You can rule out a DFC or any other gong.
When he retired wef 6 March 1945, the Canada Gazette listed him:
https://recherche-collection-search...._p00001_z04843
Go to page 21 of 128, left hand column - you'll have to excuse the LAC for the terrible scan job - and scroll down to "T/F/L A.H. McDonald" Notice any gongs listed next to his name? Go one up to J16989 Charles Parkinson McDonald and you'll see
DFC and
DFM.
Having looked at his political career (1956 - 1980) in the Regina and Ottawa newspapers, there is never a time where a gong is mentioned.