The same goes for feral animal porn.
Meaning of feral animals (in the r34 sense)
Feral (/ˈfɛrəl/) is a term usually used in furry communities or...bleugh zoophile communities.
It is basically the same as a furry, except just WAY more animal like (By that I mean like, actual animal bodies.)
A few examples of "feral" characters are Balto (Disney), Any of the dogs from 101 Dalmatians, K-9 (Looney Tunes), Astro (The Jetsons), Tod (The Fox And The Hound), Rita (Jungledyret Hugo), and Pluto (Disney).
Basically a "feral" character is just an animal character that is on all fours and acts (maybe not), talks (MANY times not.) and moves like an animal (If it's a Disney or Dingo Pictures animal character, then no.)