What does the term comrade mean in Orwell's Animal Farm?

In George Orwell's novel Animal Farm, the term comrade is first used by Old Major in his speech defining his philosophy of what would later be called animalism. He calls the animals comrades and urges them to treat each other equally and to work together to overthrow Farmer Jones. He says,

"And among us animals let there be perfect unity, perfect comradeship in the struggle. All men are enemies. All animals are comrades."

The term comrade simply means friend, mate or ally. Its use suggests equality. Rather than using terms such as sir, madam, lord, lady, king or queen, which relate to class or status, the animals are now simply comrades and share everything equally. The term is closely related to the Communist revolution in Russia where the leaders referred to each other as comrades in their struggle to remake Russia into a Communist state like the one first envisioned by Karl Marx. The novel is usually seen as an allegory of the Russian Revolution, so it is fitting that Orwell should have the animals address each other as comrades. By the end, of course, this sense of comradeship is lost as the pigs become just as ruthless, if not more, than the humans in running the day to day activities of the farm. The original ideas of equality are lost and by the last chapter, the term comrade is not mentioned as the pigs change the name of the farm from Animal Farm back to Manor Farm.