Point coloration: Difference between revisions - Wikipedia

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~~[[Image:Neighbours Siamese.jpg|thumb|A cat with seal (black) point coloration.]]~~

[[Image:Neighbours Siamese.jpg|thumb|A cat with black point coloration]]

'''Point coloration''' is [[Coat (animal)|animal coat]] coloration with a pale body and relatively darker extremities, i.e. the face, ears, feet, tail, and (in males) [[scrotum]]. It is most recognized as the coloration of [[Siamese (cat)|Siamese]] and related breeds of [[cat]], but can be found in [[dog]]s, [[rabbit]]s, [[fancy rat|rats]], [[sheep]], [[guinea pigs]] and [[horse]]s as well.

'''Points''' are specific areas of an [[animal coat]] that are colored differently from the main body colorations. Typical point coloration is represented by a pale body color and relatively darker extremities, such as face, ears, feet, tail, and [[scrotum]].{{r|Steeh}} It is most recognizable in the coloration of [[Siamese (cat)|Siamese cats]], but colored points can be found in many mammal species and some points are lighter than the main body color.

== Temperature-dependent colorpoint ==

~~==In cats==~~

~~{{redirect|Lynx point|the Intel Chipset|Lynx Point}}~~

In many species, colorpoint patterns come from a genetic mechanism causing pigment to be produced only in cooler areas of the body, called [[acromelanism]]. This can be seen in [[cat]]s, [[dog]]s (rare),{{r|Brancalion2021|p=22}} [[fancy rat]]s, [[guinea pig]]s, and [[rabbit]]s.

~~[[File:Siamese Cat with her Kitties.jpg|thumb|New-born kittens suckling milk from their seal point mother cat. Colourpoint kittens are born solid-white.]]~~

Point coloration in cats originated in the [[Siamese cat|Siamese]] and closely related Asian breeds, and is found in many Western-developed modern breeds. It is a form of partial [[albinism]] resulting from a [[mutation]] that affects [[tyrosinase]], an enzyme involved with [[melanin]] production. The mutated enzyme is [[thermolabile]]; it fails to work at normal body temperatures, but becomes active in cooler areas of the skin.<ref>{{cite journal

~~| pmid = 16573534~~

~~| pmc = 1464423~~

|display-authors=etal}}</ref> As a result, dark pigment is limited to the coldest areas of the body, that is, the extremities. Pointed [[kitten]]s are born white, since the womb is uniformly warm. As the kitten ages, the cooler areas darken while warmer areas remain cream to white in color. Points are not limited to solid colors or dark colors. It is possible to have a red (orange color) or fawn (pale warm gray) point. It is also possible to have a [[Tortoiseshell cat|tortoiseshell]] or [[tabby]] point. A cat (of any breed) with this coloration is often called a ''colorpoint cat'' to distinguish it from others.

As the expression of the gene responsible for the pointed pattern is regulated by temperature, pointed cats who live in cooler environments often show increased darkening of their fur relative to cats who live in warmer climates, sometimes even developing large dark areas along their sides.

File:Ghislaine 6028.jpg|Cat

File:Rat siamese.JPG|Fancy rat

Because of the pigment restriction caused by the temperature sensitive tyrosinase, pointed cat's eyes are always shades of blue because the blue layer in the eye common to all cats is not covered by another color. The back of the eye also lacks pigment, giving colorpoint cats' pupils an eerie red and silver reflection in the dark, unlike a normally pigmented cat's shining silver-green or -blue.

