Brindle Basics: Who Knew Stripes Could Be So Complicated?
Many Molosser breeds have brindling, a pattern of black striping not dissimilar to that of a tiger.
Notice we said pattern: Brindling is not a color, though many fanciers refer to it — mistakenly — as such.
And that’s not the only area in which brindling has created confusion and misinformation among some Molosser fanciers. Indeed, from the “ultra brindles” of the Boerboel to the “blue brindles” of the Cane Corso and Neapolitan Mastiff, brindling is often misunderstood, even among experienced breeders.
Let’s try to set the record straight once and for all.
Inherit the Stripes
While brindle is a ubiquitous pattern in dogs, and arguably an ancient one, there is no reliable genetic test for it, leaving open the possibility that our understanding of how this pattern works might change once researchers crack the genetic code. We’re not going to get into the alphabet soup that is genetic notation, but for science geeks, genetically, the shorthand for brindle is written as kbr. (Expect to be confused if you peruse your brindle dog's DNA results: Because of the lack of a commercial test, brindles are reported as "KB/ky," since elements from both the dominant black and yellow alleles are present. These dogs are not dominant black, which the KB allele typically denotes; instead, they are fawn/red.)
Brindle is a dominant trait — in other words, it can be transmitted by just one parent, so any true brindle dog by definition must have a brindle parent.
A seeming contradiction to this is found among black Cane Corsos and Neapolitan Mastiffs, which sometimes do produce brindle offspring. That is because a dominant black dog can indeed be brindle: It’s just that the black coat is dominant over the brindling. An unscientific way to think about this: The black brindle stripes are covered up by the black coat. Such dogs are genetically brindled, however, and they can produce brindle offspring.
Brindle has been a long-standing pattern in Bullmastiffs (above) and Mastiffs (below). It is not as common as fawn in those breeds, for a variety of reasons.
A similarly oddball scenario exists with so-called “straw” or “paglia” Cane Corsos. These incorrectly colored dogs carry two copies of the “e” allele, which masks any expression of black in the coat. (This recessive red does not change the color of the pigment, including nose color, though it can cause fading to a pinkish gray tone.) Even if they are genetically brindle, such dogs will not appear to be, because the expression of the black brindling in their coat is suppressed by this “knockout” gene. But since they, too, are genetically brindle, they can produce stripey sons and daughters.
Straw Corso in Italy in 2000. Not coincidentally, there was a Maremma on the property. Such dogs can never have brindling — or a black mask, for that matter — because they genetically cannot express black in their coat.
Brindling is associated with base coats that are fawn, yellow and red. This is why you will never see a zebra-striped dog: Brindling does not occur with white as a base color, and can never occur on top of white spotting.
As for the brindle striping itself, it is always black — period, end of story. Or at least, it starts out that way. But other genes can act on the black brindling, turning it into different shades and colors.
These Presa Canarios demonstrate basic brindle: Black stripes on a fawn or red background. Dilution can change the color of the black stripes to a brownish red or blue.
The most common example of this in Molossers is when color dilution is present. The allele for color dilution is recessive, which means two copies are required in order for the phenotype, or appearance, of the dog to be affected.
Red brindling — that is, black brindling that is turned liver/chocolate brown — is caused by two copies of a black-modifier allele, or “bb.” This gene also turns the nose red, which is acceptable in only two Molosser breeds: The Dogue de Bordeaux, which should not be brindled, and the Neapolitan Mastiff, which can be.
So-called mahogany Neos have red noses. When these dogs are brindled, these modifying b alleles turn the black stripes various shades of chocolatey red.
A reverse brindle mahogany Neapolitan Mastiff puppy. The lighter tan stripes here are the base coat of the dog, not the brindling. Instead, the predominant brown color is the black brindling that has been diluted. We discuss reverse brindling in greater depth further on in this story. Photo: Wild Child Neapolitan Mastiffs.
Blue brindling, which is caused by two copies of the recessive d allele, occurs in a number of Molossers, including the Neapolitan Mastiff and Cane Corso. Just as this “blue” gene turns the base coat of a black dog to gray (or “blue”), it does the same to the black brindle striping.
Blue is the most common brindle dilution found in Molossers. To understand this common pattern, first consider the brindle fawn Cane Corso below: a buff-colored dog with black stripes. She is not a dilute.
A brindle fawn Cane Corso. The stripes are solid black and undiluted.
If she were to become a dilute — a color called formentino in the breed — the tips of her fawn coat would develop a silvery cast (not unlike the dull hue of a brown paper bag) and her brindling would become gray, like the blue-brindle puppy below. By definition, both colors are noticeably duller, and so is the contrast between them: While the difference between the undiluted dog’s fawn base coat and the black of the brindle stripes is quite dramatic (above), their corresponding dilutions is more subtle (below).
Blue brindle Corso puppy. Photo: En Una Palabra kennel.
The brindling on this blue-brindle puppy does not express as black because the two copies of the color dilution (written genetically as “dd”) are altering its appearance. But genetically speaking, that brindling is still black. And if the puppy did not carry two copies of the recessive dilution, its stripes would indeed be black.
“Reverse brindle” is a term one comes across frequently in Molossers and related breeds, including the Boxer. It is used in two different — and, in fact, opposite — ways, depending on the breed. And both definitions are technically wrong.
