Reality in photography is not what the camera records, but what the human minds remembers.
Generations of photographers have used camera movements to "correct perspective" under the wrong assumption that building walls don't converge (they do converge, visually, although the effect is amplified if a wide-angle is used which can make the convergence unnatural. I find total correction of perspective very unnatural).
By the same token, generations of photographers have used "warming" filters on subjects lit by a blue sky, and which were evidently lit by a blue sky, to remove the blue cast which was truly there and which could be expected to be there.
Sheep can have a "dirty white" appearance, at least here in Italy the sheep we have (which are different breed from the one depicted) tend to be more "neutral", while other sheep, mainly British, are indeed yellowish (was always puzzled by this difference in colour). It's not important how the sheep looks. It's important how do you want to portray it.
The rule for photojournalism is that you cannot remove not even some litter on the ground. For "editorial" retouching has always been part of the trade.
A portrait - generally speaking - cannot do without retouching. In the old times (and possibly in present times) a specific figure, called a spuntinatore in Italian - I don't know the English term - would patiently retouch a portrait for hours or days in order to please the buyer. The portrait might then have been published, who knows, on a magazine.
I don't think, under this respect and to make an example, that Yousuf Karsh portraits are exempt from retouching, which doesn't take away the authenticity, in my opinion. And why a portrait on a magazine cover should be treated differently, be it a model or a dog?
If "truthfulness" and lack of manipulation was the imperative ethic, then make-up itself should be possibly more questionable than retouching.
The right colour of the sheep is the colour the sheep was rendered with, unless that is a scientific publication about that kind of sheep.
Photography IMO IS manipulation. When the manipulation is not credible or ridiculous, then we just have bad photography, but not something ethically illegitimate, photojournalism case excepted.
I don't understand how can people buy nocturne pictures of Rome with a full moon not just 10 times bigger than natural, but even in the North sky! Somebody likes rubbish, that's all. Falsifying the wrinkle on a cheek is really nothing in comparison.