Dogs come in all shapes and sizes - the UK Kennel Club recognises 221 different pedigree dogs, from Affenpinscher to Yorkshire Terrier (there are sadly no dog breeds starting with the letter ‘z’!).
Then there are all manner of crossbreeds, from so-called ‘designer dogs’ to lovable mongrels.
Each has its own list of positive and negative attributes, and it’s important to take plenty of time to think about what breed will fit into your lifestyle the best - for instance a smaller dog if you live in a flat, or a hypoallergenic dog if the mere mention of dog hair makes you think about sneezing.
There is even scientific research to guide you, in particular psychologist Stanley Coren’s groundbreaking book The Intelligence of Dogs.
One thing worth considering is that some types of dog are more likely to be aggressive than others.
Before they were domesticated, dogs had to fight for everything from food to territory – so signs of aggression were essential to their survival.
Many of these has been bred out to create the perfect family dogs we know today, but other retain the wilder characteristics.
There can be good reason for this – for example for those used as service or guard dogs – but prospective owners should be aware that this is the case before choosing to welcome a certain dog into their homes.
It should also be said that individual dogs may display attributes that are unusual for their breed, and all dogs have the potential to be aggressive in certain situations.
That said, here are the 20 breeds of dog most and least likely to show signs of aggression.
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17. Basset Hound
It takes serious amounts of energy to be aggressive - reserves that the notoriously lazy Basset Hound will be loath to dip into unless really needed. This also holds true for fellow scenthound extraordinaire the Bloodhound. | Canva/Getty Images
18. Shih Tzu
Some people are suprised that small dogs are often more aggressive than larger dogs - but anybody who has chuckled at a tiny Jack Russell Terrier bullying am enormous Saint Bernard in their local park will attest to the fact. The loving Shih Tzu is an exception to this rule - having a loving and gentle nature. | Canva/Getty Images
19. Whippet
Any energy the Whippet has will be reserved for zooming around the park at high speed - with very little left for anything approaching aggression. When they are done with exercising they are equally happy snoozing on the sofa. The slightly larger Greyhound has a similarly snoozy temperament. | Canva/Getty Images
20. Portuguese Water Dog
Sometimes aggression can be caused due to a lack of understanding so often the most intelligent dogs can be the least aggressive. The Portuguese Water Dog is one such bright spark that has the added bonus of being low-shedding so suitable for allergy sufferers. | Canva/Getty Images