Or not - China is the biggest exporter of leather, and get through an average of 2 million cats and dogs to produce it as you can't tell the difference anyway. And in that case is the primary source then, any meat is a byproduct.
And even without that, the opposite, if you don't buy leather it will reduce the value of leather and reduce the value in killing cows.
I am not vegan, or even vegetarian, but if there is a choice where both options are as good, I will go for the vegan option.