As some of you may know I adopted a 10 year old Tri Can called Charlie at the end of May. Charlie has been fantastic and my wife and I have really fallen in love with him over the short time we have had him.
When we got him he had quite a severe heart murmur and was a little chunky monkey so we put him on senior food and controlled his weight.
Recently Charlie has had no interest in his own food but will beg for ours. We put this down to him being a fussy bugger so we tried him on a different brand his previous owner used to give him. He ate this for a couple of days but then would turn his nose up at it. His weight has fallen from 11.5kg to 9.5kg which is alarming.
In the last week he has became very lethargic which at first we put down to him not eating enough so we gave him boiled chicken and rice with vegetables. He would eat it for a day or so but then nothing unless we hand fed him.
Yesterday however he had diarrhoea which was strange for him as he has never been the best pooer. He would struggle to do a couple of pencil thin stools. The vet checked him and said he was ok though. The diarrhoea was green water and very mucusey. He was also vomiting up all he had been hand fed.

We took him to the vets last night and they told us it might be cancer. They gave him an antibiotic injection, an anti-diarrhoea injection and some Noroclav. They told us to see how he was over the weekend and if he was no better they would begin the tests on Monday.
When we adopted him we were told that when he was castrated they found a lump which they removed at the same time but it was benign. I have contacted the rescue to see if they have the test results to see what he was tested for at when they found the lump. The vet said depending on what they tested for cancer is less likely if he was given an all clear but not impossible and we should prepare for the worst.

Charlie is a bit brighter today and did eat his breakfast. He is still a bit lethargic but he is an older dog with a murmur so it's to be expected. It's the other symptoms I'm worried about.

Does anybody have any thoughts what his symptoms may be other than cancer? Also what advice can you give me regarding caring for a dog with cancer. What treatment are they given, how quickly can it develop (he was clear in May), what do I need to do to care for him, what is the prognosis/success rate, what can I do to help prevent my other dogs from getting it, what is the cost of treatment etc etc.

Any advice would be gratefully received.