Those patches out front do look like burn patches from dogs to me. You could try googling for some remedies. I usually just dig them out and seed or buy a roll of sod and cut to fit the area as required.
+1
If you see a dog relieve himself on your lawn, heavily water that spot asap. Urine is comparable to a 500:0:0 fertilizer.
The problem with most fertilizers is that they also make the grass grow super fast, which translates into more cuts. Not so bad with a small area, but on the acre I've got, it's a huge time sink.
Scott
