Paper I missed from a couple months ago in the Journal of Archaeological Science: Burying key evidence: the social bond between dogs and people (Volume 33, Issue 2 , February 2006, Pages 158-175), by Darcy F. Morey. Abstract:
People have been burying or otherwise ritually disposing of dead dogs for a long time. They sometimes treat other animals in such a fashion, but not nearly as often as dogs. This presentation documents the consistent and worldwide distribution of this practice over about the past 12,000–14,000 years. Such practices directly reflect the domestic relationship between people and dogs, and speak rather directly to the timing of canid domestication. In doing so, they contradict recent genetics-based inferences, thus calling into question the legitimacy of focusing mostly on genetic factors as opposed to other factors. This discussion seeks to work towards a sound framework for analyzing and thus understanding the social compatibility between people and dogs. That compatibility is directly signified by the burial of dogs, with people often responding to the deaths of individual dogs much as they usually respond to the death of a family member. Moreover, that special social relationship continues, as illustrated clearly by the establishment, maintenance, and ongoing use of several modern dog cemeteries, in different countries of the world.
It's basically a survey of dog burials throughout the world, which are surprisingly common. Morey notes that Ashkelon in modern Israel contained a separate cemetery wherein over a thousand dogs were buried. The paper carries some good insights into the motivations behind dog burials and what they mean. After the review of various dog burials, he gets down to some interpretations. First, that there is true friendship between the species which is indicated by the care with which dogs are usually buried. That is, they're not just tossed into a ditch, they're carfully placed -- posed, if you will -- into purposefully dug graves. He describes one case where the dog was very elderly and suffering from a range of maladies resulting from both injury and old age and therefore could not have survived as long as it did without intense human care.
Second, the quote above come from the section describing the special status of dogs as being something not quite on par with a human 'person', but not just a utilitarian 'beast' either. There are people, there are beasts, and there are dogs. (And some might argue, there are cats wryly observing all) As morey puts it:
Overall, in being granted ritualistic treatment at death, living dogs had a special status, well encapsulated by James Serpell who referred to them as “neither person nor beast” [144(p. 254)]. This compelling characterization was used by Radovanoviç  as part of the title for her discussion of certain Mesolithic dog burials in Europe's Iron gates region (dating to ca. 9500–8500 B.P.). It would seem that to those people, people were people, beasts were beasts, and dogs were dogs, something qualitatively different from either people or beasts. Mark Derr, exploring the modern relationship between people and dogs, put the matter this way: “Dogs cannot be slaves or children or royalty. They can only be dogs”.
Obviously (?) the fact that these animals were interred in this way -- and often in the company of a person -- indicates that the people had some concept of a dog spirit that would carry on into the next world as well. This seems superficially similar to the Egyptian mode of burying people with foodstuffs, but in those cases it was usually only parts of various food animals, not the whole thing. Hence, while a mutton leg doesn't indicate any sort of continuing relationship beyond the grave, vis a vis the person and the sheep, dog burials suggest that some essence of the dog and its personality would, in fact, continue on and interact with its owner.
If you're a pet owner, you might be distressed to know that, apart from the rare occasions where some event sent the owner and dog into the afterlife together, the dog was no doubt killed outright in order to accompany the deceased. And you don't want to know how all those cats got mummified in Egypt either.
The remainder of the paper deals with the earliest indications of domestication and the sorts of utilitarian uses dogs might have been used for. Morey concludes:
People can and do bury their deceased dogs in cemetery areas, and they have done that for thousands of years. In doing so, they are burying key evidence concerning the development of the social relationship between dogs and people. But they are burying it in a way that allows us to find it and describe it. We may not fully understand its basis, but because it exists, we know we have bonded with the animals, and as a result of that relationship, we often treat dogs in death just as we treat people in death.