Bella, an English springer spaniel, was taken from outside Tesco in Rothwell in October. CCTV showed a man untying her.
Earlier this week, she was found 130 miles (210km) away in Bristol and reunited with the Osborne family.
Her owner said she was "in very good spirits" but her paw injuries "suggested she had tried to escape".
Sarah and Philip Osborne had been searching for Bella since she was stolen moments after Mr Osborne popped into the shop.
After four months she was spotted by a shopkeeper in Bristol, who took her inside believing her to be a stray.
"A family came in trying to claim her, but the woman refused to hand Bella over because she was cowering under the counter," Mr Osborne said.
Bella was scanned and her microchip led the RSPCA to the Osbornes.
They were reunited with Bella in Bristol on Wednesday.
Back home, Mr Osborne said 48 hours after her ordeal ended, Bella had settled in well, recognised all the old smells and "most bizarrely it's like she's never been away".
However, she needs on-going treatment for several injuries sustained during her time away.
"She had been well-fed, but has sores on her paws where she'd been scratching to get out of wherever she was," Mr Osborne said.
She also has problems with her ears, eyes and gums.
"Bella must have been desperately unhappy.
"She smelt like a farmyard so must have been kept outside which is not what Bella knows," he added.
Mr Osborne took her for her first proper walk on Thursday evening.
"We were swamped by people asking about Bella. It was 45 minutes before we could finish our walk," he said.
"I just want people to know how important it is to microchip your pets. The chip is the be-all and end-all."
Northamptonshire and Bristol Police are investigating.
A dog stolen in Northamptonshire and found four months later in Bristol has settled back in with her family "like she's never been away".