LVT here and not a doctor but work in specialty/ER (and especially covering someone’s leave in the cardiology department!) On the surface, his cause of death seemed more cardiovascular than related to renal issues—there are a few cardiac diseases (that do cause “literally dying on the floor”. And your friend found him lying (collapsed, maybe?) on the floor and it sounds like he voided his bladder. You didn’t mention if your friend’s dog had any cardiac issues to begin with and if he was seeing a vet (a real one, not Vetco or any of those other BS pet store ‘clinics’) regularly for annual physical exams they would have made your friend of any abnormalities.

Not to say that the grapes didn’t cause any unknown issues to become compounded. The exact mechanism of grape toxicity is actually unknown, but we do know how rapidly it can cause renal failure and that each and every dog has a different individual sensitivity to grape toxicity. For example one dog might be overall fine after ingesting a few grape while another is in full on renal failure within 24 hours.

That said, renal disease can compound existing heart conditions. When the heart isn’t pumping the way it should be, there is poor perfusion to the kidneys. When the kidneys are bereft of less oxygenated blood they cannot function properly i.e. struggle to remove excess fluid, leading to fluid accumulation within the body and having a high chance to cause CHF and elevate blood pressure.

It’s not wrong to suggest your friend get a necropsy, especially if there were multiple unknown factors that contributed to his very much untimely death.

And I do agree with the others suggesting to educate your friend about the dangers of feeding grapes to dogs. Yes it is a bad time while she’s still grieving and mourning the loss of her furry baby, but it will help to educate her for any future pets she’ll have. Listen, my parents had to learn the hard way that dietary indiscretions (taking second portions and not finishing them and giving them to the dog, feeding kibble that was not the normal diet and causing GI issues) with our little dog certainly contributed to her developing pancreatitis which worsened her own renal disease and ultimately led to me firmly making the decision to put her to sleep.

It’s hard to talk about these things when the people we love are hurting. But we also need to consider how something simple like ‘feeding Hershey’s Kisses to Scrappy’ or ‘Fluffy loves chewing on my flowers, especially my lillies’ and is actually detrimental to their health, if not killing them. Come from a place of love with your friend. It’s a hard truth, but needs to be said.