So sorry to hear about your cat, my name is ***** ***** I am an experienced small animal veterinary surgeon, I will be very pleased to work with you today and will try my best to answer your question to your satisfaction.
What condition was your cat suffering from?
They said he had fluid on his chest and he was known to have an enlarged heart
I thought that might be the case, the most likely scenario here would have been that the cat was slipping away anyway and the Dimazon was given at that frequency as a last ditch attempt to control things ...
But he was taken to the vets because he wasn't eating. He was being looked after by my neighbours when I was away on holiday
It is true that it is not normally given so frequently though, here is a link to the professional data sheet for this drug LINK
But was the dosage excessive?
OK thanks. He died of a (probable) heart attack. But I suspect stress played a major part in his demise. He had been panting sometimes, but this subsided when he began to relax.