The pug is one of the most distinctive and easy to recognise dog breeds of all, and even people who aren’t overly familiar with different dog breeds can generally identify a pug when they see one. Whilst every pug is of course different and they can be a little variable in terms of their size, build and features as well as of course colour, most of us would still be able to pinpoint the breed of any pug we saw.
However, if you’ve seen a dog that looks like a pug but that displays an unusual colour not normally found within the breed, you might have spotted a merle pug; and if you stopped to ask the dog’s owner more about their dog and the colour it displays, you might have found that this left you with more questions than it answered!
Merle pugs are quite uncommon and unless one lives in your local area, you may never have seen one in the flesh, or have known that merle pugs exist at all. Whether or not merle pugs should exist in the first place is the cause of a lot of debate, and there is a lot more to the merle colour in pugs than just the shade and pattern of their coats.
If you are interested in merle pugs and want to find out more about them or if you have decided that a pug is the right dog for you and you want to buy a merle pug puppy, read this article first.
We’ll tell you everything you need to know about merle pugs, including how the colour was introduced to the breed, its implications, and why there is a lot of objection to breeding merle pugs in the first place.
Read on to learn more about merle pugs, including merle pug health, and how the merle coat pattern is inherited.
A merle pug is a standard pug dog like any other, aside from the distinctive colour and pattern of their coats. The merle coat type is one that can be found occurring naturally within several breeds of dog such as the Cardigan Welsh corgi and the Border collie, but it is not one that occurs naturally within pugs.
A merle coat is one that can be found in various different presentations of pattern and colour, and the term “merle” refers both to the shade of the coat and the distribution of the colour in patches across the coat.
Merle colour in pugs occurs due to a specific gene that causes mottled patches of colour that are often blueish or blue-grey in colour, across a coat that is otherwise all one colour or patches of two distinctive colours, which is known as piebald.
As well as causing the dog’s coat to have an interesting and often very beautiful colour and pattern distribution, the same pattern may also be present across the dog’s skin as well, and may also be accompanied by blue eyes, or the two eyes being different colours.
However, merle pugs may inherit more than just a skin and coat pattern and distinctive eyes along with the merle gene – they may also inherit a number of hereditary health issues too, which can go hand in hand with the inheritance of the merle pug colour.
Whilst not all merle pugs will suffer from health issues as a result of their unusual colour, a significant enough percentage do for this to be of great cause for concern within the breed as a whole.
The merle colouration in dogs occurs due to the presence of certain genes that result in this type of colour and pattern effect, and these specific genes are referred to as “M” genes. Whilst “M” genes can and do occur naturally in several dog breeds such as the Cardigan Welsh corgi and the Border collie as mentioned above, they are not present in most pedigree dog breeds; including the pug.
Breeding standard pedigree pugs with each other will never result in the birth of a merle pug puppy, because the merle genes simply do not occur naturally within the pug breed.
This means that in order to produce merle pugs, the “M” genes have to be introduced to the breed line from another dog breed, which requires one or more of the dog’s ancestors to have carried and passed on these genes. Ultimately, a merle pug will have at least one (and maybe more) ancestors within their bloodline that were either of another breed of dog entirely, or that were pug crosses with the “M” gene contributed by the other breed within the mix.
Whilst the vast majority of merle pugs will look just like any other pug because they have been selectively bred to retain the pug appearance aside from their colour, they are not technically considered to be purebred pugs, due to the historical introduction of the merle gene.
The colours that fall within the pug breed standard are clearly defined by the Kennel Club, and indicate the colours that occur naturally within dogs of the breed and that have no negative implications for the health of the dogs that possess them.
The acceptable colours for pedigree pugs in the UK are:
There is also a fifth option offered to breeders registering new pug puppies, which is referred to as “colour not recognised.” This designation enables pug breeders that have produced pugs in colours other than the four standard ones to register their puppies so that they receive their pedigree paperwork and can be sold as registered pedigree dogs, whilst reflecting their non-standard colour.
This is the appropriate option to register pugs in colours that fall outside of the breed standard, such as brindle or white – but merle pugs cannot be registered as an unregistered colour even so, and we will explain why this is later on.
As we mentioned earlier on, the merle colour is not one that appears or has developed naturally within the pug breed, and so it is worth explaining what makes a merle pug and how some pugs come to display the merle colouration.
