George Orwell of course most famously used animals as a literary device in one of his most well-known works, Animal Farm. However, animals are also a recurrent theme throughout many of his writings, both in his works of fiction and journalism.
Can anyone recommend any sources that discuss how Orwell uses animals in his fiction or non-fiction writing, or how he was influenced by his interest in animals and his rural upbringing? Not just in the most conspicuous example of Animal Farm, but also in his other works, such as Nineteen Eighty-four, Some Thoughts on the Common Toad, Coming up for Air (in which he discusses his love of fishing), his diaries and his essay Why I Write.
Thanks.