Hello Rosemary! here's a few suggestions for you. https://www.wikihow.com/Repair-Spots-from-Pet-Urine-in-Lawn-Grass
I usually go around my yard with a regular size rake and a small hand garden rake and rake out all the yellow grass to the dirt. I scratch up the dirt, sprinkle grass seed in that spot, cover with about 1 inch to 1.5 inches of top soil, water, and wait for the grass to grow. You can use an annual quick grass seed that has rye in it and it will come up quickly, however annual rye grass will die over the winter. I reseed these spots with perennial grass seed once the rye comes up. The rye will help hold the perennial grass seed in place until it germinates. It is a process I have to go through every year...the price of having a dog who can wander the yard and go where he wants. I have a big yard and it's just so much easier to let the dog out on his own to do his business rather than walk him around on a leash. I think that's what most of us do. The other solution is to train the dog to go in one spot only.
GK's suggestion sounds like a winner!
To prevent in the future, if this is from your dog, make sure the dog drinks plenty of water. Also a female dog that has not been spayed, will have more estrogen in the urine , which supposedly will cause more damage.
Female dogs usually are the source.
I make sure to water the heck out of that spit to dilute it, before amending the soil & planting some seed.
This tutorial should help: https://www.countryliving.com/gardening/a38148/how-to-fix-dog-urine-patches/