They are not (regarding the topic title).
It's just that those participating (either "being able to" by lingual, technical or social ways or "being interested and find time for participating" by their ways of life) in forums like this one are rarely those which live in smaller communities with well-accepted sexual ways of "growing up" - as for those the ways of life are common all-day scenarios, while Internet access and mobile technology features are not.
As such: why should they use (if possible at all) the later ones to communicate their established cultural standards?
There are several smaller and partly bigger communities as example in Africa, Latin America and even some mostly Muslim countries in the middle east, which handle sexual relationships between young men and some animals (donkeys being one of the loved characteristic animal in recent years media coverage stories, while there is proof of pigs, horses, camels, goats (quite often, I have to say..) and probably even dogs available) and sometimes got those even medially covered by reporters (mostly out of first world countries), be it as an amusing fact or a sidestory - sometimes even as the main topic they circle their insight coverage around.
Interestingly sheep are falling low in media coverage from my own media sightings. Doesn't have to resemble reality, tho.
It's just not "a community which loves to fuck animals" for the west / east. Mostly it resembles quite primitive living styles with nonetheless happy people, which as example have a way to "learn how to please women" by copulating or stimulating with animals in their young (adult) years. And probably older people participate as well, who knows - but nobody cares. It's not the main topic of local interests. It's just one shard of a slice of lives.
As such surely you won't find many of those communities participating in online forums circulating this specific set of topics.
Addendum: It's well possible that women are participating as well, but as it is mostly in such rural communities, they don't talk or joke that much about those aspects of life. And some social standards established there might limit the freedom of women somewhat (as it is given in Muslim countries still to this day) and the men / boys will cover most of the commenting concept of such media takes.
Addendum #2: Funnily enough I've not yet met anyone out of western countries which would feel "shocked or enraged" by such coverage and details. Maybe because it's easy to "blame it at the primitive living styles over there"? No idea what's the reason but it mostly causes jokes, amusement and laughter, not hate or despising insults.
Would be great if people could act the same if "locals" to them (means: their family, coworkers, friends, known people) enjoyed intimate relationships to animals on a comparable respectful level. But that's a far-fetched dream.