An online page set up three years ago to reunite lost cats and dogs with their owners has developed into a rescue charity for abandoned pets.
Pet FBI, which stands for Pets Found By Internet, started on Facebook in 2013 when it reunited 173 animals with their owners and rehomed 20 others.
This year those figures have grown significantly to 1,081 reunited owners and pets, while 49 animals have been successfully rehomed.
The organisation has 10 foster families looking after abandoned dogs in their own homes but it is stretched beyond capacity, which means there are unwanted animals that it cannot give shelter to.
Lisa Patton, a volunteer member with Pet FBI in Londonderry, said it is now looking for premises to help meet the growing demand.
She also advised that the best way to deal with an over-population of unwanted canines would be for people not to take a dog as a pet unless they could make a long-term commitment.
Lisa said: "This is a problem not just in Derry, but all over, and we are increasingly being contacted by members of the public from far and wide asking for our help, but we can't always offer an unwanted dog a home.
"Pet FBI was set up as a social media page where people who either lost their dogs could post pictures and ask the public to keep a look out for their missing pet, or for people who find a dog to post a picture to help trace its owner.
"Over 18,000 people follow our page and we have successfully reunited so many owners and pets that I have lost count. That is great, but we have also become a contact point for people who find unwanted dogs wandering the streets.
"We are an organisation of real animal lovers and the last thing we want is to see a dog go unloved, unfed and unwanted, so when possible we try to find a foster home for these dogs."
Lisa explained that there were times when the demand was so high, some of the volunteers - including herself - had up to seven or eight dogs at their homes at the one time.
"We have had to deal with some really sad cases including one earlier this year involving a wee dog we called Daisy who had been living in a field for months and months," she said. "She had a litter of pups and our volunteers spent four days in the field trying to catch Daisy and her pups, which we eventually did.
"All of the pups and Daisy were rehabilitated and rehomed, but for every call-out like this there are others where we just can't find homes."
The strain on the volunteers is expected to increase even more in the coming days and weeks when many animals given as Christmas presents are discarded.
"We are coming into the time of year when our resources will be stretched even more," Lisa said.
"It is incredible that so many people still do not get the message that a dog isn't for Christmas, it's for life.
"I really cannot stress strongly enough how much thought people should give to taking on the responsibility of owning a pet, especially a dog.
"They need a lot of time and attention for a long, long time, and unless you can commit to that, then don't get a pet.
"Our foster homes are full of dogs that have been discarded and our need for more people to consider fostering an unwanted pet will be even greater than it already is.
"We need all the help we can get. Ideally, we would love some kind-hearted animal lover with a building that isn't being used to offer it to us so we can give more discarded pets somewhere safe and warm until we find them a permanent home."