File:Himalayan-Guinea pig.jpg|Guinea pig

File:Króliki kalifornijskie 666.jpg|Rabbit

The [[Cat coat genetics|point gene]] allele is at the C [[Locus (genetics)|locus]], where pure [[albinism]] is also carried, and is written as ''cs''. Point is recessive, so two copies of ''cs'', one from each parent, are needed for points to be expressed. Also carried on the C locus is the gene for the ''sepia'' pattern, which allele is represented by ''cb''. This is the darkest of all of the pigment restricting patterns—pigment is only paled at the warmest point in the body: the abdomen. Sepia cats have amber-yellow to green eyes. When a cat carries the genes ''cs'' and ''cb'', the intermediate ''mink'' pattern is formed, in which the pigment distribution is between sepia and point. The eye color of mink cats is on the blue-green spectrum ([[Aquamarine (color)|aquamarine]]).

~~<gallery class="center" caption="Comparison of different black (seal, sable) colourpoint cats">~~

~~File:Siamese cat Vaillante.JPG|Black point [[Siamese cat|Siamese]]~~

~~File:Brown-mink.JPG|Black mink [[Tonkinese cat|Tonkinese]]~~

~~File:Geisha One Year Old (5640618397).jpg|Black sepia [[Burmese cat|Burmese]]~~

~~File:Starglitters Snowflake BEN n 24 33.JPG|Black [[Rosette (zoology)|rosetted]] [[Tabby cat|tabby]] point (lynx) [[Bengal cat|Snow Bengal]]~~

~~File:Tortie-point.jpg|Black [[Tortoiseshell cat|tortoiseshell]] point cat~~

</gallery>

== Dogs ==

~~{{anchor|Lynx point|lynx point|lynx point (coloration)}}~~

[[File:Black & Tan kelpie 2.png|Dog with tan points|thumb|upright]]

The ''lynx point'' pattern is formed by mating a colorpoint cat with a [[tabby cat]] (or breeding cats that already possess the lynx point pattern). It is characterized by a mixture of the darkening (reduced) of point coloration with distinct tabby striping on the head, tail, and legs, and an otherwise uniform and comparatively pale body. It is an accepted pattern in some cat registries, but not others, for particular breeds (mostly Siamese-related).<ref>Which registries accept lynx-point coloration or other point colorations changes fairly frequently and can be checked with registries’ awards searches, e.g. [http://www.tica.org/search?searchword=lynx%20point&ordering=newest&searchphrase=all&limit=20 search for "lynx point" at the TICA website].</ref>

Colored points in dogs are lighter than the body coat, and usually tan. Tan points include small patches above the eyes and on the cheeks, the sides of the muzzle, front of neck and chest, lower legs and insides of legs, and under the tail.{{r|Dreger|Chappell}}

== Horses ==

Point coloration is inherent to the Siamese breed and some other closely related breeds but with most other breeds the colorpoints (including lynx) were brought into some breed lines long after their establishment, but there are exceptions. For example, lynx point was a feature of some of the [[foundation stock]] of the [[Siberian cat|Siberian]], now called the [[Neva Masquerade]].<ref>{{cite web |last=TICA |title=Siberian Introduction |url=https://tica.org/Breed_Introductions/Siberian_Breed_for_Website.pdf}}</ref>

~~===Cat breeds===~~

{{multiple image|perrow = 2 |total_width=350

~~{{div col|colwidth=20em}}~~

|image1 = Nepal, franches-montagnes.jpg

* [[Balinese cat|Balinese]]

|image2 = Dole eating grass.jpg

* [[Birman cat|Birman]]

|image3 = Red roan Quarter Horse.jpg

* [[British Shorthair]]

|image4 = Walking Red Dun.jpg

* [[Burmese cat|Burmese]]

* [[Colorpoint Shorthair]]

}}

* [[Highlander cat|Highlander]]

* [[Himalayan cat|Himalayan]]

* [[Javanese cat|Javanese]]

* [[Napoleon cat|Napoleon]]

* [[Neva Masquerade]]

* [[Peterbald]]

* [[Ragamuffin (cat)|Ragamuffin]]

* [[Ragdoll cat|Ragdoll]]

* [[Siamese cat|Siamese]]

* [[Bengal cat|Snow Bengal]]

* [[Snowshoe cat|Snowshoe]]

* [[Sphynx]]

