Today we’re going to look at where the myriad color combinations in the Mastador breed (English Mastiff x Labrador hybrid) originate. It all has to do with coat color genetics between the two breeds. I will try to make this as non-technical as possible.
First, a simple introduction to coat color genetics is in order. You need to get this before the rest makes any sense. Both Mastiffs and Labs have recessive coat color genes. Recessive genes (like blue eyes in people) require that the gene be present in both parents, in order to show up in their puppies.
The Labrador Retriever has a very simple coat color genetic. There are three colors only: black, yellow and chocolate (all other colors are variations of one of those three). Black is the dominant color, while yellow and chocolate are recessive. That means, in order for chocolate or yellow to show up in puppies, the color must be present in both parents. As a result, 1st Generation Mastadors (where the parents and Mastiff and Lab, not two Mastadors) are usually the dominant Lab color, black, as the other two colors are cancelled out, by not being present in both parents. It is the strongest color gene between both breeds. That is why you get all black puppies from a yellow Lab and any kind of English Mastiff. About 90% of the time, 1st Generation puppies are black, some with white markings on the feet or chest.
Ancestral markings are color anomalies that you do not normally see in a purebred dog. Ancestral markings in Labs are usually represented as white “blaze” on the chest, or white toes or sox. When the Labrador Retriever was developed as a cross-breed, one of the foundation breeds was the St. John’s Water Dog. This was a black dog with white chest blaze and white socks. While the white has been bred out of the Lab, the genetics of the white spots are still in the DNA, so they come out from time to time. In English Mastiffs, white blaze or toe tips is a common phenomenon, so the gene from the Mastiff hooks up with the ancestral gene of the Lab, and produces blaze and white sox.
As an interesting side-note. The St. John’s Water Dog was also used as a foundation breed for another new breed, The Newfoundland Dog. The Newfie was actually the cross between the St. John’s and the English Mastiff! So, the genetics between these two breeds has proven to be very compatible over the last 150 years.
The English Mastiff has very complex coat color genetics that still have genetic experts trying to lay it out in a way that can be understood, but they are an ancient breed, with so much involved in their development over more than a thousand years. As recently as World War II, the English Mastiff was down to only six breeding females. In order to save the breed, one of the owners of the females bred them to the Great Dane, and the other bred them to the Bullmastiff. The English Mastiff never lost its “purebred” status, despite being cross-bred.
There are basically three English Mastiff colors in modern times, fawn (light, off-white color), apricot (red) and brindle (striped). In brindles, there are dogs with fawn (sometimes looks like silver) in the stripes, and others with apricot in the stripes. But there is so, so very much more possibility in Mastiff coat colors that are latent genes, just looking for an opportunity to express themselves. The expression becomes possible, apparently, with the pairing of the Lab genes.
Between 1883 and 1916 there were Mastiffs registered with the AKC as Blue Brindle, Black and Tan, Cream, Chocolate and White Spotted, according to one source I looked at. Eventually, standards were imposed by AKC and The Kennel Club (UK) and many of these color variations were bred away from. So, it makes sense that any color variation seen in the Mastiff world could still be expressed in a modern English Mastiff, as we see ancestral markings in Labs. That, in turn, most likely explains how a small percentage of 1st Generation Mastadors can come out in any number of variant colors and markings. There is some genetic piece in Lab DNA that occasionally finds a match with one of the ancient color gene possibilities of the Mastiff, and it comes out in the puppies.
Our own stud, Charlemagne of Covenant Farm is just such a color anomaly. He is tri-color, apricot, black, and tan, and comes from a fawn English Mastiff dad, and a black Labrador mom with chocolate markings on her legs.
Breeding into the next generations
In the second and third generations of Mastador breeding, the huge plethora of available color genes start showing up in every litter, often with various color combinations that outnumber the black puppies. The possible combinations are nearly endless, because of the color genes of the Mastiff, previously explained. How many of these colors will still be here a century from now is anybody’s guess, just as so many of the original Mastiff colors are no longer seen. On the other hand, ancestral colors and markings of the Mastiff that are now showing up in the Mastador, may well see a revival because of the genetic makeup of this new breed!