Breeders have to fork out for artificial insemination to impregnate the bitches and pay for caesareans to deliver the puppies safely.
Why would anyone go to all that expense? Well, when a single French bulldog pup is going for $4500 on Trade Me, delivering six of the little scraps successfully would more than justify the veterinarian's fees.
And they're very trendy, at the moment. Especially French bulldogs. Lady Gaga has a Frenchie. Hugh Jackman has one. The Beckhams have one. Madonna has one. And an Instagram account simply isn't worth following unless you have a couple of photos of batpigs – as Frenchies are known by the cool kids.
Lovers of the dogs argue that it's the small gene pool in New Zealand that perpetuates congenital conditions.
One woman told me Frenchies and pugs in the country look completely different to their cousins in the rest of the world because of the inbreeding.
Her Frenchie, she said, was Australian and perfectly healthy and fit in every way.
Others say that while there might be problems with some dogs, their boy (or girl) was absolutely fine – and besides what about other breeds?
What about German shepherds and their propensity for hip dysplasia? Or Cavalier King Charles spaniels, all of whom have descended from just six dogs, and are prone to heart conditions and ear conditions.
And dalmatians, 70 per cent of which are deaf? In fact, the dalmatian is a prime example of how people can be sucked into getting a dog that isn't suitable for their family and their lifestyle.
When the Disney film 101 Dalmatians was released in 1996, mums and dads flocked to pet shops and breeders to buy an adorable black-and-white spotted puppy for their kids for Christmas.
Many of the breeders were disreputable, backyard types who just wanted to cash in on the Disney dalmatian phenomenon and had no concern for the animal's welfare.
The doting mums and dads hadn't factored in that these gorgeous wee pups grow into highly active, 25-30 kilo dogs who need to be stimulated and exercised. Because many of them were deaf, they were often startled by the actions of children behaving unpredictably and in response, they would nip or bite.
The upshot was that in the US, within months of the film being released, thousands of dalmatians were let loose on the streets or in parks or dumped at animal centres, and thousands of them ended up being killed.
And it happened all over again when 102 Dalmatians, the follow-up, was released.
The owners of bulldogs and pugs make a fair point: there are a lot of purebreds in this country that are not only expensive to buy, but bloody expensive to care for over the course of their life because of the excessive interbreeding.
If you're looking for a pup for your family, do your homework.
Will it fit into your family's lifestyle? Will you be able to care for it properly – exercising it daily, providing it with companionship and being able to pay for its medical care if necessary?
And take the advice of radio vet Alex Melrose and animal trainer Mark Vette. If you want a dog, go to the SPCA and get a mongrel. As Alex said, he'd go out of business if we ignored the fashionable inbreds and went for a bit of rough.