"I swear I'm not a crazy cat person," says Lora. The US-based owner of Luckysuperstarcat — a Persian cat with nearly 95,000 Instagram followers — does not want to give her surname, but insists she's just a normal pet owner.

Key points: Cats and dogs with deformities are a hit on social media

Cats and dogs with deformities are a hit on social media Vets warn that this encourages inbreeding and health problems

Vets warn that this encourages inbreeding and health problems Owners say this is far-fetched and the animals are healthy and loved

She is surprised by some aspects of Lucky's fame though.

"You have no idea [the sorts of messages I get] people have asked me to record Lucky's snorts and sell [them on] CD," she says.

But Lucky's celebrity pales when compared to the latest pet sensation: Britain's Wilfredwarrior, whose followers jumped from 40,000 to 400,000 after two of his videos were repurposed by a US comedian last month.

"Since then Wilfred has gained thousands of followers each day, gaining as many as 30 to 40,000 new followers on some days," his London owner Jenna Millward tells the ABC.

Then of course there are the heavy hitters like Manny the French bulldog with 1.1 million followers.

All this popularity amounts to more than just friends though, it comes with the added bonus of financial gain — for example, Manny sells wall calendars and makes donations to doggie charities, Wilfred has an online store in the works with tote bags and wall clocks, and then of course, there's Grumpy Cat who was last estimated to be worth millions of dollars.

But while many social media users and a number several media outlets have revelled in the unusual appearance of these animals, veterinarians are anxious to point out the myriad health problems they can face.

Loading...

When will I be famous?

In 2015 the New York Post ran an article with the headline: How To Make Your Pet Insta-famous In 4 Easy Steps.

Among the tips it provided, one was particularly revealing: "Pets with a distinct look are more likely to gain a following because they're memorable."

"Muppet (@muppetsrevenge), hardly had an internet presence before enduring the same tooth-removal surgery as her sibling, causing her tongue to hang out too. Months later, she has over 25,000 followers."

Australian Veterinary Association president Dr Paula Parker says vets are very concerned by portrayals of animals with deformities, in particular brachycephalic or flat-faced breeds.

"These animals look really cute; a lot of them can have great personalities and people do love them, but they come with a whole lot of health problems associated with their flat faces," she tells the ABC.

"The heartbreaking thing is that often people don't realise or understand what those problems are."

Dr Parker says among the biggest issues are dental problems and eating problems from protruding jaws and teeth, breathing difficulties due to having a flat face, and tear and mucous problems around the eyes in cases where tear ducts are improperly formed.

RSPCA veterinarian Dr Bronwyn Orr says the popularity of various breeds on social media and with celebrities is encouraging people to seek out pets with abnormalities of their own.

"For this reason, many veterinary associations and companies are choosing not to use [flat faced] breeds like pugs and French Bulldogs in their advertising," Dr Orr tells the ABC.

Lucky's owner says she once gained over 60,000 followers from a single post. ( Instagram: @luckysuperstarcat )

However, owners of some online pet celebrities have argued that many cats are rescued or bought from responsible breeders, are regularly checked by vets, and are not suffering.

Loading...

They say there's a stark difference between celebrating an individual animal and promoting the inbreeding of others.

Wilfred's owner, Jenna Millward, says his underbite is a common condition and not a serious health issue.

"It seems quite a far-fetched concern to me that breeders, who hopefully are responsible, will begin to attempt to breed deformities into their cats in order for them to look [similar to] a cat on Instagram," she says.

"This would be highly irresponsible and risky — most breeders aim for show-cat looks, Wilfred would not make the cut!"

"Wilfred's breeder was reputable, with a lineage of healthy and successful Chinchilla Persians and we received all of his pedigree papers [as well as his] lineage and health certificates.

"Wilfred is in good health; no issues at all."

Lucky's owner Lora says she took her in because she was the runt of a litter that no-one wanted and said she had been given the all clear from a respiratory specialist.

"There has been a bit of negative feedback, but keep in mind Lucky was truly not wanted as a kitten and we have provided a loving home and family for her, alongside excellent veterinary care."

