  Quantum electrodynamics for $\rho$ mesons is considered. It is shown that, at
tree level, the value of the gyromagnetic ratio of the $\rho^+$ is fixed to 2
in a self-consistent effective quantum field theory. Further, the mixing
parameter of the photon and the neutral vector meson is equal to the ratio of
electromagnetic and strong couplings, leading to the mass difference
$M_{\rho^0}-M_{\rho^\pm}\sim 1 {\rm MeV}$ at tree order.
