This is the time of the year when dog urine injury is quite visible on lawn areas.
You may see only green circles, the result of response to the nitrogen in the urine. Dead-looking grass is the result of salt injury. Try watering these spots (by hand) very heavily, to dilute and leach the salts. The centers may come back with heavy watering. If the grass appears to be dead, you can scratch up the centers with a small hoe or rake, or create holes with a foot aerator, and seed with good quality Kentucky bluegrass or perennial ryegrass seed (use tall fescue seed ONLY on tall fescue lawns). The seed must get into contact with the soil, and not merely sit on top of the soil. Scratch the seed in lightly and then firm the soil by stepping lightly on it by foot. Keep the spots well watered to prevent residual salt from inhibiting seed germination and seedling growth. Be aware that the ONLY effective material that can be applied to these spots to reduce the saltiness is water. Don’t apply water and baking soda, or water and vinegar, or water and dishwashing detergent, or water and anything else. Pills and other food additives sold in pet food stores, with claims of preventing dog spots, do not appear to work and may actually be harmful to a dog’s health.