Within the pug breed, the merle genes are introduced to the breed line by means of outcrossing with other dog breeds that do carry and express the merle gene to result in the merle coat colour.
This will probably have occurred a long way back in the dog’s ancestry, resulting in pugs that may well have a traceable ancestry going back several generations and involving dogs that were all purebred pugs, but go far enough back, and you will see the genetic input for merle from another breed.
Genetic mutations can and do happen spontaneously in nature now and then across all manner of species and can result in some interesting and sometimes beautiful results. Sometimes they even help to give the animal in question an evolutionary advantage, but they can also result in problems too, such as health and conformation defects that can have a negative impact on the animal’s health and chances of survival.
Such harmful genetic mutations often result in an inability to reproduce or a shortened lifespan that reduces the chances of such genes being passed on, and most genetic mutations are of the autosomal recessive type, which means that both parents must carry them before their offspring will also inherit them. However, when a mutation is dominant, this means that all or most of the animal’s own offspring will also inherit the same trait, and this is the case for merle in pugs.
The merle gene is one that has been introduced to certain pug breed lines rather than one that manifested naturally, but regardless of how merle genes were introduced to pug breed lines in the first place, the end result is the same.
Dominant genetic traits can quickly spread throughout a breed’s population, from just one parent animal that carries them.
The merle coat colour is inherited by means of autosomal dominant heredity with incomplete penetrance. This means that a dog only needs one of their parents to display the merle colour in order to stand a high chance of inheriting it themselves, and this makes the merle gene one that is easy to pass on from dog to dog, without the need to keep back-crossing to other unrelated merle dog breeds to maintain the colour.
However, the incomplete penetrance of the merle gene means that it is not guaranteed that having one merle parent will result in their pups also being merle; and a litter may contain both merle and non-merle pugs, if this is the case.
A pug that has two merle parents will always display the merle colour; this is known as double merle. However, as well as guaranteeing the merle pug colour, crossing two merle pugs to produce a guaranteed litter of merles also greatly increases the chances of said double-merle dogs inheriting a wide range of serious health issues that have a significant impact on the dog’s quality of life. We will expand on this in more detail later on.
Here’s how the heredity of the merle colour in pugs works:
There are two different types of merle genes, known as “M” or “big M” and “m” or “little m” respectively. Whether or not a pug inherits the merle colouration depends on what combination of merle genes they inherit.
The merle colour genes are not genes that occur naturally within purebred pug breed lines, but have been deliberately introduced as part of selective breeding programmes and then maintained and passed on as part of planned mating matches to reproduce the same perceived desirable traits.
This means that some pug breeders seek to produce distinctive breed lines to serve the continual demand for pug puppies, and particularly, pugs that display rare or unusual traits.
We don’t actually know when the first merle pugs appeared or whether they were bred deliberately to introduce the merle colour or happened as the result of a mating mis-match with another dog, but pugs are really popular dogs in the UK – the third most popular dog breed overall, in fact – and demand for unusual, rare and interesting pugs is particularly high.
As pugs have gained traction and increased in popularity within the UK over the course of the last couple of decades, so too have breeders been incentivised to produce dogs to meet this demand, and to produce dogs that possess a certain appearance that puppy buyers want.
This has resulted in a number of changes across the wider pug breed over the course of the last few decades, and today’s pugs are rather shorter, stockier and flatter-faced than their historical counterparts. Pugs with extremely exaggerated flat faces, prominent eyes and other distinctive traits are often in particular demand among puppy buyers, despite the health complications that can accompany such traits, as are those that may display unusual colours or other distinctive features.
As merle pugs often get a lot of attention, sell quickly and command high prices, more and more breeders have come to consider producing them, which has resulted in a small but thriving market for merle pug dogs in the UK.
The potential health issues that can be inherited by merle pugs are of particular concern within the breed as a whole, but before we look at these merle-specific health issues in more detail, it is first wise to talk about pug dog health in general.
Looking at the health and wellness of the pug breed as a whole, these small and very popular dogs are a very high-profile breed in terms of the range of health issues that can be found within the breed, and their level of prevalence across the breed as a whole.
A lot of the modern pug dog health problems that pose a threat to the breed have actually only been introduced to the breed in significant numbers over the course of the last few decades, as a result of selective breeding.
Selective breeding is the practice of choosing specific dogs to mate with each other, in order to try to reproduce or eliminate certain traits that they possess in their subsequent offspring. Whilst selective breeding is a standard, accepted and even necessary practice within pedigree dog breeds, it can also cause problems if undertaken without due care and consideration, or if it is deliberately intended to reproduce traits that may also result in health problems.
