I just called Novaris (Interceptor/Sentinel).
They said do NOT cut it (because it could leave the pet open for infection but maybe they are just saying that) and those are the only dosages available.
The SafeHeart dose which may be good for larger dogs isn't available in the US either.
Maybe I should call Merial (Heartgard) now so I can get the same answer.
Ellie doesn't get the chews. She gets the pills but I bet they will say not to cut them.