The following question was sent to a listserv for vegetarian activists. Below the question are four replies, two which did not like the idea and two that did.

 Question: Today, another member inquired about buying a membership for the dog who lives with her. Obviously, the dog wouldn't vote and wouldn't be included in official membership figures. I'm thinking of this mainly as a fundraising idea. I wonder if any societies already include members of other species. Thanks.

Reply 1: I do not understand why we need to add other species. If we start with the animal kingdom then we will need to add the plant and mineral kingdoms to membership status to make it equal and to continue with such logic.
We use animals for so many selfish and self gratifying reasons already, Please let's just leave them in peace to live their lives as animals.

Reply 2: With due respect to the dog owner, NO, it is not acceptable even for fund raising. Let us be reasonable and put some reason in rational expectations! A people Society can not be down graded to a level where animals (with due respect to animal lovers and activists) would join members like their owners. Any effort to do so will discredit the Society and will make it a laughing stock of the world out of which it will never be able to come out. If he or she wishes to donate, it can be done in many other ways. I am also sure there are many Societies around the world which will meet the "Animals need to join Societies".

Reply 3: Sorry to disagree with the general tone, but I don't find the idea that  ridiculous. Of course, animals must not have the right to vote, for the very simple reason that they are hardly able to have their opinion or transmit them. And obviously their owners are not entitled to vote for them.
But if their owners are proud to make them members of vegetarian organisations, I definitely see no problem in creating a special class of membership for animals. After all, many societies have honorary membership for "special" members, who often are also not entitled to vote in any issues.
Therefore, I see absolutely no problem in creating a special class of membership for animals in vegetarian organisations. This could be an interesting way to raise funds and also make pet owners happy. The "rights" and "benefits" of these non-human members, as well as the duties, would depend on the resources and goals of each organisation, but I definitely don't think that's so ridiculous.

Reply 4: Your [the author of Reply 2] explanation is understandable. It's not 'what' you said, but 'how' you said it, the words you used, to be more precise: "dog owner", "a people society", "down graded", "animals and their owners", "animal lovers", and so on. This is just a respectful reflection. If we who respect all sentient beings don't change the way we see nonhuman animals, who will?