Within the pug breed specifically, there are a large number of hereditary health problems that have now become widespread across the breed, and that affect significant numbers of the dogs within it, regardless of colour.
These include BOAS or brachycephalic obstructive airway syndrome, which results from the breed’s shortened muzzles and flat faces. The protruding eyes that accompany exaggeratedly flat faces can also result in both conformation issues that affect the functions of the eyes, and also makes them more susceptible to injuries and damage.
Spinal issues, neurological issues such as pug dog encephalitis and a range of other problems can also be found within the modern pug breed, and this is also a breed that tends to be fairly well-padded and stocky, and which can easily become obese.
It is important to note that there are many healthy pugs in the UK and not all pugs have serious health issues or even any notable health issues at all – but the breed as a whole is one that is widely associated with a large range of prevalent health issues. You can find out more about these within our general guide to pug health.
A merle pug may well inherit one or more of the common pug health issues outlined above, but the main reason for the controversy surrounding the existence of merle pugs at all comes from the inherent risks for health issues that specifically accompany the merle gene in pugs.
Again, the potential for merle-specific health issues in pugs does not automatically mean that a merle pug will exhibit them, but it does introduce a further element of risk into what is already a complex breed where health is concerned.
The genes that lead to merle coloured pugs come with an increased risk of merle pugs having hearing problems; these may affect either one or both ears, and range from total deafness to partially impaired hearing. Vision problems are another issue that can be found in some merle pugs, and again, this may result in full blindness in both eyes, or less acute vision problems.
Merle colouration may also result in poor melanin production across the merle areas of the skin, which can in turn lead to merle pugs being more prone to suffering from sunburn, skin problems, and hypersensitivity to sunlight.
Such merle-related health issues are present from birth, and are a type of congenital defect. It is important to note that not all merle pugs will display one or more of these health issues, but the risks of these problems occurring are high enough to ensure that the merle colour in pugs is considered to be harmful to the wider health of the breed as a whole.
As we mentioned earlier on, breeding one merle pug with a standard colour pug is highly likely to result in merle puppies, but this is not guaranteed; but if you breed two merle pugs with each other, their offspring will all inherit the merle colour, and this is known as double-merle.
Whilst the merle genes in general are considered to increase the risk of health issues in pugs, things kick up a gear when it comes to double-merles, and double-merle pugs have a much higher risk of inheriting health issues along with their colour.
In fact, it is rare for a double-merle pug to be totally healthy and not suffering from any colour-related health issues, and around a quarter of double-merle dogs will be born both completely deaf and completely blind, often with abnormally small or malformed eyes.
This means that breeding or buying double-merle pugs should be avoided at all costs, regardless of your viewpoint on the merle colour in pugs in general.
There is a lot of debate over the general condition of the pug dog breed as a whole in terms of its health, breeding practices and modern norms, due to the prevalence of health issues and conformation defects within the breed.
The Kennel Club is the UK’s umbrella organisation for pedigree dog breeds and dogs as a whole, and serves as a central registry for pedigree puppies of all breeds, as well as being the formal recognised organisation for pedigree dog development and improvement. As part of this, the Kennel Club (alongside of a number of individual breed-specific organisations and clubs) monitors the health of all registered dog breeds, and works to maintain breed standards and show policies that are designed to place the welfare of dogs, improvement of the breed and the health of the dogs within it as the most important priorities.
How effective the Kennel Club is at achieving this is a matter of a lot of debate in itself; many people think that the Kennel Club doesn’t go far enough towards catalysing improvement within the pug breed, promoting good health, and penalising breeders who produce and show unhealthy dogs.
However, the Kennel Club considers the presence of the merle gene in pugs to be one that not only falls outside of the breed standard, but that is also harmful to the health of such dogs and the improvement of the breed itself to the extent that they have a set policy of refusing pedigree registration to merle pugs full stop.
This policy was introduced in consultation with the Pug Breed Council, which is the pug’s formal breed-specific advocacy organisation, and which works closely with the Kennel Club in important matters such as health and breed improvement.
The Kennel Club’s policy on refusing registration to merle pugs was drawn up in association with the Pug Breed Council and their affiliated regional clubs, and none of these organisations recognise nor support the presence of merle pugs.
