H Ryder wrote:
...seem to have enjoyed using the
lawn as a toilet as there are many bare patches on the lawn at the moment

it may not be the dog and cats - in my experience cat urine does not kill
grass, and I think that dog urine (as opposed to bitch urine) doesn't
either.

If they were bitches then you heed do nothing, the patch will come back
greener and healthier than the surrounding grass! We have two bitches
and lots of 'green patches' that need cutting a week before the rather
poor lawn.