This French bulldog's hind legs have been paralysed since birth and now requires the aid of a roll car. ( Reuters: Ina Fassbender )

Cuteness induces a caretaker response from humans

Veterinarian Dr Anne Fawcett from the University of Sydney says there's good reason why humans are so obsessed with animals with certain features over others.

"As humans we are very drawn to creatures that appear cute," she tells the ABC.

"But some of that 'cuteness' actually represents pathology — whether it's a malformed airway in [flat-faced] breeds, missing bones in 'twisty' or 'kangaroo cats' [shortened forepaws], or missing cartilage in chondrodysplastic [dwarf] breeds."

Loading...

Research has indicated that we find human and babyish features such as large eyes, round faces, and small plump bodies in animals cute, which induces a sort of caretaker response.

However, Wilfred's owner Jenna Millward says that while Persians are known for round eyes and expressive faces, what is depicted online is not always the reality.

"We do get many concerned messages, but actually his eyes only look that way when he is excited or curious," she says.

"A lot of the time his eyes look very conventional, but we know that people mostly love to see his face at its most expressive!"

That doggy in the Insta post

But it's not just purebred felines that experience problems, vets warn.

Pugs commonly experience breathing issues from their flat faces, as do French bulldogs who often also have hip and leg issues; and some types of spaniels have skulls so tight they have constant headaches which can result in seizures and death.

Selective inbreeding to achieve a desired look is often the culprit here.

"Despite widespread media coverage about the health problems of these breeds, they are actually increasing in popularity not decreasing," Dr Fawcett says.

"The unfortunate thing is that some unethical people have seen the demand and tried to take advantage of it, which is awful for companion animal owners but also the breeders who are trying to do the right thing."

French bulldogs and pugs have become immensely popular in recent years.

In 1986 there were 44 registered purebred French bulldogs, according to figures from The Australian Kennel Council.

By 2017 there were 4,082.

For pugs the number of animals went from 522 to 1,506 in the same period.

Loading...

Both the Australian Veterinary Association and the RSPCA have launched the Love Is Blind campaign encouraging people and advertisers to avoid buying or using flat-faced breeds, and in the UK a similar campaign #breedtobreathe was also launched this year.

However against the seemingly irresistible power of social media influencers, the campaigns have had little traction with pet owners.

Australian Association of Pet Dog Breeders president Kate Schoeffel says what people seem to find endearing on social media is often highly disturbing from a veterinary perspective.

"The online popularity of 'cute' videos of snoring, sleeping sitting up, or suffering from extreme sleep apnoea is alarming as these are all signs of extreme respiratory distress which would be regarded in 'normal' dog breeds as requiring immediate and urgent veterinary attention," she tells the ABC.

The Lassie effect

When Disney movie Finding Nemo became a global smash hit, the demand for clownfish in home aquariums skyrocketed.

It's now estimated that more than 1 million of these fish are removed from the wild each year and in some places they've become locally extinct.

In the mid-1990s people went mad for the movie Babe, the story of a piglet that ends up learning how to herd sheep alongside a family of Border Collies.

Of course, everyone wanted a Border Collie after that, US-based animal behaviour expert Dr Patricia McConnell wrote a few years back.

"This happened in spite of relentless warnings from breeders and experts that Border Collies make lousy pets for most people," she said.

"After Babe came out I saw a lot of clients who had bored, semi-crazy Border Collies."

The RSPCA describes this as the Lassie effect: people see an adorable animal in the media and want their very own.

"It's well known, where [certain] breeds become popularised in pop culture such as movies or TV shows resulting in a spike in numbers," RSPCA's Dr Bronwyn Orr says.

Australian Veterinary Association president Dr Paula Parker says the upside to social media celebrity for animals is that pet owners can play an important role in setting an example for others.

"One of the positive parts of it on social media is that it really highlights the important part their pets play in their life," she says.

"[And they can use] that voice to educate people about some of the challenges these breeds have."