If you have house trained your puppy, chances are he is using your lawn for his bathroom area. Unfortunately, dog urine burns the lawn with an over-concentration of nitrogen. Over fertilization of the lawn can have the same effect. You can recognize these spots on the lawn by their yellow color or dead appearance. There are many methods to repair your lawn and prevent further damage.
Identify the spots in the yard where the lawn is burned. Remove any clumps of dead grass and loosen the soil with a hand claw tool. Flood the area with water from the hose. This will help dilute the urine so that it will actually help the lawn. If you can catch it right after the dog urinates, you have a better chance of saving the lawn.
Pour lime over the area where the dog urinates frequently. This will help alter the pH levels in the lawn to work with the urine to fertilize the lawn.
Replant the lawn with urine resistant grass such as perennial ryegrasses and fescues. Fall and spring are the best times to plant your lawn.
Train your dog to only use one spot on the lawn for his bathroom. This will help keep most of your lawn healthy. You can also put artificial turf, river pebble, gravel, mulch or wood chips down in the area you want the dog to use.
Purchase a lawn repair product from a local pet or lawn and garden store. These repair products will help return small spots of your lawn to a healthy state.