Dogs Trust Ireland says Irish dog owners have been victims of "dog-fishing"- where a puppy purchased online arrives and looks nothing like its picture.
The charity has received 297 surrender requests since Christmas Day, a 73% increase on the same period last year.
Meanwhile, other owners have decided to give up their pet after breeders promised the dog was hypoallergenic when that wasn't the case.
Dogs Trust has issued an urgent appeal for people willing to foster a dog to come forward, so they can continue to help as many pups as possible.
Ciara Byrne, Head of Communications at Dogs Trust Ireland said: “While many of the people who contact us do so because of extenuating circumstances, sadly many are telling us they underestimated the commitment dog ownership involves.
"We are also continuing to see victims of unscrupulous breeders and families being ‘dog fished’ as misleading and often illegal online advertisements continue."
She continued: "Dogs are often advertised as being ‘hypoallergenic’ but as the causes of individual’s allergies can vary, no dog can be said to be 100% hypoallergenic, even if the breed or crossbreed doesn’t shed very much or the dog doesn’t have much or any hair.”
