Editing Labrador Retriever (section)

== Characteristics ==
[[File:Afra 013.jpg|thumb|The head is broad with a pronounced stop.]]
[[File:Labrador retriever bulaj1.jpg|thumb|Black]]
[[File:Labrador Retriever chocolate Hershey sit (cropped).jpg|thumb|Chocolate]]

There is a great deal of variety among Labradors. The following characteristics are typical of the [[conformation show]] bred (bench-bred) lines of this breed in the United States and are based on the American Kennel Club standard.<ref name="akc">{{cite web
  | title =Labrador Retriever Breed Standard
  | publisher =[[American Kennel Club]]
  | date =31 March 1994
| url =http://www.akc.org/breeds/labrador_retriever/index.cfm
  | access-date = 13 September 2007}}</ref> Significant differences between UK and US standards are noted.
* '''Size''': Labradors are a medium-large breed. They should be as long from the [[withers]] to the base of the tail as they are from the floor to the withers. The AKC standard includes an ideal weight for dogs of {{convert|55|-|80|lb|kg|abbr=on|disp=flip|0}} and for bitches as {{convert|55|-|70|lb|kg|abbr=on|disp=flip|0}}.<ref name="akc" /> The guidelines for height vary between the AKC, which gives {{convert|21.5|to|24.5|in|cm|disp=flip|0}} for dogs and {{convert|21.5|to|23.5|in|cm|disp=flip|0}} for bitches,<ref name="akc" /> The Kennel Club which advises that dogs should be {{convert|56|to|57|cm|in|round=0.5}} with bitches between {{convert|55|and|56|cm|in|round=0.5}},<ref name="kc">[http://www.thekennelclub.org.uk/item/109 Retriever (Labrador) Breed Standard] {{webarchive|url=https://web.archive.org/web/20111031032613/http://www.thekennelclub.org.uk/item/109 |date=31 October 2011 }}. The Kennel Club.</ref> and the FCI which quotes a range of {{convert|56|to|57|cm|in|round=0.5}} for dogs with bitches ideal at {{convert|54|to|56|cm|in|round=0.5}}.<ref name=fci>[http://www.fci.be/Nomenclature/Standards/122g08-en.pdf Labrador Retriever]. Fédération Cynologique Internationale. Accessed May 2020.</ref>
* '''Coat''': The Labrador Retriever's coat should be short and dense, but not wiry. The coat is water-resistant, so the dog does not get cold when taking to the water in the winter. That means that the dog naturally has a slightly dry, oily coat. Acceptable colours are black, yellow, and chocolate.<ref name="akc.org">[http://www.akc.org/breeds/labrador_retriever/index.cfm "Get to Know the Labrador Retriever"], 'The American Kennel Club', Retrieved 29 May 2014</ref>
* '''Head''': The head should be broad with slightly pronounced eyebrows. The eyes should be kind and expressive. Appropriate eye colours are brown and hazel. The lining around the eyes should be black. The ears should hang close to the head and be set slightly above the eyes.
* '''Jaws''': The jaws should be strong and powerful. The muzzle should be of medium length and should not be too tapered. The jaws should hang slightly and curve gracefully back.
* '''Body''': The body should have a powerful and muscular build.

The tail and coat are designated "distinctive [or distinguishing] features" of the Labrador by both the Kennel Club and AKC.<ref name="akc"/><ref name="kc" /> The AKC adds that the "true Labrador Retriever temperament is as much a hallmark of the breed as the 'otter' tail."<ref name="akc" />

=== Colour ===
{{Main|Labrador Retriever coat colour genetics}}
[[File:3labradorcols.jpg|thumb|alt=three Labrador retrievers: Yellow, black, and chocolate|The three colour varieties, from front to back: Yellow, black, and chocolate]]

Labradors are registered in three colours: Solid ''black'', ''yellow'' (anything from creamy white to fox-red), and ''chocolate'' (medium to dark brown; originally called "liver").<ref>
{{cite web
 |title=Breed colours
 |website=thekennelclub.org.uk
 |publisher=[[The Kennel Club]]
 |url=http://www.thekennelclub.org.uk/services/public/breed/colours.aspx?id=2048
 |access-date=10 January 2015 |url-status=dead
 |archive-url=https://web.archive.org/web/20150110200738/http://www.thekennelclub.org.uk/services/public/breed/colours.aspx?id=2048
 |archive-date=10 January 2015
}}
</ref>

