Various brands of heartworm pill are different. Some are given whole as tablets, some are soluble for dogs that will not take tablets and some are chewable. Crushing tablets is merely a way to encourage dogs that refuse tablets to take their medicine.

Interceptor is a chewable heartworm pill so no need to crush unless they are likely to swallow it in one, in which case you could break them up to make sure the dog eats them a little more slowly.