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Greyt Expectations

An Australian kennel does a controversial breeding in the hopes of improving Mastiff health and longevity

At Modern Molosser, we don’t shy away from controversial stories. This interview fits that bill – and then some.

Jennifer Willshire and her husband Simon of Gammonwood Mastiffs in New South Wales, Australia, rocked the Mastiff world recently by unveiling their backcross breeding program: In a bid to improve health and soundness in their dogs, they have crossed one of their Mastiff bitches to a Greyhound, producing a litter of “Greydogges.”

To be sure, this is not the kind of one-off cross that produces Labradoodles and other “designer dogs”: The Mastiff/Greyhound crosses will be bred back to purebred Mastiffs, just as a Pointer was introduced into American Dalmatian lines in the 1970s to eliminate an endemic uric-acid deficiency in that breed, and then backcrossed to produce a line of dogs that were clear of the problem. Nonetheless, the Gammonwood project is controversial in Mastiff circles, to say the least, and has occasioned its fair share of debate among breeders and fanciers.

Previous to this litter of “Greydogges” – initially, they were also dubbed “Greiffs”  – the Hillshires’ claim to fame was their “Gammonwood Tale,” a beautifully produced video exploration of the Mastiff’s origins and history.

The Hillshires have kept two Greydogge puppies, Hedge and Torpedo, who will be used in the Gammonwood program. Another, Freddy, has been imported by Hillse Mastiffs in Holland, where he’ll be used in their breeding program if he passes all his health screenings. A bitch, Shield, is also going to Holland to take part in an outcross program in an Irish Wolfhound kennel, another giant breed where longevity and overall health are a concern among some breeders – again, if all her health checks are clear.

Here, Jennifer Hillshire discusses the Gammonwood backcross project and its goals, the reason they chose a Greyhound and not a closer Molosser relative, and the reaction of fellow breeders and the Mastiff faithful.


Is this a traditional backcross project, to try and infuse some health and soundness into the breed via the Greyhound, and then returning to a modern interpretation of Mastiff type? Or do you intend to move in the direction of a more “running hound” style Mastiff?

Our backcross project is a traditional one. We love our English Mastiffs and would like to get back to Mastiff type quickly. However, we are hoping for a little bit of a clean-up along the way. The Mastiff breed standard states that exaggeration of wrinkle or excess of loose skin is unacceptable, and it calls for absolute soundness along with a powerful build. As such, we need to address common structural faults and exaggerations that have either been fixed in the breed from decades of close breedings, or have just crept in as a consequence of selection for certain traits over others.  


The aptly named “Eve” (Gammonwood Even Burn) and her “Greydogge” puppies at five months old.

The aptly named “Eve” (Gammonwood Even Burn) and her “Greydogge” puppies at five months old.


On your website you mention there is a need for “a greater tolerance of natural breed variations.” Can you be more specific?

There desperately needs to be greater tolerance for natural variations in breeds because breeding for just one particular look can have devastating consequences to a breed’s gene pool. 

Great uniformity in dogs generally requires their genes to have high levels of homozygosity, and increases in homozygosity are proportional to decreases in health. We know it’s possible to have a whole group of dogs that are easily identifiable as Mastiffs without having them all look exactly the same. Some people mistakenly believe that excessive white or non-standard coat colors on a Mastiff can cause us not to be able to identify the breed, but there are no color restrictions in Greyhounds and people do still easily identify them. Mastiffs are often passed over for breeding simply because of a cosmetic trait that has no bearing on health, temperament or functionality. The offending traits are often caused by a single recessive allele or half a gene out of the roughly 25,000 that every dog carries. In the case of excessive white, which is deemed unacceptable in the UK breed standard, there generally isn’t even an allele or gene involved. It is simply residual white left over from the puppy not baking long enough in the uterus to get full color coverage.  