* [[Thai cat|Thai]]

* [[Tonkinese cat|Tonkinese]]

~~{{div col end}}~~

When referring to horse colors, the ''points'' are the mane, tail, lower legs, and ear rims. Certain combinations of point color and body color determine most horse color names.{{r|sponen2009|p=7}} For example, a [[Bay (horse)|bay horse]] has a reddish-brown body color with black points,{{r|sponen2009|p=17}} and a [[Buckskin (horse)|buckskin]] is a yellowish horse with black points.{{r|sponen2009|p=42}} Some horse colorations have nonblack points (cream, red or brown), such as the [[Dun gene|red dun]] which has red to brown points.{{r|sponen2009|p=43}}

~~==In dogs==~~

~~{{Expand section|date=March 2021}}~~

Tan points on dogs includes point coloration on a black or dark base coat with tan cheek spots, eyebrows, feet, forelegs and tail vent.<ref>{{cite web |title=GLOSSARY OF TERMS Used in Relation to Dog Coat Colours and Patterns |url=http://www.lowchensaustralia.com/articles/dogcolours.htm |website=www.lowchensaustralia.com |publisher=Chinaroad Lowchens of Australia |accessdate=11 December 2018}}</ref> Typical tan point breeds include [[Dobermann]] and [[Rottweiler]].<ref>{{cite web |title=Dog Coat Colour Genetics |url=http://www.doggenetics.co.uk/tan.html#tan |website=www.doggenetics.co.uk |accessdate=11 December 2018}}</ref>

In a color with points (black or nonblack) the legs are dark and the color goes all the way down to the hoof, whereas in a horse color without points the color just above the hoof is lighter than its body color.{{r|sponen2009|p=7}} [[Roan (horse)|Roan horses]] have white hairs interspersed throughout their body color, but the points are unaffected and remain black,{{r|sponen2009|p=210}} however a horse with [[horse markings#Leg markings|high white leg markings]] might have their points obscured.{{r|sponen2009|p=8}}

Rarely, dogs may also have a point coloration similar to that of Siamese cats.<ref>{{cite journal|doi=10.1016/j.gene.2020.145212|title=Identification of a candidate genetic variant for the Himalayan color pattern in dogs|year=2021 |last1=Bychkova |first1=Elina |last2=Viktorovskaya |first2=Olga |last3=Filippova |first3=Elizaveta |last4=Eliseeva |first4=Zhanna |last5=Barabanova |first5=Larisa |last6=Sotskaya |first6=Maria |last7=Markov |first7=Anton |journal=Gene |volume=769 |page=145212 |pmid=33039541 |s2cid=222302410 }}</ref>

==In ~~horses~~Donkeys ==

~~{{main|Bay (horse)|Agouti coloration genetics}}~~

~~[[File:Trotting Belgian draft horse.jpg|thumb|A bay horse, showing black points]]~~

In horses, point coloration is most often produced by the action of the [[Agouti signalling peptide|agouti]] gene. It acts on the [[Melanocortin 1 receptor|extension gene]], when present, to suppress black color to all but the extremities of the horse; the legs, mane, tail and tips of the ears. If the extension gene is not present, the effect of agouti is not visible, as there is no black color present to suppress. Points are most typically seen on a [[bay (horse)|bay]]-colored horse, which has a black mane, tail, legs, and ear tips while the body and head will show the underlying [[chestnut (coat)|chestnut]] or "red" base color.

[[File:Donkey - Bearizona Wildlife Park (7177920492).jpg|thumb|upright|A donkey with typical light points]]

Other genes [[horse markings|white markings]] may affect a horse's coat color in addition to agouti, and if present, can further alter or suppress black hair color and may mask any point coloration. In particular, [[gray (horse)|Gray]] horses are born dark and lighten with age; if born bay, they will eventually lose point coloration as the body hair silvers with age, though often the points are the slowest areas of the body to go gray.

