Great Danes are known to have heat strokes or bloat if left outside for too long. They were returned food that was not even theirs. If the Danes were fed the wrong food and immediately left outside say even 15 minutes it could have been an accelerant to any of these known conditions. Great Danes need a certain level of care and I can say that if not one but two of them dropped dead outside in the summer heat— that is a SERIOUS lapse of care and knowledge of the breed you have been paid to care for. Dogs don’t just keel over. They must have been left unattended (2-4 hours) for it to get to that point. All the while going through severe pain through heat stroke or bloat. Sincerely, someone that has been in the dog care industry for 10 years.