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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9. Dachshund
Ask any Dachshund owner and they will confess that their adored pup isn't always the easiest pet to have in the house. Sausage Dogs are notoriously badly behaved and are not averse to turning to snarls, growls and nips if they aren't getting their own way. | Canva/Getty Images
10. Chow Chow
The huge Chow Chow is another dog that should only be considered by experience dog owners. It is a breed that has a dominant personality which can turn to aggression to assert that dominance. | Canva/Getty Images
11. Labrador Retriever
Now we are moving onto the dog breeds with a reputation for being placid. One of the reasons that the Labrador Retriever is the world's most popular dog is its lack of aggression. Vigorous licking of faces is the main thing to look out for with this good natured breed. Most Labs don't have an aggressive bone in their body. | Canva/Getty Images
12. Golden Retriever
What's true of the Labrador Retriever is also usually true of close cousin the Golden Retriever. That's certainly true when it comes to levels of aggression. Other than enjoying a nibble of their owners when teething, this is a dog whose main emotion is love and devotion. | Canva/Getty Images