It’s the sort of viral video that makes you coo. A sweet little creature called a slow loris performs a funny trick. Over and over, a human tickles it. Each time, it instantly raises its arms. How adorable. You watch the video, feel gooey inside, and share it with your friends. But what if you knew that the animal in the video was actually terrified? That it’s raising its arms in self-defence because it hates being tickled, and slow lorises have poisonous glands under their armpits – but it won’t be able to defend itself, because its teeth have been clipped out.

Most domesticated slow lorises have been kidnapped from the wild, packed into a crate and shipped across the planet to become inappropriate pets. The bad news keeps on coming: they could be extinct within five years, and this heartless trade is boosted every time someone clicks the share button on one of those oh-so-cute videos.

Animals of all sorts are become unwitting online stars. Every day there’s a new cute photo or video pinging around Twitter, Instagram and Facebook. But how many of us stop to question the reality behind these pet celebrities?

A viral video earlier this year showed a dog, dressed like a schoolgirl, walking on her hind legs. As the internet cooed over the footage, a separate, graphic video showed the cruelty in how the dog was trained to walk this way.

There are many such stories. A popular video showed a bear in a zoo walking like a human – but didn’t mention that the animal had probably been taught the trick on a cruel “crush” farm. The cute noise a frog makes in a video is actually it screaming out in terror at something just off-camera. Clickbait pages feature geckos and other creatures photographed in poses “that will blow your mind” – but experts believe that string, later edited out, has pulled the creatures into such unlikely postures.

Images of “teacup dogs” go viral, but few know that these dogs’ breeding condemns them to a life of misery. People giggle at the “cats scared of cucumbers” video memes, seemingly more concerned with online reach than the obvious suffering involved. It’s easy to condemn the Instagram star who tattooed her hairless cat, or the tourists who seemingly caused a baby dolphin to die as they passed it round for selfies, but could we ourselves have unwittingly created or shared an image of cruelty?

‘Photos of pets dressed up in costumes are increasingly popular, particularly at Halloween. In 2013 Americans spent $330m on costumes for their furry friends.’ Photograph: Pacific Press/Barcroft Images

Photos of pets dressed up in costumes are increasingly popular, particularly at Halloween. In 2013 Americans spent $330m on costumes for their furry friends. Some pet garments are designed with the wellbeing of the animal in mind and are bought by conscientious owners, but many outfits constrict animals’ breathing, or cover their ears, or make them uncomfortable in other ways. Dogs performing silly tricks or showing meticulous obedience on video have often been not so much trained as drained of life – all so that their owners can earn online brownie points.

That tiger cub you snapped yourself with in Thailand, or the elephant you were filmed riding in India, or the monkey wearing a dress you photographed in Africa, will likely have had a life of misery. The snake charmer you filmed for Facebook will probably have pulled out the serpent’s teeth without painkillers and pierced its venom ducts.

Our awareness of animal suffering evolves. We pat ourselves on the back for taking animals out of circuses. It was obvious they had suffered for our entertainment. But have we moved the problem to the web? Are we blind to the suffering behind many viral hits?

This goes to the heart of the problem with mankind’s relationship with animals. Because they cannot directly speak to us of their discomfort, we deny them the benefit of the doubt. We tell ourselves that the animal on our dinner plate, or at the mercy of the laboratory scientist, was not able to suffer. We tell ourselves that the puppy dressed up as a hotdog, or the cat done up like a pumpkin, found the experience as fun as we did.

So how to tell if a photo is cruel or not? There is nothing so beautiful as nature itself, so any photo that does not involve human interference in animal life is likely to be harmless. To put it another way: taking photos of animals is fine; it’s when we try to stage photos of animals that the trouble begins.

• Chas Newkey-Burden is an author and journalist. He also writes for Shortlist, the Daily Telegraph and Four Four Two