Merle: Breeding Responsibly for Quality

By Alane Levinsohn

 

Merle Pom

8 week old blue merle puppy

The controversial blue merle color is a stunning swirl of black and gray that literally sparkles in the sunlight. This color is becoming more and more popular in the Pomeranian breed. There are several rules that one must follow in the quest to breed a dog of this color. Since it is a dominant color, it is an easier color to work with and requires fewer dogs to be kept than most exotic colors.

Defining the Color

Let us start by defining the color. The merle gene dilutes the base coat of the dog in a random fashion with a few exceptions. It works primarily on the black or brown hairs (i) to create patches, heavy ticking or a swirling pattern. Because it is simply a dilution gene, the real color of the dog is the base color. I will use the definitions and terms used by breeds in which merle is common such as: Collies & Shetland Sheepdogs (Sable Merles, Blue Merles), Australian Shepherds ( Blue Merles, Red/ Liver Merles.)

Blue merle – This is the classic gray/black pattern. The blue merle is actually a black or black and tan dog with the dilution gene acting upon the black areas of the coat. Pigment will be black. One or both eyes may be blue, have blue flecks or be brown. 

Merle Pom

Blue merle newborn puppies. The pattern is evident at birth.

Red, Liver or Chocolate merle – This is a chocolate dog with the dilution pattern acting upon it. This dog will have a chocolate nose and pigment and the pattern will be chocolate and silvery chocolate. One or both eyes may be blue, have blue flecks or be brown.

Sable Merle – this is a sable dog with the merling acting primarily upon the black hairs in the coat (i). In a heavily sabled dog the pattern may be very obvious, while in a lightly sabled dog, it may be imperceptible. The merling pattern is clear at birth but can fade within weeks. An experienced breeder can recognize the distinctive champagne color of the coat of an adult sable merle dog. Pigment of the dog will be black. One or both eyes may be blue, have blue flecks or be brown.

Merle Pom

This is a sable merle puppy. You can see the pattern in the black hairs at birth. When this puppy's coat started to grow, the merling disappeared and only his blue flecked eye gave away his merle heritage.

Variations – Merle can dilute black and chocolate each time it occurs including: black, black and tan, chocolate and tan, dilute black (blue), blue and tan and dilute chocolate (fawn/beaver/Isabella), sables, brindles. Merling can occur in the color areas of parti-colored dogs. Other colors (red, orange, cream) show little visual effect. One or both eyes may be blue, have blue flecks or be brown.

Developing a Strong Program

In order to develop a strong blue merle program you will need to start with an exceptional black program. Currently, the merles, like most exotic colors are lacking in type. A good black and tan program will also produce good blue merles. If your interest is in the red or chocolate merle, you must start with exceptional chocolate dogs. Using sables or oranges MAY produce blue merles, however it is less likely than using blacks, black and tans or chocolates.

Merle Pom

Adult blue merle bitch

The merle gene is a dominant gene. This means that it only takes one merle dog to produce merle puppies. Statistically 50% of offspring will be merle. Improve your chances for the color by using blacks, B&T and chocolates.

Color

Currently, most merle Pomeranians have a somewhat rusty coat color that needs to be improved. The optimal color is a medium, clear blue with a black background. The rusty color we are currently seeing may be due to the basecoat being a red/black. The best way to quickly “clean-up” the color is to use a blue/black dog. Select for clean colors, but select for conformation, soundness and type first. You can improve the shade of the color in one generation. 

The other theory is that the rusty color is the top end of the hierarchy of merle coloration (iii). Again, select for the cleaner colors, but conformation, soundness and type come first.

Things to Avoid

Avoid breeding merles to whites and creams. Many breeders think they can clean the color or lighten the color by breeding to a white or a cream, but this is not so. It is an entirely different gene. Also, more importantly, if there are offspring born who do not have black on them, it is difficult, if not impossible to tell if they are a merle or not, unless they have a blue eye. At this point, without DNA testing, we have no way to know, so they should be neutered and placed in pet homes.

