While the following will be quite obvious to many people, I think it never hurts to reiterate the arguments for our stance. So what will follow is the case for anti-racist policies within the movement. It's going to be quite a long post but I hope you will read it through and let me know what you think in the comments.
The Pragmatic Case
In terms of the advancement of non-human animal rights alone (without bringing any 'human rights' aspect in to it) there is a very strong case for an anti-racist stance within the movement. Most obviously, racism means that potential new activists and vegans can be turned off to the message if they feel there are people that hate their race hanging around. No one wants to join a group with members that hate you for an aspect of you that you can never change! The animals will suffer because certain communities will feel excluded.
Perhaps slightly less obviously, having racists in the movement will effect the movements expansion in general. Activists from other movements are perfect new animal activists. They have already shown they are motivated enough to turn up for demos and clearly are concern about the world around them. We should encourage cross-movement solidarity. People from human rights causes will be put off animal rights if the movement is seen to harbour racists. Additionally, most good people (who are the sort of people that would care about non-human animals) will be put off by any racists lurking around. By putting them off we would be only harming the animals.
If animal rights does not transcend colour, religion and national origin the animals, to put it bluntly, are stuffed! On the other hand if a few racists feel put out about being made unwelcome in animal rights there is not going to be a big problem for the animals. So the pragmatic animal rights stance against racism alone make sense for the animals.
The Ideological Argument
Animal rights is based on the principle that irrelevant characteristic should not be used to preclude individual rights. Quite simply a being deserves rights because he or she can suffer and otherwise experience life. The fact such a being has four legs or two has no bearing on whether their interests should be taken into account.
This basic logic rests upon an acceptance that picking characteristics at random (such as species) is not an acceptable way of drawing a moral line. It also rejects the idea that one can choose only to protect his or her own group and exclude others.
Racism is a morally irrelevant characteristic just like species. Races are groups of people and are not significantly genetically distinct. Therefore they do not have a specific way of behaving, each individual is different. They all can suffer and experience life, which is the basis for animal rights. Therefore the very logical pillar on which animal rights stands precludes racism.
It Is An Animal Rights Issue
But we can go further. Animal rights at it's most basic level is an understanding that all sentient animals have rights. To discriminate against a species is speciesism. Humans are just another species of animal. To discriminate against humans (or a group thereof) is a direct form of speciesism. We would not allow discrimination against one type of cat because they came from a certain country so to allow an analogous form of discrimination against human animals is clearly speciesist.
This is not a flippant point or a question of semantics it is something at the very core of animal rights that discrimination based on species membership is unacceptable. Therefore racism is specifically a breach of animal rights. It is an animal rights issue. Clearly the animal rights movement shouldn't support actions that breach the rights of animals, that would make no sense!