Pups are being sold at hugely inflated prices across Northern Ireland with many unlicensed breeders flouting the usual good practice around buying a puppy, according to the USPCA.
Some of the pricier puppies include English bulldogs which are currently on sale for anything up to an eye-watering £10,000.
Golden retriever and poodle crossbreeds, aka goldendoodles, are being flogged at up to £3,000 per pup.
Other popular breeds including Shih Tzus, French bulldogs, cocker spaniels, Yorkshire terriers, chihuahuas and Pomeranians are also being flogged for thousands on websites like Gumtree and Pets4Homes.
Many established, respected dealers stopped trading due to social distancing rules and dodgy dealers took advantage to cash in.
Colleen Tinnelly (38), development manager at the USPCA, says the lockdown has caused an increase in pup prices and dodgy breeding practices.
She said: "When lockdown started we had an influx of people looking for animals and at that point we put a stern message out, similar to the one we put out at Christmas, because we were concerned about it creating a demand.
"Unfortunately it did create a demand for puppies and that fuels the illegal puppy trade. We don't have any issue with licensed breeders, it's the illegal breeders and puppy farms that are just looking for a quick buck.
"The money changing hands at the moment is just crazy. There has been such a drastic increase in demand that it has created this explosion in pricing.
"I have seen cockapoo puppies listed for sale at £2,250 which is huge, that's the price of a car.
"I've also seen Jack Russell puppies advertised for £1,250, this is a breed where puppies are normally sold for about £250 from a licensed breeder, it's incredible.
"Also, during lockdown sanctuaries have been unable to re-home but have had a huge influx of people looking for animals; so when people have been contacting us we've been having to tell them they need to wait which hasn't helped.
"Also from an animal welfare perspective it's not only fuelling the illegal puppy trade but some of the practices are very worrying.
"We always put out strong messaging about people checking with the breeder and about being registered and checking out the mummy.
"What we've found is that the public are telling us when they ask to see the mum the excuse of Covid-19 is being used.
"Our messages is always 'don't buy your puppy from the side of the road' and they're using the pandemic as an excuse to get around that."
In May, Scotland's animal welfare charity, the Scottish SPCA, rescued 13 puppies from an illegal dealer who had travelled from Belfast to Cairnryan Port in Dumfries and Galloway.
One puppy was so ill it had to be put down and another required emergency vet treatment for breathing problems.
Ms Tinnelly also said the trade in puppies by unlicensed breeders was creating an animal welfare problem.
She added: "It's extremely worrying from an animal welfare point of view and is very much down to demand.
"We understand animals have been lifelines for people throughout this pandemic and have been their only company in the household in some cases.
"But what we are telling people, and have told people, is just be sensible. When you go back to work what happens to this puppy or kitten then?
"Unfortunately when there's a very cute animal involved it's difficult but all you are doing is fuelling demand for these illegal puppy farms.
"The public really need to be very sensible, unfortunately demand has pushed up prices and we will continue to ask people to check the breeder is registered and check the welfare of the puppies and the mother.
"We will also be pushing for more regulation of the online sales, that is something we would very much like to see.
"We feel heightened regulation, or even bringing us into line with England, will help. It's just about the public being aware there are so many dogs looking a second chance in rescue centres, dogs which are lovely creatures and just need a home.
"That's why we would always encourage people to adopt rather than buy and be mindful about their role in creating the demand."
In mid-May, the UK's largest dog welfare charity warned people 'dogs are for life, not just lockdown.'
Dogs Trust chief executive, Owen Sharp, said at the time: "Dog ownership can be so rewarding, but it's also a huge responsibility, which is why we are reminding people today that 'a dog is for life, not just for lockdown'.
"Are you ready to be chief pooper scooper? Are you ready to forego a lie-in for ever? As well as more serious questions around vet treatment and preparing for emergencies.
"If there is still a dog-shaped space in your life, then it may be the right time for you."