I'm sorry that you have to be here, but glad you found us.  Be sure to register because this site ROCKS as far as information and support!!!  My 8 year old Golden Retriever also had osteosarcoma and had a front amputation in late July.  We started him on the K9 Immunity and Transfer factor shortly after that.  Now, I don't have a long term testimony but I can tell you this:

1.  When I went to a natural foods store to see if they had anything they recommended for him, they suggested a transfer factor and immunity supplement.

2.  A close friend of mine owns a pharmacy and recently his dog was diagnosed with (really advanced) lung cancer.  Knowing that we've been dealing with this for a while, he called me to see if there was anything else that he should be doing that he hasn't started yet.  When I mentioned K9 Immunity , he knew about it and had already ordered it.  He said it was definitely a good thing and since he's a pharmacist, I figured he knew what he was doing and if there was a way to get it better/cheaper, he'd be able to do it.

3.  It generally doesn't hurt anything, and it may seem silly, but I like the fact that at least I'm doing something...

4.  It's easy to give.  McGwire generally is somewhat picky about pills (though nothing like some of the dogs on here!) and I just throw the pills into his food and he gobbles them right up.  The transfer factor 'tablets' are big but they must be tasty!

5.  I swear McGwire feels somewhat better because of it.  He seems to be feeling better, and 6 weeks after the first chest x-rays, he's had no lung metastisis (we aren't doing chemo because of his immune system issues.)

It's expensive, but I feel like it's worth it.