why are there so few breeders of blue merles

[klw]

hi, just curious as to why there are so many breeders out there of shelties but hardley anyone breeds blue merles,why is this ? can someone tell me ? i heard there can be genetic problems with merles is this the reason why ? 

cheers

[Diva]

Breeding Merle to Merle leads to vision and hearing problems in pups. Statistically a quarter of Merle to Merle offspring will have two copies of the Merle gene and the associated health problems. If you google you will easily find info on that.  Merle mated to non-Merle is, as I understand it, not a problem and most breeders wouldn’t knowingly do a double up, unless they just don’t understand or don’t care. It is a dominant gene so should be easy to avoid doubling on. However some  Merles have the pattern ‘hidden’ by a different gene which prevents the visible expression of black in  the coat or are ‘cryptic’ where the Merle pattern only shows on a small part of the dog, which could lead to it accidentally happening. There are also several different genetic forms of Merle identified now, and I don’t know if they all have the same level of issue. 

 

I don’t know if that is why Shetland sheepdog breeders aren’t breeding them - did you ask them directly why? It does bother me that breeds that never had the pattern in their breed are now cropping up with it, cross-bred into the breeds by dodgy breeders after the money because it is pretty and it sells. It has always been in Shelties as far as I know,  so not the same issue for their breeders, although maybe they want to avoid breeding dogs that might be sought after for cross-breeding for profit.  Not my breed, just interesting genetics. And ethics. 

Edited September 10, 2018 by Diva

[Dogsfevr]

Because they often require more effort to get that colour and then a correctly marked one ,there still breed but sable is the most common colour.

This is a common factor in many breeds where certain colours just don’t appear in all litters unless in the lines .

Like many factors you can’t breed the same dogs over and over so unless people are importing new lines that carry the Merle then people are happy to just have the sables .

There are other colours that appear less then the Merle’s and again when people are breeding its generally not about the colour but the future 

[sandgrubber]

That's a good thing.  Blue Merle is an unhealthy recessive mutation.  If both sire and dam carry the gene it's likely to have serious consequences for, on average, 1/4 of the puppies. 

[Diva]

7 hours ago, sandgrubber said:

That's a good thing.  Blue Merle is an unhealthy recessive mutation.  

Merle is not recessive. It is an autosomal incomplete dominant with several variants. Not everything causing health problems is recessive.

 

Genomia

UCDavis

Edited September 11, 2018 by Diva

[Rebanne]

ethical breeders don't breed for colour, they breed for sound dogs, they choose what dog will complement their dog. Colour is the last thing, or should be, chosen

 

[sandgrubber]

3 hours ago, Diva said:

Merle is not recessive. It is an autosomal incomplete dominant with several variants. Not everything causing health problems is recessive.

 

Genomia

UCDavis

Thanks for the correction... I wasn't thinking 

[PossumCorner]

Thought this had all been covered when you asked it in your other thread klw.

[persephone]

previous question

merele is a desirable marking for dogs ... and many have been produced because of this , sadly only produced FOR the markings/colours . 

klw... take yourself to some meetings/shows & meet & greet some shelties & their owners/breeders   This will enable you to much better see different lines & what they have to offer you ..size/colours/coat.....temperament   ;) 

[ricey]

Interestingly, merle is the only unacceptable colouring for pure bred American Pit Bull Terriers. It seems that ethical breeders of the APBT recognised the problem with breeding purely for merle earlier than some other breeders.

 

ricey

[klw]

hmmm interesting facts from everyone on here very helpful thanks 

[sandgrubber]

On 9/12/2018 at 1:14 AM, ricey said:

Interestingly, merle is the only unacceptable colouring for pure bred American Pit Bull Terriers. It seems that ethical breeders of the APBT recognised the problem with breeding purely for merle earlier than some other breeders.

 

ricey

Merle is pretty rare in most breeds. I don't think it is accepted in any gun dog, hound or terrier breed.  Not sure about other groups.  Happy to be corrected. 

[asal]

On 13/09/2018 at 7:00 AM, sandgrubber said:

Merle is pretty rare in most breeds. I don't think it is accepted in any gun dog, hound or terrier breed.  Not sure about other groups.  Happy to be corrected. 

A well marked Merle is a glorious dog.  BUT its breathtakingly hard to get. my brother bred Shetland sheepdogs and Merle was his favourite of the colours but its far far easier to get a great sable or black and tan than a well marked Merle.  There are no health problems with a single gene Merle. but as others have said they should never be bred merle to merle due to the tragic results to any double Merle puppies... the gene that gives the Mexican hairless is also a lethal in double dose. although in that case the puppies do not survive so its self limiting in that respect.