Every purebred Mastiff that gets discarded unnecessarily from the gene pool diminishes the gene pool. This ensures less of a future for all purebred Mastiffs. Numbers in a breed don’t count for much; it’s the effective population size of a breed that really matters. We may have 10,000 Mastiffs spread across the globe, but it’s quite possible that the breed’s effective population size is less than 5.




Was there one watershed moment that prompted you to take this course? Was there one dog, one incident that was a catalyst for you?

We used to film and produce our annual championship shows, so over the years we’d met a lot of Mastiffs. Many of them had died before the age of six or had suffered from serious conditions such bloat and cruciate ruptures. Through our own Mastiffs we’d experienced all the usual problems associated with the breeding of Mastiffs, such as infertility and uterine inertia. For a long time we believed that the common problems in the breed were just part and parcel of having Mastiffs. We only realized they had a likely root cause after studying population genetics and building an extensive pedigree database that enabled us to accurately assess our Mastiff’s COI (coefficient of inbreeding) values. Our watershed moment probably occurred halfway through our studies when we realized the connection between high COI values, recessive disorders, and decreased immunity to disease and infection. We had learned by then that many of the problems occurring in our breed were also occurring in other breeds that had similar backgrounds – i.e. had endured bottlenecks after the wars, and had high numbers of popular sires and high levels of inbreeding and line breeding. Coming to understand that much of the suffering we had witnessed in our breed could have been predicted was a really big moment for us. At that point the piebald case, which we were intending to continue pursing, became utterly inconsequential to us. All that occupied our minds was the fact that a high percentage of Mastiffs were getting struck down in their prime and there were things that we could be doing to greatly reduce the likelihood of this happening to them. It became very clear to us that our Mastiffs needed fresh diversity, and so we spent the next 12 months looking at our best options for getting it to them.  

What other breeds besides the Greyhound did you consider for the cross? What did they bring to the table, and why were they ultimately rejected?  

Some of the other breeds we considered for the outcross were the Bullmastiff, Cane Corso, Boerboel and some of the livestock guardian breeds (LGDs) such as the Caucasian Shepherd Dog, the Anatolian and the Turkish Malakli dog.  

We felt that using a good Bullmastiff with excellent structure would be great for not straying too far from Mastiff type or temperament, but Mastiffs and Bullmastiffs share many of the same genetic disorders and probably many of the same kinds of genes. We felt that more could be gained for the Mastiff, in terms of health, by using a breed not so closely related to it. We would still consider using a Bullmastiff down the track, but for the first outcross we didn’t feel it was the right way to go.  

Using a great-structured Cane Corso or Boerboel would have nicely infused more athleticism and also kept us comfortably close to Mastiff type but they also suffer from many of the same disorders that Mastiffs suffer from and the gains were once again not so appealing for a first outcross.  

With the LGD breeds our main concerns were for altering temperament slightly too much. We had no doubt that using a good LGD dog would give us big, beautiful pups, but we didn’t want to risk having to select against some them because they lacked docility or were showing behavior untypical for Mastiffs.


Backcrosses are not commonly done in purebred dogs, and some consider them treacherous waters.

Backcrosses are not commonly done in purebred dogs, and some consider them treacherous waters.


Who was the Greyhound sire that you used? Did you choose him for his pedigree? Any specific characteristics?

At this time we’d like to keep the identity of the Greyhound sire that we used private. His owners were kind enough to let us use their dog, and we don’t want them to have to go through what we went through when word got out that we had done a cross breeding. Perhaps when we transition into a more enlightened age we won’t have to worry about this. At this time only our puppy buyers and closest friends know who he is. We can say, though, that he is a racing Greyhound, and we chose him for his great structure, performance record, pedigree and age. He is 12 years old and in excellent health. He still goes out on morning training sessions and runs effortlessly alongside the vehicles with the younger Greyhounds. Because of his age and good health we knew that he didn’t have osteosarcoma, one of the few shared disorders between Mastiffs and Greyhounds.  

