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.
And one thing you might like to consider is that some dogs are naturally better guard dogs than others.
Labrador Retrievers may be affectionate and popular, but they’re likely to welcome a burglar like a long lost friend - particularly if they come armed with a few tasty sausages.
On the other hand, other breeds are naturally suspicious of strangers, ever-vigilant and have the potential to be ferocious if challenged or confronted. It also helps if they look a bit scary.
Here are the 24 best and worst breeds of guard dog.
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21. Chihuahua
Don't tell the Chihuahua that it's a tiny dog - they THINK they're enormous. Incredibly alert, these cracking watch dogs will be instantly vocal if they feel threatened and can be surprisingly ferocious. This is a dog whose bark is probably as bad as its bite in the right circumstances. | AFP via Getty Images
22. Boxer
One of the best medium-sized guard dog breed, the Boxer was developed in Germany as a hunting dog. Boxers take two things very seriously - protecting their beloved family/pack and making sure they get a good play every day. | Canva/Getty Images
23. Boston Terrier
Another breed that proves great guard dogs come in all shapes and sizes is the scrappy Boston Terrier. These charmers are pretty much made of muscle and used to be used in dogfighting during less gentle times. Known as 'the American gentleman' due to their friendly personality, they'll be anything but gentle when it comes to protecting their territory. | AFP via Getty Images
24. Staffordshire Bull Terrier
Britain loves a Staffy - they constantly feature in lists of the country's most popular dogs. Another breed originally bred to fight they now make brave, compact, muscular and tenacious guard dogs. They are also incredibly loyal and loving - but if they bite then they'll not be letting go in a hurry. | Getty Images