Labradors are relatively large, with males typically weighing 29-41 kg (65-90 pounds) and females 25–32 kg (55–71 lb). Labs weighing close to or over 100 lbs are considered obese or having a major fault under American Kennel Club standards, although some labs weigh significantly more. The majority of the characteristics of this breed, with the exception of colour, are the result of breeding to produce a working retriever.
As with some other breeds, the Conformation (typically "English", "show" or "bench") and the Field (typically "American" or "working") lines differ, although both lines are bred in both countries. In general, however, Conformation Labs tend to be bred as medium-sized dogs, shorter and stockier with fuller faces and a slightly calmer nature than their Field counterparts, which are often bred as taller, lighter-framed dogs, with slightly less broad faces and a slightly longer nose; however Field labs should still be proportional and fit within AKC standards. With field labs, excessively long noses, thin heads, long legs and lanky frames are not considered standard. These two types are informal and not codified or standardised; no distinction is made by the AKC or other kennel clubs, but the two types come from different breeding lines. Australian stock also exists; though not seen in the west, they are common in Asia.
The breed tends to shed hair twice annually, or regularly throughout the year in temperate climates. Some labs shed a lot; however, individual labs vary. Labrador hair is usually fairly short and straight, and the tail quite broad and strong. The otter-like tail and webbed toes of the Labrador Retriever make them excellent swimmers. Their interwoven coat is also relatively waterproof, providing more assistance for swimming.
Official breed standards
There is a great deal of variety among Labs. 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 AKC standard. Significant differences between US and UK standards are noted.
Size: Labs are a medium-large but compact breed. They should have an appearance of proportionality. They should be as long from the withers to the base of the tail as they are from the floor to the withers. Males should stand 22.5–24.5 inches (57–62 cm) tall at the withers and weigh 65–80 lb (29–36 kg). Females should stand 21.5–23.5 inches (55–60 cm) and weigh 55–70 lb (25–32 kg). By comparison under UK Kennel Club standards, height should be 22–22.5 inches (56–57 cm) for males, and 21.5–22 inches (55–56 cm) for females.
Coat: The Lab's coat should be short and dense, but not wiry. The coat is described as 'water-resistant' or more accurately 'water-repellent' so that the dog does not get cold when taking to water in the winter. That means that the dog naturally has a slightly dry, oily coat. Acceptable colours are black, yellow (ranging fom ivory or creme to fox red), and chocolate.
Head: The head should be broad with a pronounced stop and slightly pronounced brow. 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 are 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 be strong and muscular with a level top line.
The tail and coat are designated "distinctive [or distinguishing] features" of the Labrador by both the Kennel Club and AKC. The AKC adds that "true Labrador Retriever temperament is as much a hallmark of the breed as the 'otter' tail."
As well, Labradors should not have droopy eyes (like a Basset Hound). The skin should be relatively tight, and you should not be able to see the pinks on the inside of their lids.
Labrador Retrievers are registered in three colors: black (a solid black color), yellow (anything from light cream to "fox-red"), chocolate (medium to dark brown).
Puppies of all colors can potentially occur in the same litter. Color is determined primarily by two genes. The first gene (the B locus) determines the density of the coat's pigment granules: dense granules result in a black coat, sparse ones give a chocolate coat. The second (E) locus determines whether the pigment is produced at all. A dog with the recessive e allele will produce little pigment and will be yellow regardless of its genotype at the B locus. Variations in numerous other genes control the subtler details of the coat's coloration, which in yellow Labs varies from white to light gold to a fox red. Chocolate and black Labs' noses will match the coat color.
Nose and skin pigmentation
Because Labrador coloration is controlled by multiple genes, it is possible for recessive genes to emerge some generations later and also there can sometimes be unexpected pigmentation effects to different parts of the body. Pigmentation effects appear in regard to yellow Labradors, and sometimes chocolate, and hence the majority of this section covers pigmentation within the yellow Labrador. The most common places where pigmentation is visible are the nose, lips, gums, feet, tail, and the rims of the eyes, which may be black, brown, light yellow-brown ("liver", caused by having two genes for chocolate), or several other colors. A Labrador can carry genes for a different color, for example a black Labrador can carry recessive chocolate and yellow genes, and a yellow Labrador can carry recessive genes for the other two colors. DNA testing can reveal some aspects of these. Less common pigmentations (other than pink) are a fault, not a disqualification, and hence such dogs are still permitted to be shown. The intensity of black pigment on yellow Labs is controlled by a separate gene independent of the fur colouring. Yellow Labradors usually have black noses, which may gradually turn pink with age (called "snow nose" or "winter nose"). This is due to a reduction in the enzyme tyrosinase which indirectly controls the production of melanin, a dark colouring. Tyrosinase is temperature dependent—hence light colouration can be seasonal, due to cold weather—and is less produced with increasing age two years old onwards. As a result, the nose colour of most yellow Labs becomes a somewhat pink shade as they grow older.
A colouration known as "Dudley" is also possible. Dudleys are variously defined as yellow Labs which have no pigmented (pink) noses (LRC), yellow with liver/chocolate pigmentation (AKC), or "flesh colored" in addition to having the same color around the rims of the eye, rather than having black or dark brown pigmentation. A yellow Labrador with brown or chocolate pigmentation, for example, a brown or chocolate nose, is not necessarily a Dudley, though according to the AKC's current standard it would be if it has chocolate rims around the eyes (or more accurately of the genotype eebb). Breed standards for Labradors considers a true Dudley to be a disqualifying feature in a conformation show Lab, such as one with a thoroughly pink nose or one lacking in any pigment along with flesh colored rims around the eyes. True Dudleys are extremely rare.
Breeding in order to correct pigmentation often lacks dependability. Because color is determined by many genes, some of which are recessive, crossbreeding a pigmentation non-standard yellow Labrador to a black Labrador may not correct the matter or prevent future generations carrying the same recessive genes. For similar reasons, crossbreeding chocolate to yellow labs is also often avoided.
Show and field lines
There are significant differences between field and trial-bred (sometimes referred to as "American") and show-bred (or "English") lines of Labradors, arising as a result of specialised breeding. Dogs bred for hunting and field-trial work are selected first for working ability, where dogs bred to compete in conformation shows are selected for their conformation to the standards and characteristics sought by judges in the show ring.
While individual dogs may vary, in general show-bred Labradors are heavier built, slightly shorter-bodied, and have a thicker coat and tail. Field Labradors are generally longer legged, lighter, and more lithe in build. In the head, show Labradors tend to have broader heads, better defined stops, and more powerful necks, while field Labradors have lighter and slightly narrower heads with longer muzzles. Field-bred Labradors are commonly higher energy and more high-strung compared to the Labrador bred for conformation showing, and as a consequence may be more suited to working relationships than being a "family pet". Some breeders, especially those specialising in the field type, feel that breed shows do not adequately recognise their type of dog, leading to occasional debate regarding officially splitting the breed into subtypes.
In the United States, the AKC and the Labrador's breed club have set the breed standard to accommodate the field-bred Labrador somewhat. For instance, the AKC withers-height standards allow conformation dogs to be slightly taller than the equivalent British standard. However, dual champions, or dogs that excel in both the field and the show ring, are becoming more unusual.