Colonel David Hancock, judge and author of several books on Mastiffs and Sighthounds, made these comments about him: “What a superb dog – what shoulders, loins, angulation at the stifle, length of rib cage and back – these Greydogges really should be something special. How wise and canny of you to find and then use him, very well done.” 
Anyone who knows David, knows that he doesn’t give compliments on dogs easily. He was truly impressed with our choice of sire.  

Is it possible for the backcrossed dogs to be incorporated back into the gene pool of registered Mastiffs — the “three generations and back in,” as the British Kennel Club permits? Or is the process more difficult than that? Does it even matter to you that your dogs are registered?

We’d love for our backcrossed pups to be allowed back into the breed so they can help other Mastiffs, but it’s very unlikely any breed club will sanction them. There is a strong belief among breeders that the Mastiff has enough diversity to get by without the need for outside intervention. The best we can hope for is that through our efforts breeders will be able to see what can be achieved for the Mastiff by outcrossing to another breed. It may pave the way or at least make things easier for others to start a sanctioned outcross project for the breed in the future.  

You mentioned that your efforts with piebald Mastiffs met with little success with the breed clubs. Can you talk more about that: What were your efforts with pieds? Were you breeding for them specifically, or just accepting them if they turned up? What kind of resistance did you encounter?

We’ve never bred for pieds; we just happened to have some occur in a litter we bred in 2012 where three of the 10 puppies born were piebalds. The sire and dam of the litter were both standard-colored Mastiffs, and we had no idea that they both carried the piebald gene prior to their puppies being born. Instead of fobbing our pieds off to pet homes, we kept two of them because they were just too gorgeous to part with. Also, we are avid lovers of Mastiff history, and anyone with a passion for Mastiff history would have to love pieds. They are found throughout Mastiff history and have been captured in portraits by many famous artists.
We did do two repeat breedings with the same parents because they were also producing the best standard-colored puppies we had ever bred.

Some people accused of us breeding for pieds because of this, but we would have done the repeat breedings whether we’d had pieds or not. We don’t breed for color. We take what we get and love all the colors that Mastiffs come in. We’ve never made any extra money on pieds and have only ever sold two: one to a dear friend in America and the other to a dear friend in Holland. To date we haven’t bred any of the pieds we kept for ourselves and it’s doubtful we’ll ever have any more of them. We easily could breed for pieds if we wanted to but it’s simply not a priority for us. We did, however, feel that it was important for us to stand up for their right to be recognized as Mastiffs.  


Piebald Mastiff puppy Rhapsody, who was born two days before the Greydogge litter, and Freddy.


Piebald-coated Mastiffs born in Australia cannot be fully registered, shown or bred from, but it’s simple enough to avoid producing pieds by breeding pied-gene carriers to non-carriers. To stipulate that pied Mastiffs may not be bred from is an unnecessary waste of all the other Mastiff genes they carry. Some of the genes lost could be the last of their kind in the Mastiff gene pool. In our view it’s a needless loss of genetic diversity, which is important to preserve within breeds.  

In Australia we follow the U.K. breed standard for the Mastiff, and the only acceptable colors for Mastiff registration are fawn, apricot and brindle. For our kennel club to allow full-registration status to piebald Mastiffs, the UK Kennel Club would have to approve the color for registration. The U.K. Kennel Club in turn lets the British breed clubs decide on acceptable colors for the breed. We wrote to the two British Mastiff clubs to ask them if they would consider recognizing the piebald coat color. Along with our request we submitted extended pedigrees for our pied Mastiffs, DNA tests results confirming their breed purity (and the presence of the piebald gene), and photos of our pieds and other purebred pied Mastiffs from America and Europe, as well as historical evidence of pieds. We never heard back from the Old English Mastiff Club but in the club’s magazine the club chairman called us “minor Antipodean breeders” and insinuated that we were breeding designer Mastiffs for money.  

