Sorry, I don´t think that - even an italian vet (yes...I know there are such and such) - would miss to check on Clostridium/E.coli....and she isn´t that young anymore, born in 2007...
Stumbling - sure due to heat (inside or outside) is a possibility, that´s why I´ve asked for the wheather
To me it sounds more ...obvious... that there are "dear neighbours" - it wouldn´t be too bad to keep the dogs inside while you are away, just for some time, and check the garden when you come home.
Take care,
koboldine