You can incorporate you love of animals into your answer. You can say that, because you have loved animals you whole life, you want to be a vet tech to help them heal. That you want to not only be able to help the animals, but also to help the people who own the pets understand and care for them better.

I know he said not to say "because I love animals" - but that's probably what everyone says, and it's not a complete answer!

Talk about what you hope to learn, and mention helping people help their animals, as well as assisting the veterinarian in caring for the critters. If you want, mention that improving the health and well-being of pets is important for the community, that elders with pets live longer, happier lives, but may need extra help caring for them ...