In [[donkey]]s, the term "points" refers to the muzzle, rings around the eyes, belly, and upper inner legs, which are usually light in color. The mane, tail, and ear rims are referred to as "trim" and roughly correspond to the "points" of horses. Most donkeys have light points. The coat colors without light points may be called "no light points", "dark points", or "black points". Dark points are caused by a recessive allele of agouti found in Normand and Miniature donkeys. The light areas may vary in extent, with some donkeys having a dark nose but with light areas on the insides of the legs.{{r|sponen2009|pp=133-5}}

== Sheep ==

~~Point coloration may also be visible on horses with other [[dilution gene]]s that act upon a bay base coat. These include:~~

* The [[cream gene]], an [[incomplete dominant]], that when [[heterozygous]] produces [[Buckskin (horse)|Buckskin]]. When homozygous, even point coloration is mostly suppressed, the color is called [[perlino]], and some individuals may have slightly redder hair at the traditional point coloration locations.

* The [[Champagne gene]], which on a bay base produces Amber Champagne.

[[File:Ram of the Clun Forest breed.jpg|thumb|upright|A sheep showing point coloration of its face, ears, and legs]]

A dilution gene that produces what looks like point coloration, but from a completely different genetic mechanism is the [[dominance relationship|dominant]] [[Dun gene]], which dilutes the color of the body coat but not the points, including [[primitive markings]]—a dorsal stripe down the back and, less often, horizontal striping on the upper legs. On a bay base coat the dun gene leaves black points, producing a Bay Dun or "Zebra" Dun. But the gene also leaves the points dark when it appears with other base colors. These include the “blue dun” or [[grullo]], which has a black base coat, and the red dun, which has a chestnut base coat.

Some breeds of sheep exhibit point coloration with a white fleece and colored head and legs, usually black.{{r|suffolks}} Sheep breeds with black points include: [[Clun Forest sheep|Clun Forest]], [[Dorset Down]], [[Hampshire Down]], [[Norfolk Horn]], [[Oxford Down]], [[Shropshire sheep|Shropshire]], [[Suffolk sheep|Suffolk]], and [[Valais Blacknose]]. Instead of black, [[American Tunis]] sheep have a red face, and [[Wensleydale sheep]] have a blue-grey face.

== Cattle ==

Similarly, darker coloration at the points is also preserved in horses with the [[roan (horse)|roan gene]], a patterning gene, producing a body coat of mingled white and dark hairs, but leaving the points the darker base color in all horses, not just those carrying agouti.

[[File:British White calf trio.jpg|thumb|upright|British White calves]]

Most other genes that produce spotting patterns or [[white markings]] allow point coloration produced by agouti to show except where masked by white depigmentation. There are not always separate names for a pattern over a bay base coat, but one exception is the [[Pinto horse|Bay pinto]], sometimes called [[Tricolour (horse)|”tricoloured”]].

In cattle, extreme [[color-sided]]ness creates a colorpoint pattern with a white body and darker ears, nose, and feet. Breeds displaying this pattern include the [[White Park cattle|White Park]], [[British White]] and some [[Irish Moiled]].{{r|porter2016|p=127}}

== See Also ==

~~<gallery>~~

* [[Cat coat genetics]]

~~File:800 Örn frá Arnarstöðum.jpg|White markings may partially or completely mask point coloration in horses~~

* [[Dog coat genetics]]

~~File:Showmanship at Scottsdale 09.jpg|The dun gene leaves the points darker on all base coat colors, not just when agouti is present~~

~~File:Red roan Quarter Horse.jpg|The roan pattern allows point coloration to show on the head as well as traditional point locations~~

~~</gallery>~~

==References==

~~{{-}}~~

{{Reflist|refs=

<ref name="Brancalion2021">{{cite journal |last1=Brancalion |first1=L |title=Canine coat pigmentation genetics: a review |journal=Animal Genetics |date=2022 |volume=53 |issue=1 |pages=3–34 |doi=10.1111/age.13154 |url=https://onlinelibrary.wiley.com/doi/10.1111/age.13154 |access-date=21 August 2024}}</ref>

