrogen altogether for that area. It is an excess of nitrogen that causes the burning, so brown spots should be reduced without the extra nitrogen in the soil.
Rake away the dried-up grass in a brown spot to expose the soil underneath. Use a garden fork to turn up and aerate the top few inches of the soil.
Sprinkle grass seed liberally over the turned up soil. Make sure all areas of the patch are covered with seed.
Cover the seeds with a thin layer of compost. There should be just enough compost to cover the seeds. Tamp the compost down gently with your foot.
Water the seeds in well, and make sure the area stays moistened while the seeds are germinating.