Merle Pom
These two puppies were born without any black pigment. Until there is a DNA test for the presence of the merle gene, puppies born this color should be spayed or neutered and placed.

Avoid breeding brindles and merles. Mixing a brindle in will make it difficult to distinguish the merles from brindles at birth. Since the merle pattern is random, it can appear as stripes in areas. Additionally, since the current blue merle color is slightly rusty, it can appear to the casual observer to be brindle.

Most importantly, avoid breeding two merles together. If you avoid doing this, you will avoid all of the controversial potential health issues. If two merles are bred together there is a chance of producing deafness and eye problems. While some breeds have almost an entirely merle gene pool (the Catahoula Leopard Dog), we do not, so we have other breeding options. A double merle in parti-colored dogs can present a problem because it increases the amount of white on the offspring. The white spotting pattern has been linked to deafness (ii), so excess white is not desired. Prominent geneticists recommend that dogs with more white than an Irish pattern NOT be used in a merle program.

Phantom/Cryptic Merles

A phantom or cryptic merle is a dog that appears to be one color but reproduces like a merle. Any time there is the smallest spot of merling on a dog, that dog IS a merle and will reproduce like one. Offspring from each merle breeding need to be checked carefully at birth to distinguish merles from non-merles. On dogs with a basecoat of white or cream, the merling pattern shows little visual effect, if any. Remember, merle acts primarily on black hairs or chocolate hairs. IF there are no black or chocolate hairs to act on, it is very difficult to distinguish the merle. Again, these dogs should be spayed or neutered and removed from breeding programs.

Merle Patterns & Colors

The merle pattern is a random pattern, with no two dogs having the same pattern. Each is as individual as a snowflake, however there are some rules of color and pattern dominance. (iii)

The merle color comes in a hierarchy of patterns and colors. I will briefly cover color here. For more detail, see the article Theories of Coat and Pattern Dominance in Shelties - Notes on Blue Merle, Dilute and White Factor by Cheryl Anderson.

Merle Pom

Both of these shades are examples of blue merle poms.

The blue merle color comes in many shades of gray from deep, almost black to a pale almost white color. Currently we are seeing the colors at the upper end of the color hierarchy in merle Pomeranians. Most are deep gray or a rusty gray. According to the Anderson article, the order of dominance in color is (from most dominant to less dominant) Pigeon Blue: a deep color comparable to a steel wool pad, Pewter blue: a deep blue that can have a brownish cast, Powder Blue: a glacial blue, Silver: a light clear version without a blue cast , Dilute: the gray is dilute to an almost white color. In breeds where merle is very popular, the powder blue and silver are considered the most desirable shades. 

The Future

There is current research being done to locate merle in DNA. (iv) Once it is located, a test can be developed to determine merle from non-merle dogs. This test will be invaluable since once it is developed, there will be no more cryptic or phantom merles. Any dog in question can be checked and declared either merle or not. Once testing is done, dogs in question can be used with confidence in a breeding program.

The merle gene, although controversial, is here to stay. In breeds where it is common, it has become a very popular color. Any color breeding is challenging and this color is no exception. With a solid foundation of quality dogs, a discerning eye and the conviction to neuter dogs whose color is in question, it will not be long before one will walk into the show ring.

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Reference:
(i) Sue Bowling; http://bowlingsite.mcf.com/Genetics/BasGen.html 
(ii) The Veterinary Journal, May, 2003 – George M Strain, Deafness Prevalence and Pigmentation and Gender Associations in Dog Breeds at Risk
(iii) Theories of Coat and Pattern Dominance in Shelties - Notes on Blue Merle, Dilute and White Factor - Cheryl Anderson
(iv) Schmutz, S. M., T. G. Berryere, and C. A. Sharp. KITLG mapping to CFA15 and exclusion as a candidate gene for merle. Accepted by Animal Genetics, July 7, 2002. 

 
 
 

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