~~== In rabbits and rodents ==~~

~~[[Image:Króliki kalifornijskie 666.jpg|thumb|right|Rabbits of the Californian breed showing coats with point coloration]]~~

All pointed white rabbits of true breeding have red eyes.<ref>{{Citation|title=Himalayan rabbit|date=2020-01-14|url=https://en.wikipedia.org/w/index.php?title=Himalayan_rabbit&oldid=935728240|work=Wikipedia|language=en|access-date=2020-09-02}}</ref> The pointed white rabbit is created with the ch gene.<ref>{{Cite web|title=Rabbit Color Genetics: Self Chinchilla Explained – Rabbit Smarties : Creative Resources for Rabbit Keepers|date=19 July 2011 |url=https://rabbitsmarties.com/2011/07/rabbit-color-genetics-chinchilla-explained/|access-date=2020-09-02|language=en-US}}</ref> Its presentation is typified in the [[Himalayan rabbit]] breed (the first rabbit breed with a pointed white coat) and in the [[Californian rabbit|Californian]] breed.

<ref name="Chappell">{{Cite web |url=http://www.doggenetics.co.uk/tan.html#tan |title=The Agouti Series : Tan Points |website=Dog Coat Color Genetics |first=Jess |last=Chappell}}</ref>

~~===Rabbit coat colors===~~

Some rabbits that appear to be pointed white lack the red eyes, which indicates they are of different breeding. The following such coat colors are examples of those created, not with the ch gene, but with the cchl, cchd, or cchm gene in conjunction with the e gene:{{citation needed|date=February 2018}}

~~{{div col|colwidth=8em}}~~

* Blue point

* Chocolate point

* Lilac point

* Pearl

* Sable point

* Sallander

* Seal point

* Siamese

~~{{div col end}}~~

<ref name="Dreger">{{cite journal|last1=Dreger|first1=Dayna L.|last2=Schmutz|first2=Sheila M.|year=2011|title=A SINE Insertion Causes the Black-and-Tan and Saddle Tan Phenotypes in Domestic Dogs|journal=Journal of Heredity|volume=102|issue=Suppl 1|pages=S11–S18|doi=10.1093/jhered/esr042|pmid=21846741|doi-access=free}}</ref>

No pointed white rabbit can produce orange pigment; therefore, the points are always either black, blue, chocolate, or lilac.{{citation needed|date=February 2018}} The resulting point coloration is sometimes in conjunction with a coat pattern, such as: white agouti, marten, broken, Vienna, or harlequin. (Such coats may not be recognized for showing.)

<ref name="porter2016">{{Cite book |first1=Valerie |last1=Porter |first2=Lawrence |last2=Alderson |first3=Stephen J.G. |last3=Hall |first4=D. Phillip |last4=Sponenberg |year=2016 |url=https://books.google.com/books?id=2UEJDAAAQBAJ |title=Mason's World Encyclopedia of Livestock Breeds and Breeding |edition=Sixth |publisher=[[CAB International|CABI]] |isbn=9781780647944}} </ref>

~~===Rabbit breeds===~~

[[List of rabbit breeds|Breeds of rabbit]] that include varieties with point coloration include:<ref name="ARBA Standard">{{cite book|title=Standard of Perfection 2016-2020|date=2015|publisher=American Rabbit Breeders Association|asin=B018GVBJK4}}</ref><ref name="BRC Standard">{{cite web|title=Breed Standards 2016-2020|url=http://www.thebrc.org/Mono%20Breed%20Standards%20Book%20APRIL%202017%20small.pdf|website=British Rabbit Council|access-date=11 February 2018|archive-url=https://web.archive.org/web/20180121125834/http://www.thebrc.org/Mono%20Breed%20Standards%20Book%20APRIL%202017%20small.pdf|archive-date=21 January 2018|url-status=dead}}</ref>

