Hey there,
I have been trying to look up the study itself. I can Google and find lots of people who quote the study, but I am not sure what the study was called. I know they say that it was a 2005 Purdue University Study.
I know that they gave the dogs a quarter of a cup of raw leafy green and yellow/orange vegetables 3 times per week and the Cancer rate dropped by 90%. If you can get your dog to eat them every day, it can help. Also, cruciferous veggies.
There have also been studies with active cancer where adding in vegetables slowed the rate of cancer growth.
https://www.ncbi.nlm.nih.gov/pubmed/16013542 As far as handling it dietarily, it depends on what your dog will eat. I took my dog vegan whole food plant based on Bacon The Vegan Dog on-line whose owner healed him from a big tumor just changing him to vegan. I did the no oil, vegan, based on what people like Dr. McDougall said. Oil speeds up Cancer. Cancer needs growth hormone to spread. Getting the animal products to about 5% of the calories causes it to go dormant. (The China Study and Healing Cancer from the Inside Out.)
For me, the choices were doing it this way or doing it KetoPet Sanctuary way. They have a link to Valiant foods, but it is Keto highest fat possible. About $250 per month and you add in their food with oil. 90% oil and my dog doesn't like oil enough to get him to eat that way anyway. They do have footage that they were able to heal one dog with Hemangiosarcoma. I don't see a whole list of dogs healed that way, but they do have that famous dog.
There are studies for certain supplements for increasing survival. Turkey Tail Mushrooms Maitake Mushrooms Pro4X, Bromelain would be a few. I used those and Modified Citrus Pectin, but I will tell you that the supplements got expensive and now I am doing diet and Nutritional Yeast. He is still doing okay heading into the fifth month after being diagnosed with Hemangiosarcoma. The vet said that he has never seen anything like it. I guess I trust WFPB more than Keto, but if he wouldn't eat the Vegan food, I would have tried the high oil next. It is the opposite philosophy, but they also are bringing the animal products down to 5% which is where T. Colin Campbell said that Cancer goes dormant.
I am going to say straight out that I haven't "healed" my dog. The owner of Bacon the Vegan dog had the tumor go away and my dog had a melon-sized tumor and it isn't gone yet. KetoPet using Keto got rid of 6 golf ball sized tumors in 120 days. Again, my dog had one tumor in his spleen which was the size of a melon and had other tumors. He wasn't supposed to live more than a week or two and he is still alive.
Someone on the McDougall site said that their dog had died of Cancer and they were WFPB and had him eating Keto and they wondered if he would have lasted longer WFPB. That made my mind up for me. Fail or succeed, I was going to do it WFPB.