With no hope for the two British Mastiff clubs unanimously consenting to recognize pieds, we started a petition for pied recognition and addressed it to the U.K. Kennel Club. It got 413 signatures, but didn’t accomplish much more than that. We might have carried on fighting, but it was around this time that we started studying population genetics, which had made us realize that there were more important things needing our attention.  

The U.K. Kennel Club does ask that all colors known to occur in a breed, whether desirable or not, be listed for registration by the breed clubs. We’re optimistic that color restrictions in breeds will one day be a thing of the past.  


The Greydogge puppies have surprisingly good bone, considering their Greyhound sire.

The Greydogge puppies have surprisingly good bone, considering their Greyhound sire.


What has the reaction from the Mastiff community about the outcross project been? How have you responded, if at all?

The feedback from the purebred community has been mostly hostile. Even people whom we thought were our friends have turned against us and have threatened to take us down (whatever that means). The Mastiff club here is warning everyone to DNA test the puppies they buy from us for breed purity. There’s been a lot of resentment about us using the Greyhound in particular; many think it was a dreadful choice. We haven’t really responded to the hostilities, mainly because we’ve learned from past experience that it’s next to impossible to reason with breeders who have no understanding of population genetics. We just try to explain things clearly when people ask us direct questions about breeding and have explanations of what we are doing/achieving on our website, video releases and Facebook pages.  

What are your F1s, or first-generation dogs, like? (In the videos they look like super-sized lurchers – the traditional term for Sighthound crosses – which indeed they are.) Do you see parts of either breed predominating? In terms of the “drag” that the Greyhound blood brings, what atypical traits do you see coming through that will need to be addressed in later generations? Narrowness of rib cage? Snipiness of head?

We could probably talk about our F1s till the cows come home, we are so proud of them! We expected them to be an even mix of Mastiff and Greyhound, and that’s exactly what they are. What we didn’t expect was their wonderful characters, their gentleness, their good nature and their laid-back manner. We had no idea how affectionate they’d be, how much they’d love sitting on the couch with us (or without us) and how good they’d be to sleep next to. We didn’t expect them to be as big as they are or to be so similar in coat and structure to our purebred Mastiffs. There’s no real narrowness anywhere on them; their structural proportions are very good for big dogs.  

Although many modern enthusiasts refuse to consider Mastiffs as hounds, historical evidence suggests that they were literally a heavy, broad-mouthed variety of hound. In medieval times they shared the hunting field with Greyhounds, and almost all our early depictions of the Mastiffs of England show Sighthound influence.  

Having our F1 crosses is like having a clean slate to work with. We feel that everything we need to create a good Mastiff is in them. In the backcrosses, we’ll mainly just be focused on getting back a little more body mass and the Mastiff’s distinctive broad muzzle.  



Reinstating Mastiff head type will be an objective for future breedings.
Reinstating Mastiff head type will be an objective for future breedings.
More than almost any other breed, the Mastiff actually has had a great degree of modern backcrossing, thinking of course to the Deer Run kennel and its reportedly ample, unorthodox use of other breeds to strike a balance between type and soundness/health. That situation worked, of course, because it was held as an open secret and was not publicly announced. Why do you think there is such resistance to the idea of planned, systematic outcrossing?
Listed below are some of the main reasons why we think there is resistance among Mastiff breeders for outcrossing to another breed: 1) Fear of loss of breed type in terms of temperament. 2) Fear of loss of breed type in terms of physical features. 3) Fear of loss of breeder’s license. 4) Fear of unwanted traits coming through generations down the track. 5) Failure to recognize that there are problems in the breed. 6) The belief that a large population means there is plenty of diversity to be had in it. 7) The belief that variations in phenotype equal useful diversity. 8) The belief that the cross or crosses supposedly used by Deer Run Kennels in the late 1970s are still providing breeders with useful diversity. 9) A mistrust of pedigree record keeping and COI analysis. 10) The belief that high COI values are necessary and good. 11) The belief that inbreeding or line breeding is the best way to achieve typical breed specimens. 12) The belief that the Mastiff always has been a pure breed.




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