Rainwater's "Encyclopedia of American Silver Manufacturers" shows this mark as unascribed or unidentified. I didn't find it either, but I might be able to offer a possible lead.
In a couple of my Canadian books they show the following mark among many International Silver Company marks. Apparently International had branches or factories in Canada. No other information is given. Although it's not the same mark as yours, it's the only other bulldog mark I've come accross.
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Regards,
Pat.