First of all, the majority of human communication is language-based. That means it is symbolic in nature, dependent on vocabulary and grammatical structure of some sort, and it can be verbal or written. While humans can and do communicate through body language and scent, these types of communication make up a very small fraction of our net information exchange. Our communication can be about the past, present, or future, and can include abstract ideas and connections.
Most animals do not have the anatomical structure necessary for spoken language, and many species do not appear to have the ability to process symbolic information. Instead, animals generally rely on body language, limited vocal calls, and scent to communicate. As a result, their communications are always in the present tense and are about immediate real-world information such as status, food, territory, and availability to mate.
There are some exceptions to this. A number of primates, including gorillas and chimpanzees, have been taught American sign language, and have subsequently demonstrated basic grasp of symbolic language. Dolphins, which can communicate by sonar, appear to also be capable of symbolism.