This means that a merle pug cannot be registered with the Kennel Club or recognised pug breed clubs, and that even if they appear to have a full pug pedigree ancestry, they cannot receive paperwork to this effect nor be formally recognised as pedigree pugs.
The Kennel Club cites the increased likelihood of eyesight and hearing problems in merle pugs as the reason behind this, and states that neither merle pugs bred in the UK nor those imported from abroad are eligible for pedigree registration.
Towards the start of our merle pug guide, we mentioned the “colour not recognised” option that can be used by pug breeders to register dogs of the breed that are pedigrees but that do not appear in one of the four standard pug dog colours.
However, even though the “colour not recognised” option was introduced to enable pugs in non-standard colours to be registered as pedigrees, this designation still cannot be used to register a merle pug. This is because the Kennel Club specifically states that merle pugs cannot be registered with them; and there is no way to get around this or to circumvent this restriction honestly.
As we have explained, there is no provision made for a merle pug to be registered with the Kennel Club, and no way for a breeder to register a merle pug in a way that is all above board.
However, some merle pug breeders still attempt to circumvent this restriction to register their own merle pug puppies, and there are a number of reasons why they might attempt this, and in a number of different ways.
If a puppy is not a registered pedigree, they cannot be sold as a pedigree, which usually means that the sale price that can be commanded for them is lower than it would otherwise be. Additionally, any offspring bred from a non-registered pug dog cannot in their turn be registered with the Kennel Club either, even if the other dog in the mating match is registered and the puppy has a traceable ancestry of pugs going as far back as you can see.
This means that some pug breeders attempt to register their merle pugs with the Kennel Club despite the restrictions, and they often get away with it as puppy buyers are rarely fully conversant with the ins and outs of pedigree dog breed registration, and the restrictions placed on merle pugs.
If a merle pug breeder claims that their puppies for sale are registered pedigrees, there are a few different possibilities for what is going on.
If you ever see a merle pug puppy in the UK advertised as being a Kennel Club registered pedigree dog, this statement is untrue or potentially, fraudulent if the dog has been falsely registered as another colour. Should you spot such an advert here on Pets4Homes, please use the “report” link within the advert to let us know, and we will take the appropriate action.
There are a number of other self-declared “breed registries” that have been set up independently by individuals and organisations that are totally unrelated to the UK Kennel Club (or any other recognised kennel club) and that permit a much wider spectrum of dogs to be registered and receive their own version of pedigree paperwork.
Some such registries are designed to support up-and-coming dog breeds or established breeds that are not currently recognised in the UK, but others are designed to enable breeders of questionable or contentious dog types (like merle pugs) to register such dogs and gain formal-looking paperwork as part of this.
The UK Kennel Club is by no means the only reputable dog breed organisation in the world and there are several other widely accepted authority bodies that register dogs from other countries and internationally (Like the FCA, the largest canine organisation in the world – which also doesn’t recognise merle pugs). However, many other apparently plausible registries are little more than shill operations designed to assist unscrupulous breeders to sell puppies. These registries in turn profit from the fees paid by such breeders to “register” their dogs and attain paperwork for them.
If a merle pug breeder claims that their dogs are registered pedigrees, ask them first of all what authority they are registered with, and research it independently. If they claim that their dogs are registered with the UK Kennel Club, bear and mind that this is either an outright lie, or was achieved by means of fraudulent registration.
If you find that the organisation the breeder has registered their merle pugs with is anything other than the UK Kennel Club itself or another equivalent international breed registry like the AKC (American Kennel Club), bear in mind that this paperwork is essentially meaningless, and does not replace or surpass Kennel Club registration.
Interestingly, the American Kennel Club is even more restrictive than the UK Kennel Club when it comes to recognised pug colours – the AKC recognises only black and fawn colours, and the presence of any other colour at all (including the UK-recognised apricot and silver colours) is cause for disqualification.
The correlation between merle colouration in pugs and their associated health issues is of course the main reason behind why merle pugs are considered to be problematic and why their very existence is a point of great contention, but there are a number of other elements to the argument too.
As mentioned, the pug dog breed as a whole is one with a large number of health issues that can be found within it, and the added element of merle only increases the risk of an individual dog with the merle colour suffering from one or more issues, either relating to their colour or otherwise.
The pug dog breed is a fairly high profile on in terms of its public image relating to health specifically, and the fact that some breeders knowingly exacerbate the risks by breeding merle pug dogs that might realistically inherit an additional health issue only worsens public perception of the breed and the people that breed pug dogs.
