I dont see it here, so figured someone's gotta post it. Here is the definition of veganism as made by the vegan society circa 1944:
"Veganism is a philosophy and way of living which seeks to exclude—as far as is possible and practicable—all forms of exploitation of, and cruelty to, animals for food, clothing or any other purpose; and by extension, promotes the development and use of animal-free alternatives for the benefit of animals, humans and the environment. In dietary terms it denotes the practice of dispensing with all products derived wholly or partly from animals."
It is not a great definition in my opinion. The sentence "as far as is possible and practicable" is too vague. It makes people claim that when it is merely very inconvenient to get a vegan meal, it is vegan to eat something with animal products.
In my opinion veganism should be the extention of human rights to animals. That would mean that even killing a pig for a heart valve to safe a human would not be vegan. After all, we wouldn't even kill one human to safe multiple others in a similar scenario because that would violate the rights of the to be killed individual. You could argue that it is better to safe more lives, sure. But it wouldn't be the 'pro-human rights' thing to do.
I believe that is more in line with the philosophy the vegan society was founded to promote than their own current definition.
I think that line is important to explain that its impossible to completely wash our hands of any animal suffering, even as vegans, but I agree with your points that animals should given better rights (the first page or so of "animal liberation" by peter singer explains why the term "equal rights" is kind of unnecessary, but I know what you mean)