Theologians cautioned that Francis had spoken casually, not made a doctrinal statement.

The Rev. James Martin, a Jesuit priest and editor at large of America, the Catholic magazine, said he believed that Francis was at least asserting that “God loves and Christ redeems all of creation,” even though conservative theologians have said paradise is not for animals.

The question of whether animals go to heaven has been debated for much of the church’s history. Pope Pius IX, who led the church from 1846 to 1878, longer than any other pope, strongly supported the doctrine that dogs and other animals have no consciousness. He even sought to thwart the founding of an Italian chapter of the Society for the Prevention of Cruelty to Animals.

Pope John Paul II appeared to reverse Pius in 1990 when he proclaimed that animals do have souls and are “as near to God as men are.” But the Vatican did not widely publicize his assertion, perhaps because it so directly contradicted Pius, who was the first to declare the doctrine of papal infallibility in 1854.

John Paul’s successor, Benedict, seemed to emphatically reject his view in a 2008 sermon in which he asserted that when an animal dies, it “just means the end of existence on earth.”

Ms. Gutleben of the Humane Society said Francis’ apparent reversal of Benedict’s view could be enormous. “If the pope did mean that all animals go to heaven, then the implication is that animals have a soul,” she said. “And if that’s true, then we ought to seriously consider how we treat them. We have to admit that these are sentient beings, and they mean something to God.”

Sarah Withrow King, director of Christian outreach and engagement at PETA, one of the most activist anti-slaughterhouse groups, said the pope’s remarks vindicated the biblical portrayal of heaven as peaceful and loving, and could influence eating habits, moving Catholics away from consuming meat — which she asserted had already been happening anyway. “It’s a vegan world, life over death and peace between species,” she said. “I’m not a Catholic historian, but PETA’s motto is that animals aren’t ours, and Christians agree. Animals aren’t ours, they’re God’s.”

Whether the pope’s remarks will prove to be a persuasive new reason not to eat meat, a potentially worrisome development to the multibillion-dollar beef, pork, poultry and seafood industries, remains unclear at best. But they did cause discussion.