A dog called Harry died after being attacked in the back of a van belonging to a professional dog walker.
The fatal mauling led to the dog walker, Michael Rumball, 49, of Edward Street, Brighton, appearing before magistrates but the case was dropped.
Mr Rumball, who owns the dog walking business Walk This Way, denied breaching the Animal Welfare Act when he appeared before the Brighton bench.
Brighton and Hove City Council, which brought the case, said: “The case was dropped due to a lack of national regulations surrounding the transportation of animals by dog walking firms.”
Now Harry’s owner, Denise Allen, 52, is calling for better regulation of dog walkers to prevent other deaths.
She said: “There should be hard and fast rules in terms of transporting animals and the care of animals. It shouldn’t be left to the goodwill of people.”
She has been raising awareness of the issue in the hope that Harry, a two-year-old French bulldog, didn’t die in vain.
Stephanie Williams, an animal welfare officer at the council, agreed about the need for clearer rules.
She said: “We feel very strongly that there should be national legislation around the transportation of animals by dog walking firms.
“At present dog walkers can carry any number of dogs unrestrained in the back of their vehicles.”
The council already runs a voluntary Professional Dog Walkers Scheme. It was set up three years ago when it was believed to be the first scheme of its type in the country.
Owners of dog walking businesses are able to register with the council and sign up to a code of conduct.
The code includes a requirement that dogs are protected from each other by adequate cages or containers. Harry and the dog that mauled him were not in cages.
More than 50 dog walkers have signed up to the scheme, according to the council. They are subject to checks by animal welfare officers.
The council said: “We know there are many more businesses which haven’t yet registered so we are inviting them to get in touch.
“We would also advise dog owners looking for a dog walking service to ask if the business has registered with us and passed our inspections.”
Councillor Pete West said: “Dog walking is big business in Brighton and Hove and the number of businesses setting up in the city has grown rapidly as owners return to work or work longer hours.
“We want to help ensure that residents’ pets are in safe hands and our Professional Dog Walkers Scheme will help to promote reputable companies in the city.
“We’ve already had a good response from businesses keen to get the council’s seal of approval and we look forward to welcoming many more.”
Dog walkers can find out more by emailing the animal welfare team at firstname.lastname@example.org.
The charity dealt with 4,168 offences in 2012, up from 3,114 in 2011, and it said that 1,552 people were taken to court, up from 1,341 or an increase of 15.7 per cent.
It said that there was “a growing animal cruelty crisis”.