Firstly,Aggressiveness can be defined as the physical or emotional harm to others.
Dogs are aggressive due to the way they are been treated by their owners,
For example>
When a dog is not been give attention, this will make the dog think that he is not useful at all and they might even be aggressive to their owners.
And also,when a dog is been chained all day long, and is not been released for even a minute, this makes the dog to become even more aggressive.
If a dog is not been fed well, this can also make a dog become aggressive, and it might not even be able to recognize its owner.
Productive aggression is when a female dog is pregnant of when it has already given birth to its pups.
When a dog is been prevented form socializing with other dogs or animals is a very common way why dogs get aggressive.
If a dog is ill, it leads to aggressiveness and this is common mostly in dogs,and when they are not been treated earlier enough,they tend to become more aggressive.
I love dogs!