<ref name="sponen2009">{{Cite book |title=Equine Color Genetics |first=D. Phillip |last=Sponenberg |edition=3rd |year=2009 |publisher=Blackwell Pub. |isbn= |ol=22501687M}}</ref>

~~{{div col|colwidth=20em}}~~

* [[Altex rabbit|Altex]]

* [[American Fuzzy Lop]]

* [[Angora rabbit|English Angora]]

* [[Angora rabbit|French Angora]]

* [[Californian rabbit|Californian]]

* [[Cashmere Lop]]

* [[Himalayan rabbit|Himalayan]]

* [[Holland Lop]]

* [[Jersey Wooly]]

* [[Lionhead rabbit|Lionhead]]

* [[Mini Lop]]

* [[Mini Rex]]

* [[Mini Satin (rabbit)|Mini Satin]]<sup>(in development)</sup>

* [[Netherland Dwarf]]

* [[Pointed Beveren (rabbit)|Pointed Beveren]]

* [[Rex rabbit|Rex]]

* [[Satin (rabbit)|Satin]]

* [[Angora rabbit|Satin Angora]]

~~{{div col end}}~~

<ref name="Steeh">{{Cite book |title=Cat breeds |first=Judith A. |last=Steeh |year=1984 |publisher=Gallery Books |isbn=0831712023 |ol=24961512M |page=10 |quote=The colorpoint pattern consists of a basic body color and a contrasting point color. The points appear on the cooler extremities of the cat, and have sometimes been called 'temperature points.' The points, which must be well-defined, of a contrasting color, and of the same color density, are the mask, ears, feet, tail, and sex organs. There should not be any ticking or white hairs in the points. The mask should cover the entire face, including the whisker pads, and be connected to the ears by 'tracings' ; it should not, however, extend over the top of the head.}}</ref>

~~===In fancy (domestic) rats===~~

~~The C - Albino locus gene causes dilution of yellow and black coloration, causing Himalayan or Siamese markings depending on the allele is affected.~~

<ref name="suffolks">{{cite web|url=https://suffolks.org/pdf/2022/Suffolk_Breed_Standards-updated.pdf |publisher=United Suffolk Sheep Association|access-date=Sep 28, 2024|title=Suffolk Breed Standards}}</ref>

~~Point colors in rats include:~~

}}

* Sepia

* Seal Point

* Blue Point<ref>{{Cite web|url=https://www.afrma.org/ratgenpart1.htm|title = AFRMA - Rat Genetics, part 1}}</ref>

~~=== In guinea pigs ===~~

~~There is only one type of guinea pig with a pointed coat. It is called the [[Himalayan guinea pig|Himalayan]], has either Black (a very dark brown) or Chocolate, tipped on the Ears, Nose, and Feet.~~

~~==In sheep==~~

~~[[File:Hampshire down.jpg|thumb|Hampshire sheep showing point coloration of their faces, ears, and legs]]~~

~~Some breeds of sheep exhibit point coloration.~~

~~===Sheep breeds===~~

~~{{div col|colwidth=22em}}~~

* [[Clun Forest (sheep)|Clun Forest]]

* [[Dorset Down]]

* [[Hampshire sheep|Hampshire]]

* [[Norfolk Horn]]

* [[Oxford sheep|Oxford]]

* [[Shropshire (sheep)|Shropshire]]

* [[Suffolk (sheep)|Suffolk]]

* [[Tunis (sheep)|Tunis]]

* [[Valais Blacknose (sheep)|Valais Blacknose]]

* [[Wensleydale (sheep)|Wensleydale]]

~~{{div col end}}~~

~~==References==~~

~~{{reflist}}~~

[[Category:Cats]]

[[Category:Animal coat colors]]

[[Category:Horse coat colors]]

[[Category:Cat coat types]]