It had many interesting points to make, but my attention was caught by one line that was almost an afterthought, about cats that appear to grieve for companions that die:
"Whether it can truly be evidence of a grieving process as we understand it is debateable...are we merely seeing a withdrawal response to an addictive relationship that has suddenly ended?"
You get this kind of thing quite a lot in pet behaviour books. The writer is aware that they are dealing with a different species with very different behaviours and capacities, does not want to be accused of over-emotional response or projecting human behaviour on an animal, so from time to time during the book, they put on a sort of little virtual scientific tin hat and come out with this sort of thing.
I think it's a bit silly. Do we have some sort of British Standard Grief Unit? Is grief (or joy, or love) measurable in any meaningful sense in human beings? I don't think so.
People react to these emotions very differently, mean different things when they say those words.
Grief is an english language word: of course it's not going to mean exactly the same to me as it does to my non-English-speaking cat, but dressing it up as a 'withdrawal response' - how does that help?
Grief is the word we use to describe that sort of behaviour: it is not a precise word, and it's not suitable for detailed analysis. People grieve for objects, sometimes. If an old man grieves for his dead wife, having not having shown the poor woman any overt affection for the last 20 years, is that not "a withdrawal response to an addictive relationship that has suddenly ended"?
Talking about animals as if they were human beings in little fur suits is not a good idea. But talking about vague human concepts as if they had a precise definition and were consistent across all human cultures and individuals is equally silly, particularly when it's done in the interests of a sort of faux-impartiality.
Actually, while we are at it, almost all animal behaviour books I have read tend to assume that the animal has a 'state of nature', a 'natural' behaviour structure - while totally ignoring the fact that an animal's natural environment is shaped by other inhabitants of the ecosystem. Surely the ecological niche inhabited by the cat or dog is shaped by the fact that they live within a human culture?