If a female dog urinates on the grass they will kill the grass and it will form a circle< or you have grub problems. Talk to your local nursery and ask them what to do.
Grass will die in a circular pattern if a cigarette filter is decomposing on the grass. Dog urine and feces can sometimes cause grass to die or turn yellow in a circular pattern. There are also some insects that may be affecting your lawn. Do a close-up examination of the area to get a better idea of the problem.
Multiple things including recent spills on the affected area of fertilizers, chemical compounds, or even animal urine), fungi, or bacteria can all cause circular patterns of dead grass.
Dead grass in a circular pattern is most often caused by excessive animal excrement, the high nitrogen content can kill plants. If this isn't the case it could be caused by a fungus. The circular pattern is typical of fungal growth spreading out from a center spot.
grass can die in any pattern but it could be doing it because the grass is not getting enough water in that section of your yard so try watering it more
i know of a couple of things one is something being spilled on it like gas or oil or sometime it the pet peep on it or digging it up i know that the chemical burn is the hardes to fix and it take a lot of time digging and replanting the grass
