Harlequin Coat Colour Genetics
Neil O'Sullivan, Ph.D.
First off, regardless of what combos you try, large numbers of mismarked puppies are expected in all breeding involving harlequin (& merle) dogs. The best you can ever hope for is about 75% correct colour & pattern; 50% is the average if you count both Harlequin & Mantle offspring. You can reduce the expected number of correctly marked pups by at least 1/4 if you want to talk about harlequins specifically.
Merles are routinely born to harlequins, as are various other mismarks, including white merles (MM) also known as (deaf) white (merle) Danes. Therefore the problems of euthanasia of defective pups and the careful placement of dogs who fail to meet the standard is a routine part of the responsibility of any ethical harlequin breeder.
You can avoid all of this by breeding Danes of any other family but Harlequin. Harlequins have problems & challenges the other colours of Danes do not face. Mismarks in every litter is just one of them.
HARLEQUIN to HARLEQUIN:
You can expect, in a litter of 7, to see 2 (likely mismarked) black or Mantle pups, 1-2 merle pups, 2-3 harlequin pups & one deaf white pup (two are statistically conceived, but one of two whites conceived generally dies prior to birth).
Naturally people have 7 males in some litters, so some people will have 7 harlequins..or even 7 deaf whites, but on average, about 1/4 of the four basic colours is what is expected. Of course harlequins that carry blue or fawn or brindle can produce these "porcelain" dogs, sometimes called bluekin, fawnikin & brindlikin respectively. Flashy harlequins (with lots of white) could also produce piebalds: white dogs with "mantle heads & harlequin looking bodies" as they have been described. Harequinl-, merle- or boston-heads; dogs with white bodies & "caps" of colour (i.e. colour-headed dogs) also can result from the use of piebalds & flashy harls & mantles. These colour-headed dogs, also called piebalds, are essentially mismarked Mantles. Any time two dogs with the merle gene (incl. harlequins) are bred to each other, white merle (i.e. defective, dominant white) offspring are to be expected. The dominant whites that do survive to birth are normally defective & commonly deaf. Ethical breeders have traditionally euthanized most all whites at birth for these reasons.
HARLEQUIN to MANTLE:
This is the preferred breeding, all things considered, as it does not produce the Dominant (deaf ) White Dane. Expect the litter to be about 1/2 mantle, 1/4 merle & 1/4 harlequins. So in a litter of 8, expect 2-3 harlequins, 1-2 merles & 4 mantles. If these black pigmented dogs carry for other pigments, you may get fawns with blazes, or blue instead of a black basecoat Piebald & colour-headed dogs can occur, especially when flashy dogs are used.
MANTE TO MANTLE:
Produces only Mantle: that is, it cannot produce harlequins, merle or white Danes. Now piebald Danes that are mistaken for whites and for harlequins can be born to Mantle parents. This is more likely to happen when breeding flashy Mantles with big collars & broken blankets than with dogs who have more pigment. Mismarked blacks can also be born to this breeding as can piebald’s, so this breeding doesn't promise all show marks, it just guarantees having nothing but black and white dogs. It is possible (if unlikely!) that very flashy Mantles bred to each other could produce a puppy so white s/he could be deaf.
MANTLE TO (harlequins-bred) BLACK:
Would likely produce mismarked blacks. Mantles & (solid) Blacks also are possible.
BLACK to BLACK:
Would likely produce mismarked blacks when harlequins-bred blacks are used. Mantles & Blacks possible.
BLACK TO HARLEQUIN:
Produces as does Mantle to Harlequin, except, since a Black lacks the white collar of the Mantle, expect more mismarks under the AKC standard to occur, both in Harlequin & especially in potential Mantle offspring. Blacks will likely not be solid Black, but mismarked black, sometimes even called "harlequin black" it is so common to black to harlequin breeding. These "harlequin blacks" are disqualifying under the American standard.
Breeding or Buying Harlequins
It is never possible to control for a predictably fully white neck, even when two such animals are bred consistently together; the genes do not admit of such control. So it is not a trait worth giving an enormous amount of attention to, and the standard for the Mantle doesn't require a fully white neck anyway.
The standards say nothing about white "fronts" & chests and forelegs being even desirable, let alone preferred on harlequins or mantles. Note also the illustrated standard says markings ashionable or even more aesthetically pleasing. But it happens all the time, in and out of the show ring.
