Poll: Do you think dog mess fines have been a success?
The number of fines dished out to people failing to pick up their dog's mess fell by almost 20% last year, new figures suggest.
A third of councils polled in England and Wales did not hand out a single fixed-penalty notice for fouling in 2014-2015, and almost one in six had dished out none for five years, figures obtained by the BBC show.
The overall number of fines fell to 2,868 that year from 3,521 in 2013-2014, its investigation found, a drop of 18.5%.
Sheffield City Council, which handed out zero fines last year despite 1,407 complaints, told the broadcaster it did not have the resources to patrol parks around the clock.
A spokesman said: "We do appreciate that dog mess is an issue in Sheffield, as it is in every city. However, we need evidence if we are going to issue fines.
"In these times of austerity we simply do not have staff available to patrol Sheffield's parks around the clock, waiting for an offence to be committed."
The Five Live investigation received information from 302 of 348 local authorities.
It found 103 did not hand out fines last year. Some 48 had not handed any out for five years, including Swindon, Bournemouth, East Hertfordshire and the London boroughs of Bexley and Merton, which it said between them received almost 8,000 public complaints about fouling from 2010-15.
Barnsley Metropolitan Borough Council issued the most fixed penalties last year (187), and Liverpool City Council issued the most over five years (972), the investigation found.
In April, an east London council introduced dog mess DNA tests designed to catch "irresponsible" owners who fail to clear up after their pet.
In a UK first, Barking and Dagenham said it would encourage dog owners to register their pets on a DNA database, in order to target a "selfish few".
The borough, which estimated it spends £2.3 million on street cleaning, said anyone falling foul of the measures could be fined up to £80 - but a dog welfare charity said it had "concerns" over the plan.
The Department for Communities and Local Government told the BBC it is continuing to work with councils and other organisations "to help find local solutions to littering".
