Dogs’ noses are so powerful they can sniff out cheating partners – expert warns

Anna Webb said pooches were able to smell rising stress levels and even pregnancy in their owner, as well as the scent of a secret lover’s perfume.

The dog behavioural specialist said the animal’s curiosity about the smell of a new lover could give the game away through “extra sniffing” or even “avoidance” of their owner.

“The dog could give it away by acting differently towards the human and drawing extra attention to them,” said Anna, who studied with the College of Integrative Veterinary Therapies.

“It could make your partner think ‘Why is Fido sitting over there?’ rather than beside you, or ‘Why is the dog sniffing you a bit extra?’.

“I truly believe the dog could give it away.”

She spoke as a survey by Illicit Encounters – the UK’s largest extramarital dating site – found that an astonishing three quarters of their dog-owning members are “terrified” of their pets giving the game away.

More shockingly, 17% admitted that their dog has led to their relationship ending after their partners became suspicious and investigated further.

Jessica Leoni, the married dating site’s resident sexpert, said: “People say that dogs are man’s best friend but it might not always be the case.

“While they may be loyal, dogs don’t seem to have the poker face to maintain an affair.

“They notice everything and what you see is what you get.

“That may be great for loving couples, but if you’re getting down and dirty with someone on the side, it might give the game away.

“So be warned.”

While our four-legged friends cannot mentally grasp the concept of cheating, Anna said their sense of smell was a “superpower” that allowed them to detect where you had been, who with and even what you had been up to.

It was thanks to the fact dogs have up to 300 million olfactory receptors in their noses, compared to about six million in humans.

They even have a part of their brain dedicated to storing every scent they have ever smelled, called the Jacobson’s organ.

A study at Queen’s University Belfast, published in late-2024, also found pooches were able to smell when the stress hormone cortisol was rising and falling in humans.

It meant dogs pawing about their owner’s business could use their noses to sniff out when they are feeling stressed, according to researchers.

“If you correlate this with having an affair and you come back feeling very happy – or particularly stressed – they are going to pick up this odour and work out your mood,” added Anna, who also co-hosts the podcast Barking at the Moon.

“If you are stressed or lying it is going to raise your cortisol and your dog might look to avoid you. They are definitely picking up changes in your biochemistry because they can smell it.

“For people cheating long-term, they will also start to recognise their smell being consistent over time.”

But it was not just odours that could give disloyal partners away, Anna said. They were also able to detect if something was off through their owner’s facial expressions and postures.

The expert added: “Bearing all of this in mind, I honestly believe there is no reason why they would not be able to sense when you’ve been hanging out with someone new.

“They pick up so much and that is thanks to the really deep connection and bond between humans and their dogs.”

It has not just been the whiff of infidelity that dogs have managed to detect in the past, they have even been used to find cancer.

In 2015, Milton Keynes University approved the trial use of so-called medical dogs to sniff cancer.

The first study, led by Medical Detection Dogs, showed specially trained pooches could detect prostate cancer in urine in 93% of cases.

It was thought dogs could pick up the odour of cancer “volatiles” travelling from the infected cells into urine.

Anna believed there was even more power yet to be harnessed from our four-legged friends, who can also sniff out blood, currency and contraband electronics.

“The truth is, we don’t actually know the total capacity of a dog’s sense of smell – but what we do know is it is remarkable,” she added.