Thought to be a beagle or a foxhound, it is believed to have come from the Cummertrees area.
But, according to reports, the mystery dog has now been loose in the border town for more than seven weeks.
Lee Herron, part of the dog safety charity Harvey’s Army, is trying to locate the canine, which has been affectionately nicknamed Humphrey the Hound, to make sure that it is kept safe.
She said: “I’ve been part of the hunt for this dog for around a week and we are making real progress.
“We hope to be able to get hold of him by the weekend.”
She believes the team have made real progress in gaining the animal’s trust and hope that it will willingly come into their care in the next few days.
She said: “We urge people not to try and grab the dog to try and help the effort. The most help they can be is to report sightings of it to us and we can work from that.
“We get around eight, nine, even ten calls a day at all times and these are incredibly helpful.”
Meanwhile, a Dumfries and Galloway Council spokesman said: “We have had two reports of a stray beagle type dog in the Gretna area over the last few weeks.
“A dog warden has visited the area but so far has been unable to locate the dog.
“None of the complaints related to aggressive behaviour.
“We will continue to monitor and react to any further complaints and would be grateful for any further information members of the public can provide in relation to this matter.”
If anyone sees this dog contact Lee Herron 07841340752