Puppis A is a very famous and extensively studied supernova remnant ( SNR ) that shows strong evidence of shock-cloud interaction .
We re-analyze the GeV \gamma -ray emission of it using seven years Pass 8 data recorded by the Fermi Large Area Telescope ( Fermi-LAT ) .
The morphology of the \gamma -ray emission is more compatible with that of the thermal X-ray and IR emissions than the radio image , which suggests a possible correlation between the gamma-ray emitting region and dense clouds .
The \gamma -ray spectrum in the energy range of 1-500 GeV shows a break at 7.92 \pm 1.91 GeV with the photon indices of 1.81 \pm 0.08 below the break and 2.53 \pm 0.12 above the break , which can naturally explain the lack of TeV \gamma -ray emission from Puppis A .
The multi-wavelength observations favor a hadronic origin for the \gamma -ray emission .