At a minimum, veterinarians recommend that K-9 handlers carry a first-aid kit, learn how to give injections, and know how to administer oxygen. A brief session with your veterinarian or even a vet tech should be sufficient to learn how to correctly give injections. Here are some photos to illustrate proper first-aid techniques.
For more information about first aid that handlers should know, read the POLICE Magazine article K-9 First-Aid Kit Basics.