It has been brought to my attention that, at the moment, pets are not easily identifiable as EchoPet entities. The only way to achieve this is to unnecessarily traverse through OBC/NMS (as is currently done in the plugin itself):

if (((CraftEntity) entity).getHandle() instanceof IEntityPet) {
    // do stuff
}

Potential solution(s):

1. Label each pet entity with a specific metadata tag.
2. Provide a better API (EchoPet.isPet(entity)?).
3. Other solutions.

Option 2 has the disadvantage of requiring plugins wishing to detect if an entity is a pet to explicitly (soft-)depend on EchoPet.

I'd vote for #1, like Citizens does :)

A simple "pet" boolean would be great. I currently look for unknown entity types, but we also use MythicMobs and they are using custom entities in the latest version. I want to be able to target mobs but not pets, so it's a bit of an issue.