Dead lawn patches

I have 2 young 'dogs' that have yet to cock thier leg up but the damaged patches on my lawn have the dark green growth around them....So it's not just down to the bitches...

 

As they said, that can be due to pets (cats, etc.).
If pets is not the cause, it could be a "fungus".
That's what I was told some time ago.
In that case a special treatment is needed.
The treatment consist on diluiting a special liquid product (just a few drops) in an amount of water (say 1 liter, less or more depending on the concentration of the diluition needed and depending on the surface-width to be treated and how severe the desease is).
There is a liquid product that kills fungus.
Then you have to spray the mixture of water and liquind on the lawn surface.
Repeat the treatment more than once.
That was I was told time ago when a fungus affected my front-yard grass. The grass became yellow.
But - I say it again - that's the correct solution to the problem ONLY IN THE CASE THAT PETS IS NOT THE CAUSE AND IT HAS BEEN REALIZED THAT A FUNGUS IS THE CAUSE.
That's what I have been told. Thence, if the method doesn't work is not my fault (since THEY told me that).

Bye