One in four puppies sold in Britain are separated from their mother too soon, warns a new study, writes Gregory Kirby.

Vets say it increases the risk of puppies becoming badly behaved and being abandoned by their owners.

One of Britain's most senior vets warned potential owners against buying underage puppies given the chance they will suffer stunted brain development and social skills.

Several UK animal welfare bodies recommend that puppies remain with their mothers for the first eight weeks of their life.

But the latest figure reveals that a quarter of all puppies are now being bought underage, which is "considerably higher" than previously reported, the researchers revealed.

British Veterinary Association president, Daniella Dos Santos, said: "There are very good reasons why puppies shouldn't leave their mother before they're eight weeks old.

"Rehoming from this age means puppies are fully and correctly weaned, and staying with their mother in early development plays a vital role in social and behavioural development."

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Dr Federica Pirrone, from the University of Milan in Italy, added that early separation impairs puppies' early brain development which restricts their ability to adapt to new stimuli and to develop good social skills as adults.

They are also highly likely to exhibit fear and anxiety-related behaviours as adults, which are then often perceived by owners as problematic, Dr Pirrone explained.

She said: "Seeing the mother before buying a puppy enables the prospective owner to ascertain that she is unstressed and free from behavioural problems, which in turn helps predict that the puppy will not develop behavioural problems later in life."

In the UK there are legal restrictions on selling a puppy under eight weeks old, which are reinforced by multiple animal organisations including Animal Welfare Foundation, Blue Cross, PDSA and the Dogs Trust.

Their guidance also recommends that prospective buyers should view the puppy with its mother, and this has been enshrined in English law since 2018.

The researchers wanted to find out what factors were associated with acquiring a puppy at too young an age and without viewing the puppy's mother.

They analysed data for more than 1800 puppies collected from questionnaires completed by their owners between May 2016 and February 2019. The results came from 'Generation Pup', a UK-study on dog health, behaviour, and welfare.

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The responses showed that a quarter of puppies had been acquired before they were eight weeks old, considerably surpassing previous reports.

Just over eight per cent - or one in twelve pups - had been acquired without viewing the puppy's mother.

But only 30 puppies - just over 1.5 per cent - had been acquired under eight weeks of age and without viewing the mother.

The team assessed five factors possibly linked to acquiring an 'under age' puppy.

They found that owners who visited their puppy at least once before purchasing were more likely to take it home too soon.

The researchers said this may be because they could not bear to leave without taking the puppy home, or because they felt the puppy was old enough.

Owners who intended to use their puppy as a working dog, such as for herding animals or pest control, were also more likely to take it home prematurely.

This might be because they wanted to start training the puppy as soon as possible, the researchers explained.

The analysis also revealed that the owner was more likely to acquire their pup prematurely if they already had dogs at home, or if the new dog was a mix of unknown breeds.

Study author Dr Rachel Casey, the behaviour and research lead at Dogs Trust, in the UK, said: "Mixed breed puppies may be more likely to have been bred by a hobby breeder than a licensed breeder, or be a result of accidental mating,"

She added: "Hobby breeders do not need to conform to the same selling restrictions as licensed breeders."

In contrast, the likelihood of acquiring a puppy under the recommended age fell as the level of annual household income rose.

The odds of acquiring a puppy without viewing the mother also decreased when owners visited their puppy before taking it home, bought a puppy registered with the Kennel Club, viewed the puppy's father or collected the puppy from the breeder's home.