Puppies of all colours can occur in the same [[Litter (animal)|litter]]. Coat colour is determined primarily by three genes, called [[Melanocortin 1 receptor|''MC1R'']], [[Agouti coloration genetics|''Agouti'']], and ''CBD103''. If a dog carries [[Wild type|wild type alleles]] at all three loci, the dog will have a yellow coat. If a dog has a loss-of-function mutation at MC1R, it will also have a yellow coat, regardless of the genotypes at the other two loci. Dogs carrying wild-type alleles for MC1R and Agouti, together with the black allele of CBD103, will have a black coat.<ref name=Candille-Kaelin-etal-2007>
{{cite journal
 |last1=Candille   |first1=Sophie I.    |last2=Kaelin  |first2=Christopher B.
 |last3=Cattanach  |first3=Bruce M.     |last4=Yu      |first4=Bin
 |last5=Thompson   |first5=Darren A.    |last6=Nix     |first6=Matthew A.
 |last7=Kerns      |first7=Julie A.     |last8=Schmutz |first8=Sheila M.
 |last9=Millhauser |first9=Glenn L.     |last10=Barsh  |first10=Gregory S.
 |year=2007
 |title=A β-defensin mutation causes black coat colour in domestic dogs
 |journal=[[Science (journal)|Science]]
 |volume=318  |issue=5855  |pages=1418–1423
 |pmid=17947548  |doi=10.1126/science.1147880
 |bibcode=2007Sci...318.1418C  |pmc=2906624
 | issn=0036-8075}}
</ref>{{efn|
"Production of yellow versus black pigment in dogs is controlled by three genes: MC1R, Agouti, and CBD103. Dogs carrying wild-type alleles for all three genes have a yellow coat resulting from Agouti antagonism of MC1R signaling in melanocytes (yellow Great Dane, top). Dogs carrying a loss-of-function mutation at MC1R have a yellow coat, regardless of their genotype at Agouti or CBD103 (yellow Labrador retriever, middle). Dogs carrying wild-type alleles for MC1R and Agouti, together with the dominant black allele of CBD103 (KB) have a black coat resulting from the interaction between a β-defensin and MC1R (black Curly Coated Retriever,{{nobr| bottom)." — Candille, Kaelin, ''et al.'' (2007)<ref name=Candille-Kaelin-etal-2007/>}}
}}

According to a 2011 study, 13 out of 245&nbsp;Labradors studied were [[heterozygous]] for the M264V mutation responsible for the [[melanistic mask]], and one was [[homozygous]]. Within this breed, the trait cannot be determined simply by appearance.<ref>
{{cite journal
 |last1=Conant  |first1=E.K.
 |last2=Juras   |first2=R.
 |last3=Cothran |first3=E.G.
 |year=2011
 |title=Incidence of the mask phenotype M264V mutation in Labrador retrievers
 |journal=Research in Veterinary Science
 |volume=91  |issue=3  |pages=e98–e99
 |doi=10.1016/j.rvsc.2011.02.002  |pmid=21353269
}}
</ref>
[[File:ChocolateLabPup.jpg|thumb|The most common places where pigmentation is visible are the nose, lips, gums, and the rims of the eyes.]]

=== Show and field lines ===
[[File:American and English Labrador heads.jpg|thumb|Head and [[Snout|muzzle]] appearance: field (left), and show (right), showing the shorter muzzle length, more solid appearance of the head, and "pronounced" stop of the latter]]
As a result of specialised breeding, there are significant differences between field and trial-bred and show-bred lines of Labradors. In the United States, the former are sometimes mistakenly referred to as "American" and the latter as "English." In fact, both field and show types are bred in both countries and all Labrador Retrievers are descended from British lines.<ref>{{cite web|last=American Kennel Club|first=The Labrador Retriever Club, Inc.|title=American vs. English|url=http://www.thelabradorclub.com/subpages/show_contents.php?page=English+vs.+American|access-date=2 September 2012|archive-url=https://web.archive.org/web/20170705101113/http://www.thelabradorclub.com/subpages/show_contents.php?page=English+vs.+American|archive-date=5 July 2017|url-status=dead}}</ref>