 

spotted this, interesting read even if its not discussing Merle, it is discussing in this case a lethal that is actually selected for

 

"Hairlessness

There are four hairless breeds of dog - the Mexican Hairless (Xoloitzcuintle), Peruvian Inca Orchid, American Hairless Terrier and Chinese Crested Dog.

The Xolo, Inca Orchid and Chinese Crested all have dominant hairlessness, so they only need one copy of the gene to be hairless. In fact, all hairless dogs of these breeds are heterozygous for hairlessness, because it is one of the only known examples in dogs of an embryonic lethal gene. This means that a homozygous dog (one with two copies of the hairless gene) will be re-absorbed into the womb. 
Because all hairless dogs of these breeds are heterozygous, breeding a hairless dog to a hairless dog will result in some puppies which miscarry (the doubles), some which are normal hairless dogs (the singles), and some which are not hairless at all. Remember our Punnet squares for the merle gene? Mm x Mm results in one MM (double merle), two Mm (normal merles), and one mm (non-merle). This is the same for hairless dogs. 
The coated dogs which appear in hairless litters are often not allowed to be shown. The exception is the coated Chinese Crested, which is known as the "powderpuff" variety, and is accepted by kennel clubs.

The American Hairless Terrier is very unusual indeed, because it shows the only known example of recessive hairlessness in dogs. Recessive hairlessness does just what it says on the tin - a dog must have two copies of the gene in order to express it. It is not a lethal gene, unlike dominant hairlessness, and because all hairless AHTs are homozygous, coated puppies will never appear when a hairless dog is bred to another hairless dog. 
Despite the gene being recessive, currently coated dogs do still exist in the AHT breed. As the breed is fairly new, outcrosses are done to Rat Terriers to improve the gene pool. The coated puppies from these breedings (which would all be hairless carriers) can then be bred back to hairless dogs to produce 50% hairless puppies. 
American Hairless Terriers are also all born with fur - however the hairs on a genetically hairless puppy fall out within a few months. This is because one of the alleles responsible for producing them is faulty, so the hairs are not formed properly. Most recessive alleles such as this are technically faulty, which is how they work as recessive - when the dog has only one copy of the faulty allele then it can use the healthy copy to produce the usual protein/phenotype (as it still has the correct information to do this), however when both copies of the allele are faulty then there is no healthy copy to fall back on, so the protein in question cannot be produced, or is not correctly produced, resulting in the recessive phenotype. A recessive hairless dog cannot produce the correct proteins for healthy fur, a recessive dilute dog cannot produce the correct proteins for black hair, and so on. This does not necessarily mean that there is anything "wrong" with the dog, as most of the locii discussed on this site affect only coat colour/type and not health or temperament. Of course, recessive genes on other locii do often cause health problems. You don't want a faulty recessive gene in the locii controlling blood cell production, for example!

However, both types of hairlessness do come with some associated health problems (not necessarily genetic). These are mainly skin conditions and allergies, and obviously, dogs with no hair are highly likely to get sunburn and skin cancer unless they are protected from the sun. Dominant hairlessness can also cause tooth problems (usually less molars than normal).

[asal]

found this. my brother never had any problems with his but maybe he was lucky?

 

although there is deafness problems in Dalmatians and some cattle dogs neither carry the Merle gene.

 

 

 

• PetHelpful»
• Dogs»
• Behavior

The Double Merle Dog and the Dangers of Merle-to-Merle Breeding

Updated on September 1, 2017

Sophie Jackson 

 more

Sophie has been a freelance writer since 2003. She is passionate about history, the natural world, and her three dogs.

Contact Author

Red Merle Australian Shepherd puppy | Source

Introduction

In certain breeds of dog there is a coat pattern known as 'merle'. It is sometimes referred to as a colour, but is in fact due to a gene that alters the way pigment appears in the dog's coat. The merle coat pattern is popular because it is unusual and very unique, with each merle dog having a different coat pattern. But there are health problems associated with the merle mutation and the risk of these problems occurring increases when two merle coated dogs are mated together. The resulting litter of puppies has a high chance of containing 'double merles' or 'lethal whites', dogs that have very little or no colour to their coat at all. Double merles are highly likely to suffer from eye or ear deformities (in some cases both) which at the most extreme can result in complete blindness and deafness. Needless to say, the deliberate breeding of double merles causes a lot of controversy in the canine world and certain official bodies (such as the Kennel Club in the UK) have clamped down on the practice, refusing to register dogs that are a result of merle to merle breeding. This article explores the world of double merle genetics, the breeds affected, the health issues and the wide range of debates currently ongoing concerning the breeding of double merles.

Blue merle Shetland Sheepdog (sheltie). Commonly merle dogs will have at least one blue eye, but in this example, due to the tan markings on the face, both eyes are brown. | Source

What Is a Merle?

