Officers have yet to determine what breed of dog is responsible for the attack, although witnesses claim it looked like a Staffordshire or Pit Bull Terrier.
Elvis, a seven-year-old Pomeranian, was playing in a garden on Kingsway South, Latchford, at 4pm on Saturday when he barked at another dog walking past.
The animal burst through the gate, snatching Elvis in its jaws and ripping his head off.
Witnesses say the dog then spat out Elvis’ head after being pulled away by its owner.
Mum-of-three Gemma Antell, aged 30, of Fearnhead Lane, owned Elvis who she describes as ‘friendly, attention seeking and harmless’.
He was being looked after by mother-in-law Margaret Antell on Saturday while Gemma celebrated son Lincoln’s sixth birthday.
Gemma said: “It was like something out of a horror film, like it’s not actually happened.
“My children are distraught. It is the first thing they have had to lose and it’s completely changed the way they see dogs as they are now terrified, which is very sad.
“Elvis would never hurt anyone. The kids have grown up around him and he hardly had any teeth because with his breed, they fall out.
“Everyone loved him and we couldn’t walk down the street because people would want to stop and stroke him. I am still in shock. At least it wasn’t a child, but he was our loved family pet.”
Pictures of the dog and owner, with blood on her arm, have gone viral on social networking websites.
It is believed police are due to interview the owner on Wednesday. The dog was seized on Sunday night.
Chf Insp Darren Hebden said: "This was a horrendous attack and was clearly very distressing for the owners to witness.
“I am aware of pictures that have been circulated on social media which will undoubtedly cause concern for the community but can I reassure people that we have now seized the offending dog so there is no risk to the general public.
“We will be speaking to the owners in due course and will do all we can to deal with the incident appropriately within the guidelines of the law."
Patrols have been increased in the area to reassure residents.
Anyone with any information can call police on 101 quoting inc 788 of July 6, or Crimestoppers, anonymously, on 0800 555 111
(This is Cheshire - July 8, 2013)