Tortoiseshell cat

{{Short description|Two-coloured coat colouration in cats}} {{Use British English|date=March 2026}} {{Use dmy dates|date=October 2023}}

[[File:Mudball_(2017_photo;_cropped_2022).jpg|thumb|A black tortoiseshell moggy cat]] '''Tortoiseshell''' is a coat colouration in domestic cats named for its similarity to tortoiseshell pattern. Tortoiseshell cats, or '''torties''' for short,<ref name="WCF" /> combine two colours other than white in an asymmetrical distribution, either closely mixed ('brindled') or in larger patches.<ref name="Centerwall" /> The two colours always consist of one eumelanistic (black, blue, chocolate, lilac, cinnamon or fawn) and one phaeomelanistic (red or cream) colour. The most common tortoiseshell colouration is black tortoiseshell (black and red). Tortoiseshell can occur in combination with other cat coat patterns, such as tabby and colourpoints. Tortoiseshell cats with the tabby pattern in their eumelanistic colour are tortoiseshell tabby cats, sometimes referred to as '''torbies''' or '''torbie cats'''.<ref name="fanciers" /> Like the tricoloured tortoiseshell-and-white or calico (in North American English)<ref name="WCF">{{Cite web |title=Glossary of terms |url=https://wcf.de/en/glossary-of-terms/ |access-date=2026-03-03 |language=en-US|website=wcf.de|publisher=World Cat Federation}}</ref><ref name="Oxford">{{Cite web |title=Calico cat |url=https://www.oxfordlearnersdictionaries.com/definition/english/calico-cat |website=oxfordlearnersdictionaries.com |publisher=Oxford Learner's Dictionaries}}</ref> cats, tortoiseshell cats are almost exclusively female.<ref name="Centerwall">{{cite journal |last1=Centerwall |first1=W. R. |last2=Benirschke |first2=K. |date=1973 |title=Male Tortoiseshell and Calico (T-C) Cats: Animal models of sex chromosome mosaics, aneuploids, polyploids, and chimerics |journal=Journal of Heredity |volume=64 |issue=5 |pages=272–278 |doi=10.1093/oxfordjournals.jhered.a108410 |pmid=4798734}}</ref><ref>{{cite journal |last1=Centerwall |first1= W. R. |last2=Benirschke |first2=K. |title=An animal model for the XXY Klinefelter's syndrome in man: Tortoiseshell and calico male cats |journal=American Journal of Veterinary Research |volume=36 |issue=9 |pages=1275–1280 |date=1975 |doi= 10.2460/ajvr.1975.36.09.1275 |pmid=1163864}}</ref><ref>Atkins (2003), p. 61</ref><ref name="Colombo">{{Cite book |title=Feline Dermatology |date=2020 |publisher=Springer |last1=Noli |first1=Chiara |last2=Colombo |first2=Silvia |isbn=9783030298364 |location=Cham, Switzerland |oclc=1159164563}}</ref> Male tortoiseshells are rare and are usually sterile.<ref name="Colombo" /><ref name="Atkins 2003, p.105">Atkins (2003), p.105</ref> Tortoiseshell markings appear in many different cat breeds, as well as in non-purebred domestic cats.<ref name="Syufy">{{cite web |last=Syufy |first=Franny |url=https://www.thesprucepets.com/breeds-domestics-and-color-patterns-554862 |title=More Cat Colour Patterns: Calicos, Tortoiseshell, Tuxedo Cats |access-date=27 January 2025|website=thesprucepets.com}}</ref> This pattern is especially preferred in the Japanese Bobtail breed.<ref name="cat">{{cite web |publisher=Cat Fanciers' Association |title=Breed Profile: Japanese Bobtail |url=http://www.cfainc.org/breeds/profiles/japanese.html |access-date=2 June 2007 |url-status=dead |archive-url=https://web.archive.org/web/20070612084729/http://www.cfainc.org/breeds/profiles/japanese.html |archive-date=12 June 2007}}</ref>

== Pigmentation == {{Main|Cat coat genetics}} Tortoiseshell coats result from an interaction between genetic, developmental, and environmental factors. Coat colours in domestic cats are produced by the interaction of orange-based phaeomelanin (O) and black-based eumelanin (B) pigments.<ref name="genmodel" /> Tortoiseshell cats are bicoloured and expresses a combination of both next to each other in their coat. The primary gene for cat coat colour colouration (B) produces the brown-toned colours — black, blue, chocolate, lilac, cinnamon, and fawn. This gene can be masked by the co-dominant gene for the orange colour (O), which produces the orange-toned colours — red and cream. The orange gene is located on the X chromosome and has two alleles: orange (X^O) and non-orange (X^o), that produce the orange phaeomelanin and black eumelanin pigments, respectively. Typically, the alleles are notated as an uppercase '''O''' for orange, or a lowercase '''o''' for non-orange.<ref name="genmodel" />