A dog with a merle coat is characterised by having patches of hair with diluted pigment (colour). Though a variety of merle colours are referred to by breeders and dog owners, the two most commonly seen types of merle are blue merles and red merles. Blue merles are, in fact, grey. They appear like a tri-colour dog (black, white and tan), but with patches of the black appearing 'faded' or grey. Similarly a red merle will have faded patches of red and will often look more mottled than the blue merle. While all of the breeds with the merle coat pattern produce blue merles, only certain breeds produce red merles. The strength of the other colours in the dog's coat (tan and black, or red and tan) can vary as well, with some merles appearing to have extremely pale colouring all over, while others can have quite strong patches of colour. Blue merles with no tan markings at all are known as bi-blues, but a red merle does not necessarily have to have tan markings.

Merles commonly have blue eyes. Sometimes they have one blue and one brown eye. They can also, on occasion, have two brown eyes. Sometimes dogs may appear to have normal coat colouring but are in fact merles and will produce puppies with the merle colouration. These are known as 'cryptic merles', but the exact reason why such dogs do not display the merle pattern remains unknown.

The merle gene is usually dominant, so a merle dog will have inherited the gene from one of its parents. While a non-merle dog (unless a cryptic) will have inherited no merle gene. In the diagrams and examples that follow (M) refers to the merle gene, while (m) refers to a non-merle gene.

For example, in a litter of mixed colour puppies the non-merles will be (mm), while a merle will be (Mm), meaning it has inherited one merle gene and one non-merle gene. This is deemed the 'safe' or responsible way of producing merle puppies.

A mixed litter of puppies with non-merles (mm) and merles (Mm) | Source

Health Problems Associated With the Merle Gene

There is scientific evidence to suggest that the merle gene may be linked to a higher rate of ocular (eye) or auditory (ear) problems. A 2006 paper on the merle gene first published by the National Academy of Sciences of the United States of America attempted to identify the gene in dogs that caused the merle pattern. Among their findings they recorded research on deafness in Dachshunds with the merle gene. One study reported 36.8% of Dachshunds with the merle coat pattern (Mm) suffered hearing problems ranging from mild to complete deafness. While none of the control group of non-merles (mm) had any hearing issues. [Audiometric findings in dachshunds (merle gene carriers)]. Another study [Light microscopy studies of the cornea of Merle dachshunds] found that merles had a "significantly greater" frequency of eye abnormalities than non-merles. Other studies cited by the article found that the merle gene was associated with skeletal, cardiac and reproductive abnormalities, but there is far less conclusive evidence for this.

The same study found that in Shetland Sheepdogs a mutation of the pigmentation gene known as Silver (or Silv) is probably responsible for the merle pattern. The exact function of Silv and how it affects pigment is unknown and remains controversial. Small studies of other breeds that can have the merle pattern found that they all had the mutated Silv gene.

Another study published in the Journal of Veterinary Internal Medicine in 2009 set out to discover if there was a link between increased deafness and the Silv gene. The study examined 153 merle dogs, and found that over 8% of the study group had some form of deafness. The study concluded that merle dogs had a higher risk of deafness compared to many dog breeds, but not compared to dalmatians and white bull terriers (which have high rates of deafness thought to be linked to their white pigmentation).

Limited research has been done into the links between the merle gene and eye problems, though a great deal of anecdotal evidence is presented on the subject. There may be a link between pale coloured eyes and eye problems, but so far the scientific research to back this claim has not emerged in the public domain.

[klw]

thanks asal that was a great read !!! i feel im now an expert in merles

[Dogsfevr]

American Cocker Spaniels can come in a Sable Merle colour .
Dapple Dachshunds is a merle

[persephone]

double merle breeding ? don't do it . 
One can end up with a beast like this - hearing is fine ..except for sound location ..that's fairly casual . 
sight is not bad..but eyes are malformed..one in particular ....
In his litter were  1 red, 1 black   with dark eyes,(both with white collars/sox) 2 dark blue merle each with 1 blue eye

..and Pudden . he is mine .

[cowanbree]

I am a sheltie breeder, mainly tris with the occasional blue litter and I can tell you if bred responsibly merles are just as healthy as a sable or tri. It is only when you breed blue to blue that you risk health defects and those health defects are obvious at birth.

 

To answer your orginal question,  not many breed merles because it is so difficult to breed  one suitable to show. Not only do you have to have a sheltie correct as per the standard but then you have to consider markings. Additionally the choice of mates is quite limited as you usually only mate tri/blues although occasionally a tri factored sabke could be used.  You have to be very hardy to breed merles.

[klw]

thanks everyone that was great !!! i just love this colour but now i am satisfied in my quest to find out why theres not many,my mind is at ease

many thanks to you all

Edited October 9, 2018 by klw