Hi Niki,
I am a very new member here so I most certainly do not want to appear to be plugging something that we have a commercial interest in, which we do, but it has also become an absolute passion for my family. Do yourself and your dog a favour and take a look at the research on Natural Astaxanthin, there's heaps of it on Google.
It's an amazing compound and the most powerful antioxidant on the planet being 500 times stronger than vitamin E. It's 100% natural and the scientific and anecdotal evidence is simply overwhelming as to the benefits of supplementing your dogs food with it. It's been a human supplement for over 10 years in the US and more recently Europe and has been touted the "best thing to hit the supplement market in 30 years". The sled doggers in Alaska have been using it as a secret weapon for many years but it is little known in dog circles elsewhere to my knowledge. It's been shown through clinical trials and scientific studies to improve cardiovascular health, helps prevent canine cancer, cataracts, immune system improvements and a whole lot more.
One of the largest pet food manufacturers in the world successfully applied for a US patent on Astaxanthin about 7 years ago but hasn't done anything with it. You really have to ask why.
If you can't find what you're looking for please PM me as we have years of research information on it. I don't think it is ethical to post website addresses etc up here so please let me know if you need pointing in the right direction.
Cheers
MAC