  Contributions of two-pseudoscalar and vector-pseudoscalar meson loops to the
rho-omega mass splitting are evaluated in a covariant model based on studies of
the Schwinger-Dyson equations of QCD. The role and importance of the different
time orderings of the meson loops is analyzed and compared with those obtained
within time-ordered perturbation theory. It is shown that each meson loop
contributes less than 10% of the bare mass, and decreases as the masses of the
intermediate mesons increase beyond approximately m_rho/2. A mass splitting of
m_omega - m_rho ~= 25 MeV is obtained from the pi pi, K K(bar), omega pi, rho
pi, omega eta, rho eta and K* K channels. The model is then used to determine
the effect of the two-pion loop on the rho-meson electromagnetic form factor.
It is shown that the inclusion of pion loops increases the rho-meson charge
radius by 10%.
