Do they recommend splitting up color breedings because of the chance of getting an 'undesirable' color like chocolate? Why exactly do they not like the off colors? You'd think by only choosing to breed certain colors they are reducing the genetic pool already smaller than what it was. That's never healthy..
They also cull ridgeback pups who are born with no ridge. It's terrible.
I knew about the lethal part of the double merle gene and the increased chance of deafness but not all the other inherited problems of that and mostly white dogs..
I do not disagree with showing but I disagree with some of the practices that go along with it.. over breeding stud males, and disallowing colors that are prevalent in the gene pool.
white danes often suffer from sensory defects, which are generally simplified to "blindness and deafness". getting more technical, vision impairment can be caused by a range of eye anomalies and defects associated with the merle gene. in the list you quoted, congenital cataracts through colomboma are all conditions relating to the eyes. deafness is caused by a lack of pigmentation in the inner ear, so the interaction of merle, harlequin, and piebald genes lead to deafness.
lack of pigment in the skin also puts white dogs at a higher risk for skin cancer and dermatitis. however, i am unsure about the claim that white danes suffer from follicular dysplasia, which i have always seen associated with the "blue" dilute gene.
photo-induced epilepsy has been associated with the eye defects mentioned above.
i have also heard that fertility is effected by the double merle gene but don't know enough about it to comment. as far as social instability goes, i tend to disagree that white Danes are any less temperamentally sound than a pigmented counterpart of similar breeding. i have interacted with several white danes, many with sensory defects and have not noticed any "social instability" in well-trained animals.
i also wanted to point out some flaws with the article so no misconceptions are spread here. many times white are born completely normal with no defects. this is not the norm and does not justify producing them, in my mind, but whites are also not always riddled with defect. some have normal eyes and vision but cannot hear, others are blind but have perfect hearing, occasionally there are whites with severely deformed eyes, skin, and neurological problems, and sometimes they are no different than a black Dane other than their susceptibility to sunburn. there is definitely a range.
also, merlequins (double merles without the harlequin gene) suffer much less frequently from sensory defects than whites because they retain more pigment. merlequins (and whites for that matter) are no more likely to suffer from autoimmune or neurological problems because of their color. those issues have more to do with whether the breeder is "reputable" and focusing on health and genetic diversity.
the article blurs the lines is this manner as well, so i will clear things up - inbreeding causes immune problems (and other genetic issues to be sure) but inbreeding does not have anything to do with the production of white or merlequin great danes. two totally unrelated harlequins bred to one another will still produce puppies with sensory defects. they are just less likely to produce dogs with weak immune systems.
the article alludes to the fact that the harlequin Dane Rumpus died an early death. this has nothing to do with the fact that he is a harlequin great dane, nor that he was produced from a harlequin to harlequin breeding. harlequins do not suffer from any color-related ailments. normally pigmented dogs from harlXharl breeding do not suffer from any aillmets related to the color of their parents either.