Ethical Animals
Q. Why doesn't Jewish law allow people to be buried together with their animal companions? Don't animals also have a soul?
A. Your question is a profound one. We can arrive at a partial answer by a careful examination of the various sources relating to animals.
Let's start with the Bible. On the one hand, the Torah clearly distinguishes man from the animals, and explicitly states that man only was created in the Divine image, and that man was given dominion over the animals. (Genesis 1:26.)
On the other hand, the command to give rest to our beasts on Shabbat (Exodus 20:9) suggests that they are capable of appreciating their rest and enjoying the Shabbat on their own level. And the Prophets suggest that beasts are capable of ethical perfection, for Isaiah prophesies that in the time of the complete future Redemption, predatory animals will lose their aggressive character: "The wolf shall dwell with the lamb; and the leopard shall lie down with the kid, and the calf and the lion and the fattened lamb together; and a small lad shall lead them." (Isaiah 11:6.)
Many statements from our Sages support the idea that a certain level of righteousness is relevant to animals. For instance, Rashi explains that the animals (except for those in the Ark) were punished together with mankind in the flood because they also sinned. And in a few places the Talmud states that animals belonging to very righteous people are themselves impervious to sin.
In Judaism, our relationship to animals is defined by this dialectic or tension: on the one hand, the importance of recognizing their special worth; on the other hand, the importance of acknowledging the unique spiritual level which distinguishes man from the beasts.
For example, it is a mitzvah both to help unload an overloaded beast as well as to help someone load his beast of burden. Normally the first mitzvah has precedence, emphasizing the special importance of animals and the mandate to reduce their suffering. But when there is a question of human dignity involved, then loading takes precedence, emphasizing the primacy of humans.
Another example: As we just mentioned, Rashi explains that the flood punished animals because they too have moral obligations at a certain level. Yet the same commentary brings another explanation: that animals are meant to serve man, and when man is destroyed the animals have lost their reason for existence.
This same tension exists in mourning. On the one hand, the Shulchan Aruch (authoritative Code of Jewish Law) does contain a formula for comforting someone who has lost a beloved animal ("HaMakom yemalei chesroncha" - may the Eternal fill your loss); at the same time, the Shulchan Aruch forbids us from comforting someone who has lost an animal in the same way we would do for someone who is bereaved of a relative.
The same principle can be applied to burial. While there is nothing wrong with acknowledging an animal's worth by giving it a burial, we still have to accord special acknowledgment to mankind's unique spiritual level, and avoid burying people together with beasts.
SOURCES: Genesis 6:7 and Rashi's commentary; Babylonian Talmud, Yevamot 99b and Ketubot 28b; Shulchan Aruch, Yoreh Deah 377:1, Choshen Mishpat 272:10; Igrot Rayah of Rav Kook, number 90.