Since Harlequin and Mantle dogs of less than ideal pattern are inevitably necessary to a breeding program, it is best to stay within the acceptable range of pattern as documented by the illustrated standard. All sorts of romantic legends about the value of mismarks in breeding programs abound, but it's a simple fact that no truly dedicated breeder would ever prefer a mismark to an animal correct to the standard.
Apart from there being absolutely no documentation that mismarks "help" produce harlequins (in fact the evidence is quite the contrary), it is also obvious far too many mismarks are included in breeding programs simply as a cheap way to make harlequins. And it's practically an identifying trait of a poorly educated Harlequin breeder to give undo focus to colour and to talk of "colour pure" dogs and pedigrees.
Mismarks make more mismarks. Even if the Harlequin variant, as "obligate double heterozygote" cannot breed "true," they & their Mantle mates can and will produce more correctly marked animals than mismarks do. And the problem with breeding & getting Harlequins anyway is not license to sell and breed every imaginable mismark that comes out of a harlequin litter.
Many of these myths about the value of breeding mismarks are so obviously self-serving. Many who breed them are simply uneducated about harlequin genetics it would seem. With the possible exception of the mantled merle, the mismark who is of actual breed value is a rare creature from an unusual breeding, so there is no justification for routinely including mismarked animals in a breeding program.
Deaf/defective dogs used in breeding programs are said by some to have an increased incidence of deaf/defective offspring, even several generations later, and many predominately white dogs are not of a useful genotype anyway, but can contribute to problems in the puppies.
For us to safely breed dogs carry "lethal" & "semi-lethal" genes we need to consider the implications of simultaneously carrying 2-3 white genes well documented to cause serious health defects when "used to excess" to produce predominately white dogs. We should not encourage an increase in defects purely for the sake of a (currently) preferred aesthetic, sale of breeding stock, or ease of breeding choices.
THE "WHY" OR RATHER THE "WHY NOT" OF BREEDING MERLES:
NOTE that these comments do not necessarily represent my personal views, but provide the new breeder & those curious about this subject a basic reference to the basic aspects of why merles are not recognized under any Great Dane standard anywhere or anytime as acceptable breeding animals.
1) Merles are a disqualification under all standards for the Great Dane--and have always been. That is enough, in many registries, for a dog to be denied "papers," so this is obviously always been thought a very poor breeding choice.
2) Historically it was thought that if you restricted the gene pool to Harlequins and Blacks(including Mantle), you could rid the breed of the merle gene by denying merles breeding and show status. Breed traditions are often 100s of years old, as is the case with merles being considered a non-standard color. When this breed was codified as a pedigreed breed in the mid 19th century, certain colors were chosen to represent the breed's typical look. Amongst these was the Harlequin Great Dane.
This was just the beginning of the era of understanding genetics and at the time it was thought (by all breeding plants and animals) you could simply select for certain traits & against others by choosing one breeding over another. Merles for centuries have been known to produced defective pups, which was a practical disadvantage for the breeder. This happens in any breed or cross bred dog that carries merle (and it's a gene you cannot always "see" which is another aspect of this topic). Harlequins were widely thought until very recently to be a completely different dog than a merle. Their traditional breeding partner was black (not necessarily solid black), a breeding that produces harlequinsl, merle & black(mantle). Discarding the merles as breeding stock was thought to end ultimately in NO merles being born and so raising the standard of puppies in general & creating more "purity" of colour. And at this time in the breed's home country blacks were NOT shown, they were simply considered a by-product of Harlequin breeding and used then as you suggest merles be used now--to produce more Harlequins.
This approach in breeding has been used for 1000s of years in all domestic stock and works 99% of the time. Harlequin genetics just happen to not fit the normal mode & it was only when both the merle & harlequins genes were discovered that it could be finally established that Harlequins always have a merle gene & are actually a merle variant. This is very new information and still has not been fully published. When this data is published and reviewed by such organizations as the GDCA and DDC it may well result in alterations to these traditions. But historically, a variety variations on the merle were used & the results outside of using the Harlequin itself were generally not good which contributed to their being disqualified. In other breeds which allow the merle (very few BTW), merles are not supposed to be bred to each other, to avoid the production of white merles: those defective, predominately white pups. Merles LACK the necessary genetics on their own to produce harlequins: no one has ever documented a merle to merle breeding that produced harlequins. So by all reliable reports, merles as a group do not productively contribute to the harlequin-mantle gene pool. That said there are ways to properly use such as the Irish-marked merle dog (i.e. mantled merle) effectively & even the "double" merles (whites & merlikin), but the former has only one effective breeding (breed to a Mantle testing positive for the harlequin gene), and the latter puts the breeder in the murky ethical waters of producing and then using in a breeding program dogs expected to have sensory deficits.
