Academic and legal discussions around this topic generally focus on two main areas:

In some contexts, dogs are used as a means of control or exploitation in the sex trade. This can manifest in various ways, including:

(PDF) Perturbação Sexual Zoofílica e Ação Legal: relato de caso

: Some sociological studies suggest a correlation between animal cruelty and potential future violence toward humans, particularly children, framing it as a serious public safety concern.

The phrase you used refers to a graphic and explicit subject involving sexual acts between humans and animals (zoophilia).

: Some researchers study the "extreme" porn industry and how such content challenges social norms, moral values, and the human/animal boundary.