Your dog growls? Of course! Its a call to action
"...emeritus professor in animal behaviour...says any unwanted growling at visitors should cause dog owners to be alarmed."
This is a wonderful quote from someone with a distinguished academic background.
Growling is not always unwanted nor unwarranted.
Growling is a part of dog communication and is multi-functional. Just like the vast majority of other language that the canis familiaris has in their repertoire. To lump one form of expression to mean one thing only is not educating the general and average dog owner.
From the same article:
"They (the dog) have no right, if a visitor comes to the house, to even bark once or growl once...That means they feel it's their territory and they (the visitor) are invading it - and then they've got the wrong idea."
This quote is from the same individual in the same article and I hope and pray there is a context that is not included in the primary source.
To be precise:
Offensive or Defensive growling is not an acceptable default communication strategy. Not for the behaviour of growling in itself. Please be aware that the exhibited behaviour indicates the underlying emotional state. That is the root cause, that is what needs to be affected and that cannot be done "in the moment" necessarily.
The home IS their territory?
The visitor IS invading?
They have the RIGHT idea?
The home IS their Territory
Of course it is, how should it not be? They live there, you live there, some others come and go but when the lights go out, who is there all the time? You guys. Its your house, together.
As far as your dog perceives the "home" it is their territory. If we cannot accept that, we should look for another home for your dog.
The visitor IS invading
A visitor enters the house and your not home. How does your dog react? Very likely they will either create space between the visitor and themselves or they will radically decrease the space and protect their home. A select few others will sit idly by. It is up to you to invite people into your house and up to you to facilitate the introduction of the guest towards your dog. That can be as simple as asking for your dog to yield space or to allow a sniff. That depends on your guest, your confidence in your dog and your dog.
They have the RIGHT idea?
There are situations and plenty of them, where your dog has been taught that the guest is undesired. Either through breeding, socialisation, training or situational.
This is very situational and dependent upon the backstory of the genetic and environmental history of your digs life.
Wrap it up!
The main crux is that all behaviour is tied to an emotional state of our dog.
That emotional context determines the specific meaning underlying the expression.
If the expression is alarming, deal with it in the most appropriate way you can at that time.
Investigate the reason for that behaviour and determine:
Was it appropriate
What caused it
Does it need changing
1 of those questions can be answered by you the dog owner, "Does it need changing" the other two are best answered with advice from a professional.
If we continue to deny our dogs innate perspective of the world they live in - which we dominate - how can we best take care of them?
ALL growling is desired. It shows us that our dogs are making conscious decisions to communicate: "This is threatening to me. I need space."
If your dog is growling then please do listen to them!
Give them the space they need and call someone like myself to help you solve this puzzle.
Dogs are not robots. We cannot treat them all the same.