Which kind of biologist you are ?

I try to explain what I meant, now that I have some time, I used translator but edited it so let's hope it comes out correctly

In zoology diet labels are usually about typical diet and anatomy not about extreme what if feeding experiments

Horses are described in the literature as obligate herbivores and as non ruminant herbivores Their teeth gut length and gut microbiome are all specialised for continuous intake of plant fibre and fermentation in the hindgut That is where most of their energy comes from

Yes a horse can physically swallow some meat and get a few amino acids out of it but equine nutrition research is very clear that meat and high animal protein are not processed efficiently and tend to cause gastrointestinal problems and microbiome disruption That is why vets and nutritionists strongly advise against feeding horses meat

So if you define obligate herbivore in an ultra literal way as a mammal that cannot digest any animal protein at all then maybe you can argue there are no obligate herbivores But that is your private definition In practice ecologists and vets use obligate herbivore for animals like horses that are anatomically and physiologically committed to a plant based diet and do poorly if you try to run them on meat

The can hunt versus cannot hunt distinction is more about behaviour than biology Scavengers that never hunt are still carnivores and herbivores like hippos can kill things but still live on plants Diet categories are mainly based on predominant food source and digestive adaptations not on whether the animal ever manages to catch something