Disclaimer: I am not any kind of doctor, nor am I a formally trained herbalist. I'm just an ordinary dog owner. I read all I can about how to take care of my dogs, and I have used herbs on them from time to time.
In my opinion, it can be okay to use Metacam with certain holistic remedies. You don't want to use it with something that is too similar to it, like willow bark, because that might be like giving an overdose of the same thing. I see no problem with giving either acidopholus, Rescue Remedy, or both, along with Metacam.
Personally, I would never choose to use colloidal silver on either myself or my dogs, because I have read accounts from people who had their skin turned permanently gray by using it. From what I understand, once you start taking colloidal silver, it never gets excreted from your body. It builds up and up in your system, and it needs someplace to go, and it gets deposited into your skin and stays there. I don't like the idea of taking something that my body can't get rid of.
The dandelion, milk thistle, eyebright, and olive leaf, I don't have too much experience with. I would want to know for a fact that any herb I was thinking about giving to my dog had been proven nontoxic for dogs. Dogs can't take everything that humans can. Some substances might be harmful to dogs without being harmful to humans. Or the dosing might be completely different and not just a simple matter of adjusting for the lesser body weight of a dog.
There are a few veterinarians that use herbs. It would be good if you could get a consultation with one of them. I don't really know where to direct you. You would probably just need to do an internet search.
Good luck. It is nice that you care so much about your dogs.
I know a bit about herbs, but have only fairly limited knowledge when it comes to herbs for dogs.
The problem with herbs is some do not mix at all with prescription drugs, and that's the same for dogs as it is with people. But with dogs there's the added problem that not all herbs which are fine for us are safe for them.
However, Milk Thistle and Dandelion are fine for dogs. I know that, and as far as I can make out will not clash with Metacam. In fact, Milk Thistle (in the correct dosage) will help to protect the liver somewhat against any toxic effects of the drug Metacam. I can't comment on Eyebright, as I really don't know about whether it's OK or not. Neither do I know anything about Colloidal Silver.
The chief constituents of Dandelion root are Taraxacin, acrystalline, bitter substance, of which the yield varies in roots collected at different seasons, and Taraxacerin, an acrid resin, with Inulin (a sort of sugar which replaces starch in many of the Dandelion family, Compositae), gluten, gum and potash.
There are some chemical properties of Eyebright that have still not been researched, so they are a bit of a mystery.
Acidophilus should be OK, as that is basically the "good" gut bacteria, which I cannot see interfering with Metacam.
Rescue Remedy is pretty strange stuff. It has homeopathic quantities of herbs (that is, diluted to such a degree they are hardly even present!) I believe it works more on the "subtle body" than the physical body (Yes, I know that sounds a little "nuage-airy-fairy"....but I can't think of a better way to describe it. The weird thing is these homeopathic remedies can have brilliant effects! So I very much doubt if that would clash in any way with Metacam, at least not chemically.
I have no knowledge of Olive Leaf, whether it is, or not, safe for dogs, and whether it would clash.
Basically it's always best to consult a professional if combining ANY herbal treatment with either over-the-counter drugs, or prescription drugs, of any kind. A fully qualified veterinary Herbalist would be best.
No, ONLY if Colloidal silver is used in EXCESS will it turn skin grey - and it IS reversible.
Coloidal silver when used correctly IS an excellent remedy -- I've used it on my cats, and for myself-- even a VET I met says she has used it on occasion on some of her patients.