Now three years on from the initial COVID-19 lockdown, many pandemic puppies have reached adolescence, the time of their lives when behavioural problems surface.

Nationally many dog shelters have come forward to say they are struggling with an increase of unwanted animals, including controversial breeds such as XL Bullies.

Battersea Old Windsor helps rehome hundreds of cats and dogs each year.

Canine Behaviourist and Welfare Manager at Battersea Old Windsor Rob Bays said: "We know from research that 77 per cent of dogs that were purchased during the pandemic were puppies.

"Given the restrictions in place at this time, many of these dogs may have missed out on important socialisation opportunities to meet new people, children and other dogs.

"Dogs that do not have these early experiences are often more anxious and reactive when faced with novel experiences, which – if not recognised and addressed through training – can risk escalating to more aggressive behaviours."

On top of this, lockdown puppies are also at risk of suffering from separation anxiety.

"Any dog that displays higher levels of reactivity, or separation anxiety, will require more time with our expert behavioural staff and will typically stay longer in our care as we work towards addressing and overcoming these behaviours," Rob added.

Research by Battersea has shown that almost half of people who bought puppies during the lockdown period said that they had not previously considered getting a dog.

It is believed that as restrictions eased, some owners have since come to the realisation that their pet no longer fits into their lifestyle, leading them to give them up.

The RSPCA has revealed the most abandoned dog breads since the start of 2020.

Staffordshire Bull Terriers are the most abandoned, with 4,787 having been given up since the start of the pandemic.

German Shepherds were the second most abandoned, with 1,712 being left behind.

Other breeds being abandoned include the Jack Russell (1,545) and Husky (1,067).

A spokesperson from Dogs Trust Newbury said: "Dogs acquired in lockdown are now reaching adolescence when problems tend to come to a head – so it is feasible that one of the consequences of the lockdown is an increase in undesired behaviours.

“It’s something we need to monitor over time – but also need to keep emphasising to owners to be proactive about any issues arising: it’s never too late to start training your dog; seek help for problems early; know your dog and manage problem situations in the short term; always supervise dogs with children.”

Dogs Trust added that no breed of dog is more likely to be aggressive than another.

“It is important to remember that the majority of dogs in the UK live happy, peaceful lives with their responsible owners. However, in some cases, dogs can represent a danger to members of the public through unwanted behaviours and/or inadequate control and we agree that this needs to be tackled.  

“We also know that aggression is most often a behavioural response to fear, and any breed of dog can act aggressively if they feel worried about something, particularly if they can’t get away from it."