In Boxers, the term “reverse brindle” refers to dogs whose brindling is so heavy that it looks like the colors of the base coat and the brindling have been switched. So in Boxers, a "reverse brindle" is a fawn/red dog whose black striping is so heavy it gives the appearance of a black dog with red stripes, which is definitely not the case genetically.
A comparison of two Boxers. Both are red-fawn with black brindling. The dog at left is referred to as a "reverse brindle" because the black striping is so heavy, is makes it appear as if the red-fawn base coat is the brindling, which it is not.
In Boerboels, this phenomenon is known as "ultra brindle."
This Boerboel would be considered an "ultra brindle": His black brindling has exceeded his fawn base coat. Photo: Fernando Moreno.
The Neapolitan Mastiff's AKC standard actually mentions "reverse brindle" in its section on color, stipulating that "When present, brindling must be tan (reverse brindle)." Genetically speaking, however, the so-called "tan brindling" is the fawn/red base coat that is covered by heavy brindling.
And now for the flip side: In Cane Corsos and French Bulldogs, breeds in which heavy brindling is extremely common, "reverse brindle" is used incorrectly to mean the opposite of the above: In those breeds, "reverse brindle" refers to dogs whose brindle stripes are not so overwhelming as to obscure their fawn or red coats, like the female below. This comes from the mistaken idea in the breed that it is the black brindling that is the base coat, and the visible slivers of red/fawn base coat that is the brindling.
These dogs are simply brindle. Period.
This case of mistaken identity extends to the term "chestnut brindle," which is used among Corso folk: "Chestnut" refers to the red base coat visible through the heavy brindling.
So, once again, for those in the back: Brindle is black. Reverse brindles are dogs with heavy black brindling over a lighter-colored base coat. It is just that the volume of brindling is so great it covers over the base coat and makes it appear that the dog’s base coat is black when it is not.
Three French Bulldogs that are shades of the same color — fawn. The dog at right appears black, but on closer examination you can see the fawn base coat peering through the heavy brindling. Under all that brindling, he is fawn, too.
Too Much of a Good Thing?
In some breeds, this type of heavy brindling is not preferred: The Great Dane standard, for example, makes a point of asking for a “chevron pattern” distinguished by “black cross stripes” — “the more distinct and evenly brindled,” the better. As a result, one doesn’t see heavy reverse brindles (that is, so heavy that they appear at first glance to be solid black) in the Dane ring.
The Great Dane standard emphasizes striping that is clearly defined and even. Photo: Darlene Bell-Bergan.
By contrast, most Molosser breeds that can be brindled — including Bullmastiffs, Mastiffs, Cane Corsos, Neapolitan Mastiffs and Boerboels — don’t have any limitations on the quality or quantity of their brindling.
One Molosser breed that has an inordinate number of reverse brindles is the Neapolitan Mastiff. Its AKC standard says: “Some brindling is allowed in all colors,” but when present, that “brindling must be tan (reverse brindle).”
In other words, all the black Neapolitan Mastiffs with traces of light-colored "brindling" that you see are really red or fawn dogs with reverse brindling. But since black is an acceptable color in the breed, the confusion between base coat and brindling doesn’t matter.
An excellent example of reverse brindling in a Neapolitan Mastiff. This female is not black — her brindling is! Under all those overlapping stripes, she is fawn. You can see traces of that lighter base color on her neck and upper thigh. Most fanciers would call her black, and from a show perspective, that's irrelevant, as black is an accepted color in the Neo. Photo: John Seibel and Stacey Johnson.
But in breeds with a disqualification for black, reverse brindles can pose a serious problem.
As we discussed earlier, the brindling on French Bulldogs is often so overwhelming that only a hint of the fawn or red base coat is visible. Judges confronted with such dogs in the ring invariably ask the handler to “Show me the brindle, please.” Despite the wrong terminology — what the judge is asking to see is evidence of the base coat, not the brindling! — handlers will sometimes point out as few as two or three fawn or red hairs. This is enough to prove that the dog is indeed brindled and not black. (Don’t ask me what happens when those three hairs shed out — hopefully, they take turns!)
In a recent conversation, a French Bulldog breeder shared that their kennel's reverse brindles had become so black that it was becoming impossible to find even a few non-black hairs in the coat. Even though technically they are not genetically black, such dogs appear to be, and judges— who to date cannot perform DNA panels in the ring — must disqualify them.
At first glance, this French Bulldog puppy appears black. But the subtle red shading indicates that it is instead heavily brindled, with only glimmers of its red/fawn base coat peeking through.
The same dilemma exists in Boerboels, many of whose so-called “ultra brindles” appear at first glance to be solid black dogs. A close examination of the coat that reveals even a small band of fawn or red base coat on a hip or shoulder is enough to determine that the dog is a reverse brindle instead of solid black.
An ultra-brindle Boerboel who at first glance appears black. But there is brindling visible on her neck. Photo: Christina Ross, Revelation Boerboel.
While breeding for color is a luxury most Molosser breeders cannot afford — achieving correct head type and correct structure are far bigger considerations — avoiding the repeated breeding of reverse brindle to reverse brindle in breeds with a disqualification for black might be a prudent consideration.
My appreciation to Stefanie Henneboehl of www.coatsandcolors.com for her input and clarification of the genetic terms used in this article. Thanks also to Bill Goetz and Anne Latimer Goetz for providing Embark results and corresponding photos to confirm reverse brindling in the Neapolitan Mastiff.