I don’t know if there are any studies about medicinal mushrooms or if it’s just that they are part of TCM, traditional Chinese medicine. I haven’t looked for any but maybe there is something on AHVMA. I think they recently put on continuing education or are soon. You can probably find the speakers on their fb page.
I had a discussion about 6 years ago or so with my exotic/holistic vet about a friend’s dog with bone cancer. He used mushrooms on several occasions for dogs with bone cancer. He did say in his experience with bone cancer that you could heal it in one leg but it would come back in a different limb. I had another friend with a dog & her vet said to amputate & chemo. She decided to use colostrum & Noni juice. Her vet was surprised the dog lasted another 9/10 months.
I think it’s just something you’re going to try or you’re not. I had a dog 20+ years ago with horrendous allergies. The only thing the vet wanted to do was steroids & allergy shots. 10 mg of pred was the lowest dose to keep the dog comfortable & I went looking for a better option. Luckily I found one & she made it just shy of 16 years before I had to let her go.