I have the choice of Pedigree(Thailand), CHUM(Australia) or Waitrose(UK) of canned wet dog food. Which is more trustable? and these are my only options, pretty backward country where dogs aren't favoured.

And how do I properly prepare the above food with additional dry biscuits prescribed by my vet?

*It is for a 7 month old maltese/shih tzu and a 10+ yr senior pure maltese

choose waitrose, it's organic.

If you have access to a grocer or butcher you should consider a raw diet. It's 500% better than that canned crap.

Wet food isn't very good for your pet. Do you have access to Purina or Friskies brands? Those are the only ones I trust.

If you only have those options I would choose waitrose.