2) It is certainly and always the case that anyone who has not established a *sterling* reputation & can explain to the general dane fancy's satisfaction the reason to break such a general rule of breeding better be prepared to be considered unethical by most if not all others concerned about ethical breeding. This is a case where making an exception to the rule is better NOT done but for the rarest of cases where the person in question has a long track record of good practices, the production of Champions under ethical constraints, AND who has an exceptional & rare enough situation on their hands to warrant a probably once in a lifetime event. People who sell & breed merles (including merlikins) as breeding stock on a regular basis can simply be generally assumed to be commercial (i.e. for-profit) breeders whose goal is cash cropping harl pups, not breed protection. These dogs are also bred in ignorance by people only casually involved with the breed. Needless to say, however well meaning, these breedings do not contribute to breed betterment either.
3) A Boston merle, the most likely choice as a breeding partner to a harlequin, is essentially a "true" Boston (i.e. Mantle), with the added problem of producing deaf white & other defective puppies, which does not occur in a Mantle to Harlequin breeding. So a Mantle is always preferable, on this account, to a merle.
4) "Merlikins," a white base-coated dog with black & grey markings & a dog that lacks the harlequin gene, have been bred on occasion to Mantles to produce harlequins. But this is a risky breeding for several reasons. Merlikins may be genetic whites (MM), so then are often deaf &/or have eye defects (& without a BAEF/CERF no one can say a dog's eyes or ears "are fine"!), most (Mm) merlikins will NOT produce properly marked harlequins under any circumstances, & the harlequins they DO produce are simply the result of their Mantle (Boston) mate carrying unseen the factors needed to produce harlequins. And they are disqualified under the standard. All this means merlikins are established as a poor breeding choice as a rule. So, again, a properly marked animal, in this case a show-marked Harlequin, would be preferable to the merlikin.
5) The long & the short of breeding merles (& other mismarks, for that matter) is, if you have to ask about the whys & wherefores, you probably "can't afford it;" can't afford the potential for disappointment, even disaster & dishonour likely awaiting you. Unless you are dealing with a publically esteemed breed expert really caught in a corner, you can pretty much assume someone using mismarks (e.g. merles, Piebald’s, and other mismarks) routinely in their breeding program is less than knowledgeable & less than ethical. This *is* a case of guilty until proven innocent.
(6) Bear in mind this is an internal Dane dialogue & one predicated on tradition. There are several breeds where merles are perfectly acceptable to breed (even if they are not bred typically merle to merle, as all try to avoid the production of "double" merles (white merles), technically known as homozygote merles. And despite Dane tradition, logic and new research suggests that Irish-bearing merles ( mantled merles) could arguably have a legitimate place in even responsible breeding circles to help secure the gene pool. By this I mean if a reputable breeder had a show marked merle equivalent to a Mantle and Harlequin (both of whom, to meet the standard, must exhibit the "Irish" pattern essential), this might prove useful to the breed. First it would mean the Harlequin breeder, notoriously restricted as to breeding choices acceptable under the standard, would have a few more puppies to choose from, so could more often choose quality over colour. Secondly if mantled merles were accepted under the standard, this would put them on an equal footing with Mantles & Harlequins, which would help demystify this colour & that would likely result in a reduction in buyers purchasing pet puppies from poor breeders. Which isn't to say all agree with this argument or that then it's "okay" for all sorts of merles to be randomly bred as cheap alternatives to Harlequins, but that at some time in the future when we know more about the genes involved, we may have to revisit this issue, even consider the Mantled Merle as a useful show/breed dog.
Of the 16 possible combination four (25%) are HH lethal, leaving one with 33.3% Harlequin, 25% Black-Mantle, 16.6% merle & 25% white expected. Note that these MM whites are semi-lethal so that one usually sees less than the expected ratio actually born live. So this gives potentially 7/12 show-marks (58.3%).
