The girl was attacked in the Jenkins Dale area of Chatham on 4 April and is still in hospital with serious injuries, Kent Police said.
The dog was shot by firearms officers.
A man and a teenager have been re-arrested on suspicion of offences under the Dangerous Dogs Act. Both had been detained on the day of the attack but released later.
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The teenager was previously arrested over the same offences and the man has been now also been detained on suspicion of supplying cannabis.
A woman arrested on 5 April on suspicion of dangerous dogs offences answered bail on Wednesday and was released pending further inquiries, a police spokeswoman said.
Kent Police confirmed they had received a call from a member of the public shortly before the attack at 17:10 BST about a dog pulling its handler nearby.
They said there was no information "the dog was behaving aggressively or was of a dangerous breed as described under the Dangerous Dogs Act".

The barrister turned politician led the Home Office at the time of the poll tax riots and the Strangeways prison disturbances in the spring of 1990.
On the right of the party, he entered Parliament in a by-election in the 1960s and served as chief whip and other roles under Margaret Thatcher.
After leaving the House of Commons, he served as leader of the House of Lords and latterly as governor of Bermuda.
Prime Minister Theresa May paid tribute to Lord Waddington's "long and distinguished career in public service", saying he would be sadly missed.
"He combined the sharp intelligence of a Queen's Counsel with the wit of a proud Lancastrian," she said.
The Oxford-educated David Waddington served in the army in the 1950s before going into politics and first being elected to Parliament in 1968.
He represented a number of different seats in Lancashire between 1968 and 1974, when he lost his seat, and again between 1979 and 1990.
After rising through the ministerial ranks, he became chief whip - in charge of party discipline - before succeeding Lord Hurd as home secretary in October 1989.
A supporter of capital punishment, he took a tougher line on law and order issues than his predecessor, piloting legislation through the Commons in 1990 to ensure serious criminals served longer sentences.
He stood down after John Major became prime minister in November 1990 and accepted a peerage soon afterwards.
He retired from the House of Lords in 2015.

McAnuff, 31, joined the Royals in 2009 and has made 172 appearances since his arrival from Watford.
He began his career at Wimbledon in 2001 and having played for West Ham, Cardiff and Crystal Palace, McAnuff is keen to finish at the Madejski Stadium.
"From my point of view of course I would," McAnuff told BBC Radio Berkshire.
The squad is so strong we have competition in every position and it is something we have to get on with and deal with
"I've been on record numerous time saying how much I've enjoyed my time here and some of my best moments as a professional have been with this club.
"But it's not my decision. All I can do is do as well as I can on the pitch, it is not solely down to me."
McAnuff, who captained Reading in the Premier League last season, was on the substitutes' bench for their Championship opener against Ipswich but started at Bolton last weekend.
Despite being disappointed at missing out on on a starting spot on the first day of the season, McAnuff is confident he can be a regular in the team.
"In pre-season you come in and work hard and it is all geared up for that first game," he added.
"So it's disappointing (not being selected) but that is football. The squad is so strong we have competition in every position and it is something we have to get on with and deal with.
"The manager makes a point of saying it bears no meaning on the season, it is just a team to get the job done, and as you get older you see the bigger picture and for us this year it is going to be about every single player.
"It is healthy (to have competition), I don't think any player should be guaranteed a place."
Two people have been re-arrested after a toddler suffered serious injuries in a dog attack.
[NEXT_CONCEPT]
Former Conservative Home Secretary Lord Waddington has died at the age of 87.
[NEXT_CONCEPT]
Reading winger Jobi McAnuff says he hopes to end his playing career at the Championship club.