Selfish parents use dogs as 'four-legged nannies' to entertain children during summer holidays - then abandon the pooches when schools begin.
Dog re-homing charities have demanded an end to the 'worrying' trend, with some shelters taking in hundreds of dogs in September when schools return.
In the worst cases some parents buy a dog when schools finish for summer before abandoning it just six weeks later.
And other cruel owners even wait until children go back to school before dumping dogs so distracted kids 'don't notice' their pet is gone.
Richard Moore, re-homing centre manager at the national Dogs Trust charity, said parents need to remember the old slogan 'a dog is for life'.
In one case the charity took in a nine-month-old Cockapoo, Gus, whose owners got him when the holidays began then abandoned him when schools returned.
Richard said: "In extreme cases, we're finding people even buy dogs simply to keep their children occupied during the holidays.
"Gus was handed into us because his owners bought him to entertain the children and then passed him to us for re-homing when the kids weren't around during the day any more.
"We hope people will remember that a dog is for life and will carefully consider this lifetime commitment before purchasing a dog."
The Dogs Trust took in 220 dogs last September when schools began and say families should take their dogs to training classes instead of abandoning them.
Maria Wickes, head of the Dogs Trust's dog school, added: "Sadly it does seem to be a recurring trend that we see more dogs handed into us as soon as children go back to school.
"In many cases dogs are not equipped to deal with this change in routine and may start displaying undesirable behaviour.
"We hope that anyone struggling to control their dog's behaviour after the summer holidays will consider giving them up a last resort."
She added: "Whilst the majority of dog owners regard their dogs as valued family members, it appears some may be using dogs as four-legged nannies over the holidays and disregarding them come September."
Battersea Dogs Home said it experiences similar demand during the holidays as families abandon dogs.
The charity, which received 1,400 calls in August about giving up dogs, said some parents will dump pets when schools start so children don't notice they're gone.
And others will abandon their pets because they want to go on more holidays - and don't want the hassle of a pet.
Peter Laurie, deputy chief executive at Battersea Dogs & Cats Home said: "In August, Battersea received over 1,400 calls from people enquiring about bringing their dog into our centres.
"We typically see an increase in enquiries during the school holiday months of July and August, there may be several reasons for this, but we do hear from people who want us to take in their dog so they can go away on holiday.
"Sometimes owners will ask us if we can take in their animals once their child has returned to school to reduce the upset they will face at the loss of their pet."
The RSPCA has urged families to think carefully before getting pets.
Figures show a huge surge in calls to the RSPCA in July, August and September.
It comes after the Dogs Trust said parents buy dogs as pets at the beginning of the summer holidays, then abandon them when school start.
An RSPCA spokesperson said: "Dogs can make wonderful pets and companions but require a lot of time and commitment.
"Any family considering taking on a dog should do lots of research first and ensure they are able to care for their new pet for the rest of their life.
"Sadly many people take on dogs without properly considering the responsibility involved and charities, like the RSPCA, are left picking up the pieces when dogs are neglected or abandoned."
There were 2,812 animals rescued by the RSPCA from July to September 2015 - with the charity experiencing about 25 per cent more calls than winter months.
The spokesperson added: "We see a spike in the number of animals - including dogs - being abandoned over the summer months.
"Although it's difficult to say exactly why this is we believe it may be as people go away on holiday and fail to arrange proper care for their pets, or because the excitement is beginning to wear off from the puppy they got as a Christmas present."