THE AGOUTI SERIES

The agouti series consists of:
A^y - sable
a^w - agouti
a^s - saddle pattern
a^t - tan points
a - recessive black

Broadly speaking, the agouti series controls which cells produce eumelanin (black pigment) and, in the case of the agouti gene itself, when.

This pattern of the spread of black hairs is followed by all of the genes in the A series (with the exception of recessive black). There is something inherent in the agouti series which causes this pattern, but as it's not found in most other animals with agouti, no one is entirely sure what it is. Sable can have roughly any pattern shown here, agouti and tan pointed dogs have the last patterns in the animation, and the saddle pattern is anything up to the tan point pattern. Sounds complicated, but it'll become clearer later on.

SABLE

Sable (A^y) is the top dominant in the agouti series, so a dog only needs one sable gene to express it.

There are three types of pattern that can be caused by this gene, but it's not certain what causes each one to appear. It's probable that sable is simply affected by (as yet unidentified) modifiers.

The three patterns are: clear sable, tipped sable and shaded sable.

Clear sables are completely red dogs with just a few black hairs. They can be almost impossible to distinguish from recessive red dogs (see the E series page) unless they have a black mask (E^m), which never appears on recessive reds (because they're unable to produce any black hairs). If there is any black in the coat at all, the dog must be a sable rather than a recessive red.

Tipped sables are red dogs with black hairs, usually on the back, head and tail. It seems that most tipped sables also have black masks (E^m), so it's possible there is a link between the two genes (although not all masked sables have tipping).

Shaded sables are red dogs with brown and black hairs covering the top of the head, ears and back, in a distinctive pattern similar to the pattern seen on dogs with creeping tan (see below). The shading can be very light (just some scattered dark hairs forming a rough pattern), or very dark and distinct. A distinctive feature is the "widow's peak" on the forehead, where the brown forms a point. Shaded sables are known simply as "sables" in breeds like the Shetland Sheepdog and Rough Collie, and "grizzles" in Salukis. It's also likely that "domino" Afghan Hounds are in fact shaded sables.

(first Sheltie photo taken by Kenzie, second Sheltie photo is of Duke, belonging to Alisa. Norwegian Lundehund photo taken by June)

This striking Border Collie cross, Roscoe, has very heavy sabling. His long coat makes it difficult to see precisely which type of sable he is, but the clear red on his legs suggests he is a shaded sable. Alternatively he could have the saddle pattern (see the section below), as those black lines running from the edge of his eyes are often associated with saddles, but his colouring appears too patchy for that.
In addition to his sable pattern, he has a black mask (E^m) and white markings in the irish spotting pattern (as he's "flashy", i.e. has a lot of white, he is probably sⁱs^p).
Roscoe, and his photos, belong to Lindsay at Nordic.

AGOUTI

Agouti is one of the oldest and most widespread mammal colour genes. It can be found on rodents, deer, wild rabbits, and it's even the main colour phase of the wolf. The main reason it's so popular is the camouflage it provides.

Agouti is typified by strands of fur which are banded. This means that as the fur is growing, first the cells produce one type of pigment (usually eumelanin, so black pigment) and then they switch to another type (usually phaeomelanin, so red). The gene that tells the cells to keep changing the pigment they produce is generally classified as a^w.

Now the agouti gene in rabbits and deer produces banded hairs all over the coat, but for some reason the agouti gene in dogs is a little different. It restricts the banded hairs to certain parts of the coat, which are, roughly, the upper parts (back, head, top of legs etc). It's a gene inherited from the wolf, and can be seen on many breeds which are considered to be close to wolves (e.g. Czech Wolfdogs, Saarloos Wolfhonds), as well as some Northern spitz-type breeds (Keeshond, Elkhound).

In its normal form, agouti can be almost identical to shaded sable. The main difference is the banded hairs, but if you can't get close enough to see those, the pattern is also slightly different. Agouti tends to follow the same pattern as traditional tan points rather than creeping tan (see below), although it does appear to vary.