The practice of deliberately breeding dogs that fall outside of the breed standard when such a change is not undertaken with the intention of improving the breed or its health is in itself widely frowned upon and formally discouraged, and when such a practice can actually have a negative impact on the dogs in question, it is considered to be even more irresponsible.
Producing dogs solely to encourage heredity of a specific physical trait that has no benefit to the dog and that may be harmful is also considered to be very poor practice on the part of the breeder. Breeding merle pugs directly breaches the pug breeder’s code of ethics, as set by all of the responsible pug dog breed organisations and clubs within the UK.
Additionally, because the merle gene is a dominant one that will quickly spread through a breed population if left unchecked, the merle gene’s presence in some pug blood lines is considered to pose a threat to the future development and improvement of the breed as a whole, and maintenance of the breed standard.
The fact that merle pugs have elevated risk factors for inheriting health problems is something that many people who find this colour eye-catching and appealing don’t even realise, and people seeking to charge high sale prices for merle pug puppies will rarely share this information with prospective buyers.
Whilst it is entirely possible that a merle pug will have no health issues at all relating to their colour, simply buying a merle pug increases demand for them and this results in further merle litters being bred – some of which will be unhealthy.
Promoting or supporting the practice of breeding dogs that have a high chance of inheriting a totally avoidable health issue is something that no breed club, puppy buyer or responsible breeder will get behind, but all too many prospective pug buyers are poorly informed about the breed as a whole, much less specific colour-related issues within rare and unusual colours.
Merle pugs for sale often command much higher prices than lovely examples of standard-coloured pugs, reflecting their perceived rarity compared to demand for them. Again, this artificial price inflation based on a trait that is ultimately harmful to the breed as a whole is something that responsible pug breeders strongly discourage.
Because merle pugs cannot be registered with the Kennel Club, they are not eligible to enter formal Kennel Club dog shows or Kennel Club affiliated breed dog shows either.
Kennel Club dog shows are intended to identify and reward the best examples of the breed that is being exhibited and as such, this means the dogs that conform most closely to the set breed standard. Merle pugs fall outside of the breed standard and so could not be rewarded in the show ring even if they were entered – and if an unwitting puppy buyer arrived at a Kennel Club show to show a merle pug, they would be automatically eliminated, and the pedigree paperwork for the dog that enabled them to be entered in the first place would be revoked.
Merle pugs cannot be entered in pug breed club shows either, due to the united stance presented by the Kennel Club and responsible pug breed clubs on the presence of merle pugs.
However, a merle pug can enter an informal fun dog show just as any other dog can, although they will never be able to compete in Kennel Club breed shows.
Because the merle colour doesn’t occur naturally in pugs and because the breeding of merle pugs is strongly discouraged and penalised by means of the refusal of pedigree registration, there are not many pug breeders who deliberately breed merle pugs.
Merle pugs are often advertised and described as being highly unusual, very rare or otherwise in such a way as to make them appear special, desirable or highly valuable, and they are usually advertised at a higher than normal price as a result of this.
But how rare and uncommon are merle pugs really? Well, at the time of writing (January 2019) there were a total of 524 pugs advertised for sale here on Pets4Homes, and just 10 of them are advertised as being merle.
This represents just under 2% of all pugs advertised for sale at the moment, and so it is certainly fair to say that merle pugs can be referred to as rare. But this does not mean that they are better than or somehow superior to other pugs, only that the people that breed them are prepared to go out on a limb and accept all of the negatives and disadvantages of breeding merle pugs in order to turn a profit.
Any dog that is described as rare, unique or highly unusual is likely to attract a higher than average sale price if they are in demand among puppy buyers, and merle pugs are no exception.
At the time of writing, the average advertised price for pugs of all types on Pets4Homes is £901 for a Kennel Club registered pug, and £738 for a non-Kennel Club registered pug.
When it comes to merle pugs for sale, the prices can vary quite significantly from dog to dog, ranging from lower than the cost of a standard pug (which may reflect the presence of merle-related health issues) up to well over the £2,000 mark.
Choosing to buy a dog of any type is not a decision that anyone should enter into lightly, and when it comes to complex breeds like the pug that often exhibit health and conformation problems that can impact upon the dog’s quality of life and longevity, you should take even more care over your decision.
All too many pug buye