Ireland's largest dog welfare charity said it has experienced an 82% increase in the number of people wanting to give up their dog this year.
Dogs Trust Ireland has received more than 2,150 requests from members of the public trying to rehome their pet.
The most common reason given was behavioural issues.
The charity said it was particularly concerned about where dogs were being sourced, with the prevalence of puppy farming in Ireland since the beginning of the pandemic.
It said the demand for dogs since the onset of Covid restrictions saw prices soar into the thousands for puppies being sold online.
Ciara Byrne from Dogs Trust Ireland said: "We are pleading with the public not to purchase puppies in the run up to Christmas.
"Sadly, this is the most lucrative time of year for puppy farmers, and we know genuine dog lovers don't want to fuel this vile trade."
Ms Byrne said it is not just the puppy that is affected but its parents, who are left behind "in often appalling conditions", that suffer the most.
She said that is why the End Puppy Farming campaign was launched in November.
"We want to show that the public wants to see an end to the horrors these poor dogs endure daily, all in the name of profit," she said.
Speaking on RTÉ's News at One, Ms Byrne said many dogs have been surrendered due to behavioural issues, while some owners were not aware of the the amount of time and responsibility dogs require.
She said they take in hundreds of dogs each year and do their best to rehome them, but they are full to capacity.
Executive Director at Dogs Trust Ireland Becky Bristow said: "Due to the nature of the puppy farming industry it is extremely difficult to buy a puppy responsibly at present.
"Advertisements of cute puppies online in home environments are often a smokescreen and the same photos are often used repeatedly. If you are considering getting a dog, please visit our website for advice."
The charity is urging people to sponsor a dog instead of buying a puppy this Christmas.
"You can save lives and give abandoned Irish dogs the second chance if life that they deserve so much," Ms Bristow said.