The Dogs Trust says it saw a spike in people looking to surrender dogs in the three weeks following Christmas.
It says it received 186 calls from people trying to relinquish their dog - a 22% increase on the same period last year.
In one instance, it says a man dropped the lead of a young Jack Russell and just drove away.
The charity launched their #PawsForThought campaign in November last year, where they urged the public to 'pause' and think twice before getting a dog for Christmas.
It cites the case of a two-year-old Jack Russell terrier who arrived at the Dogs Trust Rehoming Centre on January 9th.
It says the dog, named PJ, was "cruelly abandoned" at the centre.
"The distressed dog watched from the car park as a man dropped his lead and drove away. With no other option, PJ was taken into the safety of Dogs Trust and is now looking for his forever family.
"PJ is suffering from a lack of confidence which could indicate that he missed out on socialisation in his early life as he is very quiet, spending most of his day in bed and is scared to meet other dogs and play the way a happy dog should."
PJ the Jack Russell | Image: Dogs Trust
Catriona Birt, head of operations at the Dogs Trust, said: "It is painfully upsetting to see PJ, a friendly young dog being discarded in such a heartless way.
"PJ is a particularly sad case which highlights how important those early months are for a pup and how vital it is to make time to socialise and habituate your new arrival in their puppyhood and adolescence.
"Our care team here are helping PJ with basic training and confidence building, and showering him with love and affection. He is now recovering well from the incident and he is looking for a new family who will love him."
Dogs Trust operates at full capacity and offers as many places as possible to dogs from Irish pounds, as they are the ones most at risk of destruction.
Suzie Carley is the executive director: "We are saddened to see an increase in the number of dogs and puppies being surrendered or abandoned after Christmas again this year.
"Dogs Trust urges the public to avoid getting a dog around the Christmas season.
"It is disappointing to see that this message is still falling on deaf ears for many as the number of surrender requests continue to rise."
"PJ is a particularly sad case. He is such a sweet and kind boy and for him to be discarded this way is deeply upsetting."