Another dog one...garden used as dog toilet

[DuchyCazalet]

We visited a family member and were disgusted to see their back garden. It appears that it's their dog's toilet. Weeks of poo on the grass. Bizarrely they even had some poos bagged up but then just left there, rather than putting in the bin. It's not a large garden by any means and is surely now totally inaccessible to their kids.
They are mid terrace and there are fences on both sides so not directly affecting the neighbours but can imagine that in the summer it will stink. Could the neighbours make a complaint somewhere?

Yes the neighbours can complain to the council.

Eg
www.chesterfield.gov.uk/health-and-environment/animal-and-pest-control/dogs/dog-fouling/report-dog-fouling/dog-fouling-in-your-neighbours-garden.aspx

God are they my neighbours, exact same problem terrace house small garden. Their car is also a total tip, they opened a door and a load of empty cans fell out, instead of sticking them in the bin they put them back in the car! Trouble is if you make a complaint they know it either you of the other neighbour.

That's absolutely FOUL!!! We don't let our dogs use the garden - we take them to nearby woodland and pick it all up. That garden must be absolutely filthy and so dangerous for children