Of the 8 possible combinations two (35%) are semi-lethal whites, with 25% each expected of Harlequin, merle, white, and Black-Mantle. Note this is a lower rate of show-marks (maximum 50% possible) than what is expected from a harlequin to harlequin breeding as merles do NOT carry the harlequin-factor so cannot contribute to the production of Harlequin offspring.
There are two different kinds of Black-Mantle dogs--those who are harlequin-factored and those who are not (& you cannot be sure if a Black-Mantle is harlequin-factored until you breed him). If a harlequin-factored Black-Mantle is used, expect 50% Black-Mantle, 33.3% Harlequin and 16.6% merle (or two harlequins for each merle produced). If a non harlequin-factored Black-Mantle is used, then the ratio of harlequins-to-merles is one-to-one. Black-Mantles remain 50% of the litter with 25% each Harlequin/merle expected. So in this case you can expect from 75% or more of the litter to be potentially show-marked.
Again there are two possible kinds of whites: harlequin-factored whites and non-harlequin-factored whites. If the white used is harlequin-factored then expect 50% white with 2 Harlequins for every merle. If the white used is not harlequin-factored expect 50% white with the other half of the litter split evenly between harlequins and merles. And recall that some whites will die and others will have eye-ear, etc. defects as this is a semi-lethal gene combination. About 3/4 of this litter is disqualifying in colour with about 1/2 of them carrying a semi-lethal gene combination.
Since white can have one of two genotypes and Black-Mantle can also have two different genotypes, there are four possible breeding combinations here. When both partners are harlequin-factored there are two Harlequins produced for every merle. When only one parent is harlequin-factored, there is a 50/50 split between Harlequin and merle puppies. When neither parent is harl-factored, the litter is all merles. "White to black only works if one or both parents are carrying for the harlequin allele."
50% of this litter is expected to be white. If the white is harl-factored there is one harlequin for every merle, if not then only merles are otherwise produced. Merle cannot aid in the production of correct color.
Again the production of Harlequins rather than merles depends on whether the Black-Mantle is harlequin-factored or not, as merle cannot aid in the production of Harlequins. If the Black-Mantle is harlequin-factored expect one Harlequin for each merle and each Black-Mantle. If the Black-Mantle is not harlequin-factored, expect a 50/50 split of Black-Mantle and merle puppies.
The Harlequin is a dual heterozygote by definition, carrying one gene for harlequin-factoring and one merle gene. It should be clear from the diagrams presented why the Harlequin will never breed true. Other important points noted are that (a) merles lack the harlequin-factor by definition and cannot contribute to the production of Harlequin puppies, that (b) Blacks (incl. Mantles) and whites (white merles) can be harlequin-factored or not and only if they are harlequin-factored can they contribute to an increase in the percentage of Harlequin puppies expected.
A few more notes from Dr. Neil O'Sullivan: "You will note that the use of deaf whites is highly correlated with more deaf whites in the progeny or grandprogeny. Also the use of deaf whites and deaf merlequins correlates with a higher incidence of deafness and eye defects even in the harlequins."
"In short...I think breeding from deaf dogs is not smart as it increases the frequency of genes which do not encourage pigmentation of the head and thus middle ear and retina and in so doing not only set us up for more deaf whites but deaf merlequins and deaf harlequins too. Yes, deaf harlequins, as you know from rescue are not as rare as we breeders would like." (The general anecdotal estimate is that 90% of whites are deaf and 50% have defined eye defects. Assumedly the estimate for merliquins is not dissimilar.)
"A harlequin is HhMm in genotype with the gray of the merle genotype converted to white by the Hh genotype. Thus the Harlequin is predominantly a white dog with black torn patches, a merle is (hh Mm) a gray dog with black torn patches and a merlequin is a modified merle ( hh Mm tw tw). A harlequin with tw tw ["merliquin"]genotype is usually a "mixed" color [e.g. swirly-merle, harlie-merle or popcorn harl] with almost as much merle as black patches. Tw the non tweed allele is dominant." And a TwTw Harlequin is the dog who will not produce these recessive "tweed" mismarks. Tweed produces a merling pattern with more variation in shades of patches and generally larger patches (or more larger patches).