From the Albany Law Journal 21 (Jan.-Jul. 1880):
“In regard to the ownership of live animals, the law has long made a distinction between dogs and cats and other domestic quadrupeds, growing out of the nature of the creatures and the purposes for which they are kept. Beasts which have been thoroughly tamed and are use for burden, or for husbandry, or for food—such as horses, cattle and sheep—are as truly property of intrinsic value, and entitled to the same protection, as any kind of goods. But dogs and cats, even in a state of domestication, never wholly lose their wild natures and distinctive instincts, and are kept either for uses which depend on retaining or calling into action those very natures and instincts, or else for the mere whim or pleasure of the owner; and therefore although man may have such right of property in a dog as to maintain trespass or trover for unlawfully taking or destroying it, yet he was held, in the phrase of the books, to have ‘no absolute or valuable property’ therein which could be subject of a prosecution for larceny at common law….
“And dogs have always been held by the American courts to be entitled to less legal regard and protection than more harmless and useful domestic animals….”
Doubtless, in the jargon of jurisprudence, “protection” of the beast of burden, husbandry, or food has a unique meaning. This is as conceptually awry as saying that the African slave was “protected” under the law from being stolen or killed by the neighboring slave-owner; the “protection” does not inhere to the chattel, but to the owner of the chattel. What’s really unique here is that pet animals were excluded from this (dubious) “protection” because they were conceived of as being too wild to be property—to “never wholly lose their wild natures”—which, alongside their decreasing economic worth as mere pets kept for companionship rather than the Almighty Dollar, disqualified them as “property”—and any “regard and protection” due to property.