Help. dog will die if not fed?

We found this chiuwawa in our back porch. and well shes kind of old and shes afraid. we put flyers up so her owner can find her but noo calls in yet. well thhe problem is i believe she was fed human food. we bought it dog food but does not eat it. she smells it then walks away we even put it in a doggy bowl especially bought for her and nothing. she eats human food lik chicken and meat and fries ? wweird i know. well what can i do?. i dont want to take her to the animal shelter. p.s we cant afford wet food for her either because we have our house cats to feed as well and the cats isnt an issue with the dog because shes not bothered by them helpp