Great question and I would start by saying all dogs can bite. Most people do get surprised when they hear that all dogs can bite
As with many questions with behavior the answer is always “It Depends”.
The way I look at it is every dog has a bite threshold which will be related to trigger stacking. Much more is involved but the short answer will be yes. I’ll try to give some brief thoughts on this topic.
Most bites in my experience are from Dogs that suffer from fear and anxiety. Think of Dogs that are over aroused say from a door bell and we touch the dog after the bell rang and the dog just turns and bites. Many will label that as redirected aggression which is very common. Most owners in my experience will get bitten from redirects.
Now if we have a dog that has fear and or anxiety towards certain triggers like unfamiliar people, bikes, children and all three happen at once the dogs bite threshold be lowered and have a good chance to bite.
In your case we would have to get more info on the dogs history by asking lots of questions to look for red flags and possibly function of the behavior/body language we observed when your friend came home eg.. lunging, barking and body language they observed.
Questions like:
How old is dog?
How long you had the dog?
Does your dog have any fear towards certain things? Eg. Unfamiliar humans, dogs....
Is this a new behavior your observing?(related to how long they have the dog)
We would need a history report to understand why this dog barked or even what type of barking it was when they came home eg. Excitement, startled, unsure, fear , anxiety.....what happened after you entered?
Short answer will be yes and in my experience it usually happens with dogs that are new or been in the home for a month to a few months. Usually many red flags where missed.
Hope this helps some and makes soem sense
