My piggies are growing up with a diet based on grass; there are a lot of gardens and lawns here and we also have some rat and some cat around. But cutting grass using a knife 5 cm from the ground is safe. Also at my Nan's veg garden there were wild animals, maybe rats, moles for sure, but those vegs were healthier than the ones on sale filled with nitrogen, chemical products and dirty water; we all know the great problem with salmonella, also on fruits like melons, there is an alert in Usa and Canada, but also in Europe things don't go differently.
Of course I would not go to reserved areas for dogs, although their poo is visible, but fresh grass grows up in a night and you cannot be wrong in finding the best one for your piggie. Vegs on sale have dangerous bacteria as well and are even poor of nutrients. In your country I saw wonderful meadows and you have also the right climate for the best and softer grass. I adopted an underweight pig who doubled his weight in two months eating grass; her urine stopped having calcium residuals and both piggies were checked by the vet who was totally satisfied also for their teeth. I don't give them pellets, only hay and grass, wild herbs (chicory) and some little pepper...
Trust your wonderful lawns... surely cleaner than the ones in Rome...