When combined with one of the chinchilla genes (see the C locus page), agouti becomes much more distinctive. Chinchilla dilutes red pigment (phaeomelanin), so the red hairs on an agouti dog become cream or greyish. The result is a wolf grey dog, like the Keeshond or the Elkhound. The Keeshond has partial dilution of phaeomelanin, which leaves cream points, and the Swedish Elkhound below has almost full dilution of phaeomelanin, leaving off-white points. The Wire-haired Dachshund, Keeshond and Elkhound show the different appearances of agouti. All three photos were taken by June.

It's also worth noting that so-called "sable" German Shepherd Dogs are in fact agouti.

This wolf grey Swedish Vallhund is eager to show you how light his underbody is!

SADDLE PATTERN

The saddle pattern gene restricts dark pigment (eumelanin) to the dog's back. The rest of the coat is red.

Sometimes the black saddle can have interspersed red hairs. This occurs in some terrier breeds and is known as grizzle.

Saddles can vary from just a small patch of black on the back to covering the whole of the back, tail, back of the neck and top of the head. Saddle-marked dogs with a lot of black are generally known as creeping tan. Creeping tan is like the traditional tan pattern (see the section below), but the tan covers more of the face, comes further up the legs, and covers a larger area of the front of the chest. It's not known whether this pattern is caused by the saddle gene or the tan point gene, but I think it's more likely to be connected to saddles.

The saddle gene is particularly common in terrier and hound breeds, particularly those originating in the UK. It's probable that the gene mutation causing saddles originally occurred in Europe.

The Yorkshire Terrier above has red (tan) back legs, but these are covered up by the long hair. Its fur is a silvery colour due to the greying gene (G). The faded saddle on the Otterhound is probably also caused by greying. The Norwich Terrier photo was taken by June.

The saddle pattern is also the main colour of the German Shepherd Dog. This beautiful GSD, Shala, is owned by Ratty from the PKC forum. Her muzzle is black because she also has a mask (E^m).

Saddled dogs are usually born black and tan. The black recedes as the dog grows.

Compare this Airedale puppy with the adult on the right. The change is quite dramatic! Both of the photos were taken by Kenzie.

TAN POINTS

The tan point gene (known as "traditional tan points") is almost the bottom recessive in the agouti series (the only one below it is recessive black, which is very rare). This means that, generally, a dog must have two copies of the tan point gene in order to express tan points, so their A locus genotype must be a^ta^t.

The range of markings on a tan pointed dog are very restricted. Red (tan) appears as pips above the eyes, on the sides of the muzzle extending to the cheeks, as pips on the cheeks, on the neck just below the head, as two triangular patches on the front of the chest, on the lower legs (and inside of the legs), and as a patch underneath the tail (and sometimes along the bottom edge of the tail too). The main colour is solid black (or any other eumelanin colour - liver, isabella or blue - depending on the other genes involved). Sometimes black marks are present on the toes. This is called "pencilling".

The Miniature Pinschers below show the black and tan pattern off well. Other well-known breeds with this pattern include the Bernese Mountain Dog (which also has white markings), the Dobermann, Rottweiler, Australian Cattle Dog, Collie and Dachshund.

Sometimes the points on the face can be covered up by a mask, as on this Tibetan Spaniel. The eyebrow pips are still visible, but the sides of the muzzle are covered by black.

RECESSIVE BLACK

Recessive black is a rare, recently discovered gene which is the bottom recessive in the agouti series. See the page on black (K locus) for more information on it (it seemed to fit better there!).

OTHER GENES AFFECTING THE AGOUTI SERIES

All of the genes above - sable, saddle, tan points and agouti - can be affected by numerous other genes which change their appearance, including merle, liver, dilution, chinchilla, greying, and even dalmatian spots.

Here are just a few examples. For more, see the individual locus pages.

This is a clear sable Podengo Portugueso with the dilution gene (dd), which has turned its black pigment to blue. If it had any black tipping, it would also be blue.

This Italian Greyhound also has the dilution gene, this time combined with white in the irish spotting pattern. It's difficult to work out which A series gene this dog has. The tan is too high for tan points, so it's possibly creeping tan instead, or maybe heavily shaded sable. Who knows! Both of those genes are pretty much unknown in the breed, so by all accounts this is a rare dog. The German Pinscher next to it shows the traditional tan pattern, also with dilution to blue.

This is an unusual example of a tan-pointed Miniature Pinscher with the liver and dilution genes. This results in a dusty brown colour called isabella.

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