In Chinese/Mahayana Buddhism, not only is it possible, but under the Brahma Net Sutra precepts, you are obliged to teach the dharma to all sentient beings including animals.
In that cosmology, hearing the dharma today creates the karma and merit that will bear positive fruit in future lives.
- Failure to Teach Sentient Beings
A disciple of the Buddha should develop a mind of Great Compassion.
Whenever he enters people's homes, villages, cities or towns, and sees
sentient beings, he should say aloud, "You sentient beings should all
take the Three Refuges and receive the Ten [Major Bodhisattva]
Precepts." Should he come across cows, pigs, horses, sheep and other
kinds of animals, he should concentrate and say aloud, "You are now
animals; you should develop the Bodhi Mind." A Bodhisattva, wherever
he goes, be it climbing a mountain, entering a forest, crossing a
river, or walking through a field should help all sentient beings
develop the Bodhi Mind.
If a disciple of the Buddha does not wholeheartedly teach and rescue
sentient beings in such a manner, he commits a secondary offense.
Now from a secular standpoint, this question pivots on if animals are sentient, intelligent and capable of language.
On the topic of sentience, even neurologists don't have a good explanation for why or how human are sentient let alone animals. For those who'd like to think this seal the case that animals are insentient, it doesn't. It means we aren't sure that humans are sentient.
In the area of intelligence and language, there is a mixture of objective evidence that animals are smarter than they look and a lot of people who want to continue to believe that animals are dumb, mindless automatons. It makes it more tenable to continue to eat and exploit them with clear conscience.
On the other hand, while I personally find it plausible that animals have some intelligence, have animal communication systems, it falls short of the tricks humans can do and falls short of human style language.
So no Doctor Doo-little and no chance that an animal, even a chimp could digest something abstract like the tenets of a religion. I do speculate that chimps, whales, dolphins and other social animals probably have an intuitive understanding of ethics.
So finally, I think it is a good project to teach the Dharma to all sentient beings, including animals. It is the heart of my favorite Buddhist vow. It will take kalpas. It will take kalpas to familiarize even a small percent of humans with the dharma. But in kalpas, that's enough time for animals to evolve the intelligence required.
Lets hope we don't exterminate them before that time passes.