Pet urine and feces can cause spots of dead grass on your lawn, damaging the entire area. The high nitrogen concentration in pet urine and feces is what causes the damage, often resulting in fertilizer-burn-like damage. You may even see a ring of healthier, vigorous grass growth around the spot of dead grass, where the less-concentrated urine actually fertilized the grass. There are several things you can do to prevent pet damage on your lawn, but only a few remedies for when the damage is already done.
Water the area to soak the ground and dilute the pet urine as soon as you see the cat or dog urinate. It's best to do this immediately, but can also be done up to nine hours after urination. Apply at least three times the amount of water to urine to the grass.
Re-sod or reseed the area if the damage is severe. Dig up the affected sod with a shovel, and replace the bare spot with new grass seed or sod. For sod, just put the same size piece into the dug up area. For seed, sprinkle a handful of grass seeds on the area and water. Replant the areas in your lawn with perennial ryegrass or fescues, which are more resistant to pet urine damage.
Prevent pet damage to your lawn by training your pets to go to the bathroom only in certain areas. Designate an area in your yard for the pet to go to the bathroom that's a patch of mulch or gravel.