Legacy Interactive games has two great games for the Nintendo DS, and they're fun for the animal lover in your family.
Zoo Vet: Endangered Animals is a great interactive game where you get to be the animal doc. We got a copy to try out and I was excited to get it since my middle child is a real animal lover.
The first thing I noticed was the fabulous graphics! The animals are beautiful. The second thing I noticed is that the vet cases are quite realistic, they don't have imaginary illnesses or injuries. My 12 year old son learned things right away when he started playing.
You can do things like stitch up a wound, give medicine or an injection depending on your patient's symptoms and clues. There's always assistance, you have co-workers, and there's some fun, too as there are several smaller games you can play with the vet's equipment.
It took a little practice to learn how to use the tools, where to touch the stylus, etc., but my kids have really enjoyed this game.

We also got to try out Pet Pals: Animal Doctor for Wii. This is another type of veterinarian simulation game. In this one, the Wii controller simulates the vet's equipment and you can treat your patients in surgery, take care of injuries and other conditions and you can even feed and play with your charges in the recovery room to help them get better quickly.
As with Zoo Vet, these cases are true to life and there's lots to be learned and there's help by your side as you play.
This one took a bit of practice with the controller, if your kids are younger (It's meant for ages 10 and above), you might want to try to figure out how to play the game yourself before you let them have a crack at it.
These are both great games for kids who love animals. I really enjoyed the real life scenarios and how my son learned a few things right off the bat. Check them out, they'd make fun Easter basket goodies!