An injector device for veterinary use, such as to inject vaccine into the chicken breast muscle. The device includes a finger-held unit connected to a vaccine pumping main unit using a flexible conduit. The operator can quickly start an injection by stroking alongside the breast edge of a grasped chicken, using his fingertips to touch and select the muscle, then start an injection by pressing the finger-held unit against the chicken breast in a designated way. The electric buttons in the finger-held unit may activate a process that actuates a mechanism to inject a hypodermic needle into the chicken's muscle, the pumping system may-then be actuated to pump the vaccine into the muscle through the injected needle.