I have asked the manufacter the question as posed and this is the response. Can you all note that the salmon they use is NOT SMOKED.
The salmon oil we use is the highest quality food-grade Scottish salmon oil available. I do know its farmed salmon, purely because it’s impossible to have a consistent high quality supply of wild salmon oil and I would have ethical concerns about depleting the wild population of salmon for a commercial product.
People understandably want to know what the salmon are fed on, although like any other branch of the food industry it is heavily regulated as to what is permitted or not. Astaxanthin and canthaxanthin are included in salmon food to make the flesh pinker, but despite the scary-sounding long ‘scientific’ name these are not ‘dyes’, but pigments widely found in nature (i.e. the same type of thing which makes carrots orange) and which are actually considered nutrients rather than anything ‘dodgy’. For instance canthaxanthin has some very nice anti-oxidant properties, in the same vein as Vit.E. Just because they’re made artificially doesn’t make it harmful; anymore than vitamin C made by a chemical company is harmful compared to the ‘natural’ version.
Despite my best efforts, I can’t find any research or papers which suggest that there is any suggestion that these pigments can harm dogs or humans, although there is some evidence that when salmon is smoked (which our isn’t) the combination of astaxanthin and smoke can results in products which some dogs are sensitive to.
From the thousands of tonnes of Nature’s Harvest we’ve sold since it was launched 18 months ago I can honestly say I haven’t had anyone tell me that their dog has reacted to ‘something’ in the food.
I do hope this is of some help. Please get back to me if you have any further concerns and I will do my best to answer them.