The video –posted by fellow train passenger Roxy Huang to youtube – the woman is seen repeatedly hitting and even biting her small dog.
'Stop it now you hear me,’ the woman says to the frightened animal, whilst continuing to hit it.
Despite the dog trying to escape her clutches the woman keeps yanking it back by its leash.
A fellow train passenger tries to intervene, saying: 'You gotta stop hitting your dog.'
The dog owner responds, 'Pardon?' then quickly becomes defensive. 'Who are you? What the f**k are you talking about?'
Another passenger is heard complaining to a Toronto Transit worker 'She keeps biting its tail.'
While it has not been confirmed, Roxy says she suspects the woman may be on drugs.
'The whole train stopped, more than three TTC staff walked to her and then she got off the train. Someone like her should never own a dog or a pet,’ she explained.
Watch the disturbing video below: