But they don't stop at guarding my household, no, they guard the neighbours' homes as well.
My chihuahuas will let everyone know that the meter reader is in the street, a courier has pulled up two houses down, the folk across the road have visitors and someone has pulled over by the tree down the road to make a phone call. You're all very welcome.
They will also announce to the entire neighbourhood that someone is walking past, cycling past, running past or sneaking down the road wearing a balaclava and carrying a bag of breaking and entering tools.
The dogs won't tell you which though, so you have to get up and go out and look. So far, almost all of the times, it's someone perfectly innocent. But you never know do you?
One of the dogs used to let us know if a car was going past. And for good measure he used to chase all the cars away just in case they were full of bad guys.
It took him a lot of time and energy chasing all those cars up and down the fenceline, given we are on a busy state highway, and he had also tasked himself with keeping all the sparrows off the property.
He wore out after a bit, but by then he thought his name was "Shut up Jake" and it took a long time before he would respond to just Jake.
He then took over surveillance of our immediate neighbours' driveways, to the extent that he would stand on one neighbour's lawn and shout at anyone he thought shouldn't be there. This, often, included the neighbours themselves. Which was, to say the least, embarrassing.
Jake has finally shut up (well, he may still be barking but if so it's in heaven and the gates must be soundproofed). So his son, Mungo, has had to take on Neighbourhood Watch duties.
Mungo is very conscientious. He takes the traffic watch seriously, keeps on top of the bird threat, does a regular round of one neighbour's back lawn to shout at their dog (probably accusing it of incompetence) and always escorts us if we pop over to see the other adjacent neighbours because he thinks their cat is dodgy.
On top of all that, Mungo has had to take on extra responsibilities because the council has facilitated the building of a cycling and walking track on the river reserve a mere 200m or so from our house.
This is patently well within the territory of even the smallest chihuahua.
Mungo was outraged when he realised people were promenading to and fro on the river reserve. He has been outraged for about 18 months now and shows no sign of calming down. I fear for his blood pressure.
He has even had to take on an assistant, Hugo, to help him patrol the area and take over swearing at the invaders when his voice gets tired.
As yet Hugo is struggling to be taken seriously, as he is extremely small and I think people wonder why a guinea pig is barking at them.
He needs to get up to speed though, as in the meantime the matriarch of the chihuahua horde, Bunnie, has put herself into retirement.
After a lifetime of telling on chooks in the garden, goats in the grapevine and motorists pulling over so their passengers can be carsick in the ditch across the road (thanks Bunnie I needed to see that), she's now decided the only things to be barked about are the cat stealing her spot on the couch or her owners if we have omitted to carry her to the bedroom and put her on the end of the bed at lights-out-time.
I'd say it was more peaceful without her input, but she's taken up snoring instead.
At least the neighbours can't hear that.