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 24 breeds of dog most and least likely to show signs of aggression.
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21. Newfoundland
The huge Newfoundland is the very definition of a gentle giant. Their lack of aggression means that they are known as 'nanny dogs' due to their gentle nature and the fact that they get on so well with young children. | Getty Images
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22. Beagle
They can often be mischievous, noisy and boisterous - even thoroughly badly behaved - but the Beagle is rarely aggressively. | Getty Images
23. Bulldog
Both the English Bulldog and the smaller French Bulldog tend to be fairly peaceable breeds - they actually have very powerful jaws but are unlikely to use them for anything more harmful than chewing a favourite stick. | AFP via Getty Images
24. 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. | Getty Images