could also be the size of the needle, maybe? For interferon I think they use the same needle they use for diabetes... very, VERY sharp and small. Although - I did notice some needles weren't as finely honed as others.. almost barbed, and those hurt like heck. If the rabies medicine is thick they may have to use a bigger needle.

Funny aside: Everybody wants to experience giving someone a shot at least once in their life, right? Ok.. probably not, that could just be me.... when I was on the Interferon one of my daughters game me shot once... just to experience it.. my other daughter wouldn't even think about it. My wife LOVED giving me the shot.... volunteered every shot. But then, I think she just gets a kick out of seeing me in pain.