Merle (dog coat)
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Merle is a genetic pattern in a
Description
Merle can affect all coat colors. The merle forms of brown are usually called "red" (though this is not correct; red and brown are genetically different), and black is called "blue" as lighter patches of black are formed throughout the coat and look slightly blue in color. Dogs who are recessive red can still be affected by merle, but the patches are either hardly seen or, if the dog is a clear recessive red, are not visible at all.
In addition to altering the base coat color, merle also modifies eye color and coloring on the nose and paw pads. The merle allele modifies the dark pigment, resulting in eyes or
Breeds
Merle is a distinguishing marking of several breeds, particularly the
Merle is sometimes introduced to other
Genetic basis
The merle allele is actually an
In January 2006, scientists at Texas A&M University announced the discovery of a mobile genetic unit called a retrotransposon, responsible for the various merle mutations in dogs.[15] Merle can be tested for and identified through DNA.[16]
A phantom merle or cryptic merle is one with such small patches of merling, or none at all, that it appears to be a non-merle.[17] This is commonly seen in dogs who are recessive red, clear recessive reds in particular, though patches can still be seen in certain red dogs.[18] In America, a dog with the phantom merle coloring is sometimes described as being "cryptic for merle". A cryptic merle bred to a merle may produce merles, cryptic merles or non-merles, depending on whether the parents were heterozygous or homozygous for the merle alleles.[19] Another mutation for cryptic merle has been identified by Dr. Helena Synková, and has been given the working name of "atypical merle". It is recommended that if a breeder is unsure if their dog is merle or not, that they be tested for the merle allele lengths.[8]
Modifiers
Certain modifying genes work in tandem (co-dominate expressive) with the merle alleles to create a completely different look to the pattern.
Often mistaken for a "double merle", a harlequin merle (or just harlequin), is a
In 2018, a published paper identified six general categories of merle alleles that affect (or do not affect) the final coat color depending on the length of the SINE insertion within them.[21]
Health issues
Dogs with two copies of some versions of the merle allele (called "double merle") have an even higher probability of being deaf and with vision impairments.
The suppression of pigment cells (
Ocular defects
Dogs who are homozygous for certain merle alleles often have visual and auditory deficits. Currently no studies have been done to prove whether or not the merle gene affects the eyes, causing blindness.
Auditory defects
In one study of 38 dachshunds by a German researcher, partial hearing loss was found in 54.6% of double merles and 36.8% of single merles. 1 out of the 11 (9.1%) double merles was fully deaf while none of the single merles were.[26] Another study done by Texas A&M University found that of 22 double merles, eight were completely deaf and two were deaf in one ear. Of 48 single merles, one was deaf in one ear and none were completely deaf.[26] In another study of 70 dogs, 15 of them Catahoula Curs, 4 of the Catahoulas were deaf, while 86% of the double merles of other breeds were deaf.[26]
Deaf and/or blind dogs can live well with proper care. Various internet groups are dedicated to supporting carers of such dogs. Deaf dogs can compete successfully in agility.[27]
See also
- List of dog coat patterns
References
- ^ Schmutz, Sheila. "Schmutz - Merle coat color genetics". Sheila Schmutz. Retrieved 28 October 2011.
- ^ a b Presberg, Carole. "Recessive Red Merle Border Collie". Carole Presberg. Archived from the original on 21 November 2011. Retrieved 28 October 2011.
- ^ McDonald, Lisa. "Aussie Eye Color". Lisa McDonald. Archived from the original on 7 October 2011. Retrieved 28 October 2011.
- ^ "Merle Coat, mottled paw pads". Perfect Peks Kennel. Archived from the original on 3 March 2011. Retrieved 28 October 2011.
- ^ Born, Charles. "Merle Color in Cocker Spaniels". American Spaniel Club. Retrieved 20 April 2018.
- ^ "The Double Dapple". The Dachshund Magazine Online. Retrieved June 25, 2007.
- ^ "Chihuahua Club of Canada - Merle Breeding Ban". Chihuahua Club of Canada. Retrieved 20 April 2018.
- ^ a b Born, Charles. "Merle Color in Cocker Spaniels". American Spaniel Club. Retrieved 20 April 2018.
- ^ Born, Charles. "Pomeranian Colors - Any other allowable color". American Pomeranian Club. Retrieved 20 April 2018.
- ^ Registration of dogs of merle colouring 9 January 2020 www.thekennelclub.org.uk accessed 20 March 2021
- ^ Jess Chappell: Dog Coat Colour Genetics: Doppel-Merle www.doggenetics.co.uk
- ^ Sheila, Schmutz. "Schmutz – Merle". Sheila Schmutz. Retrieved 27 October 2011.
- ^ "White Aussies Brochure" (PDF). White Aussies Project. Retrieved 27 October 2011.
- ^ "Double Merle". White Aussies Project. Retrieved 27 October 2011.
- ^ PMID 16407134.
- ^ "UC Davis – Merle genetic testing". UC Davis. Retrieved 20 April 2018.
- ^ ISBN 978-0-7641-0558-6.
- ^ Schmutz, Sheila. "Schmutz – Merle". Sheila Schmutz. Retrieved 27 October 2011.
- ^ "Cryptic Merles". ASHGI. Retrieved 20 April 2018.
- ^ "Dog Coat Colour Genetics". doggenetics.co.uk.
- PMID 30235206.
- PMID 19192156.
- ^ "Merle to merle mating in dogs". The Kennel Club. 18 May 2012. Archived from the original on 1 July 2012. Retrieved 7 September 2012.
- ISBN 978-0-387-76722-2.
- ^ "Eye defects in Australian Shepherds". Retrieved 16 April 2011.
- ^ a b c "George Strain on Merle" (PDF). Merle Poms. Retrieved 27 October 2011.
- ^ "Deaf Dogs Roundtable". Retrieved 16 April 2011.
External links
- Merle dog coat color genetics
- Deafness in Dogs and Cats
- White Aussies Project
- Genetics of merle dogs
- ASCA. "Basic Body Colors of the Australian Shepherd". Archived from the original on 2007-04-08. Retrieved 2007-05-15.: Basic, simple-language explanation of Australian Shepherd merle colorings
- Homozygous "Lethal White" Merles
- Border Wars - Double Merle Articles
- Banning of Merle 'pattern' Chihuahua in Canada
- Catahoula Coat Color Genetics - Introduction and History of Merle
https://www.americanspanielclub.org/about-the-breed/merle-color-in-cocker-spaniels/