The protagonist used to have two dogs, who don't appear in the story but died before the start of the book. [SPOILERS] We eventually learn that the dogs were killed. The person(s) who killed them do get their comeuppance.
The main character is sad about her dogs which she lost before the start of the book. She sometimes refers to them as "my little girls" and you might think she's talking about children who died, but she's not.
The narrator uses the phrase “testosterone autism” to reference the behavior of aging cis men, and to generalize behaviors seen as stereotypically “autistic”. Interest in trains and world war 2, social ineptitude and cruelty to name two.
The phrase “testosterone autism” is used to refer to negative traits of cisgender men.
The narrator is referred to as “crazy” and “mad” in negative, dismissive ways throughout.
Been a while since I read this book, but there's a series of murders and I think at least one of the victims was a father of adult children. It's not focused on too much and isn't intended as particularly tragic.
A scientist character is studying a rare species of beetle, and there are descriptions of the beetles' life cycle etc. A dead body is found covered in beetles.