thumb|upright=1|Cat with a blue ("dilute", "grey") tortoiseshell coat

{| class="wikitable" |+Pigment colour overview !Pigment ! colspan="2" |Allele<ref name="genmodel" /> !Gene<ref name="genmodel">{{Cite web |title=Genetic Model |url=https://wcf.de/en/genetic-model/ |access-date=2026-03-03 |language=en-US|website=wcf.de|publisher=World Cat Federation}}</ref> !Basic (D) !Dilution (d)<ref name="WCF" /> |- |'''phaeomelanin''' |orange |O | |red |cream |- | rowspan="3" |'''eumelanin''' | rowspan="3" |non-orange | rowspan="3" |o |B |black |blue |- |b |chocolate |lilac |- |b^l |cinnamon |fawn |}

The (B) and (O) genes can be further modified by a recessive dilute gene (dd) which softens the basic colours.<ref name="genmodel" /><ref>{{Citation |last=Crosta |first=Maria Cristina |title=Coat Colour Genetics |date=2020 |url=http://link.springer.com/10.1007/978-3-030-29836-4_2 |work=Feline Dermatology |pages=23–66 |editor-last=Noli |editor-first=Chiara |access-date=17 September 2023 |place=Cham, Switzerland |publisher=Springer International Publishing |doi=10.1007/978-3-030-29836-4_2 |isbn=9783030298357 |editor2-last=Colombo |editor2-first=Silvia|url-access=subscription }}</ref> Red becomes cream, black becomes blue, chocolate becomes lilac, and cinnamon becomes fawn.<ref name="WCF" /> All tortoiseshells form a combination of either two basic colours — red combined with black, chocolate or cinnamon — or two dilute colours — cream combined with blue, lilac or fawn. Therefore, a tortoiseshell cat may be a ''chocolate tortoiseshell'' (chocolate and red) or a ''blue tortoiseshell'' (blue and cream) or the like, based on the alleles for the (B) and (D) genes.<ref>{{Cite journal |last1=Moran |first1=Chris |last2=Gillies |first2=Chris B. |last3=Nicholas |first3=Frank W. |date=1984 |title=Fertile male tortoiseshell cats |url=https://academic.oup.com/jhered/article-lookup/doi/10.1093/oxfordjournals.jhered.a109964 |journal=Journal of Heredity |volume=75 |issue=5 |pages=397–402 |doi=10.1093/oxfordjournals.jhered.a109964 |issn=1465-7333|url-access=subscription }}</ref> However, due to genetic dominance, the most common tortoiseshell colouration is ''black tortoiseshell'' (black and red). Various terms are colloquially used for specific colours, for example, black is also called "brown", blue is also called "grey", red is also called "orange", "ginger", and "yellow".<ref name="Centerwall" /> Even though there exist three dilute tortoiseshell colours, blue is sometimes colloquially referred to as "dilute", which is the most common dilute colouration.

=== Sex linkage === Female cats are homogametic (XX) and undergo the phenomenon of X-inactivation,<ref>{{cite web |url= http://www.nature.com/scitable/topicpage/x-chromosome-x-inactivation-323 |title=X Chromosome: X Inactivation |work=Chromosomes and Cytogenetics |publisher=Nature Education |access-date=21 March 2011|date=2008|last=Ahn|first=J.|last2=Lee|first2=J.|series=1(1):24}}</ref> in which one of the X chromosomes is turned off at random in each cell in very early embryonic development.<ref>{{Cite journal |last=Lyon |first=Mary F. |date=22 April 1961 |title=Gene action in the X-chromosome of the mouse (''Mus musculus L.'') |url=https://www.nature.com/articles/190372a0 |journal=Nature |volume=190 |issue=4773 |pages=372–373 |doi=10.1038/190372a0 |bibcode=1961Natur.190..372L |issn=1476-4687|url-access=subscription }}</ref> The inactivated X becomes a Barr body. Cells in which the chromosome carrying the orange (O) allele is inactivated express the alternative non-orange (o) allele, determined by the (B) gene. Cells in which the non-orange (o) allele is inactivated express the orange (O) allele. Pigment genes are expressed in melanocytes that migrate to the skin surface later in development. In bicoloured tortoiseshell cats, the melanocytes arrive relatively early, and the two cell types become intermingled; this produces the characteristic brindled appearance consisting of an intimate mixture of orange and black cells, with occasional small diffuse spots of orange and black. Tortoiseshell cats have a combination of orange-based O and black-based o on two XX-chromosomes; labelled as X^OX^o, indicating O-gene heterozygosity.<ref name="WCF" /> Orange and black females have homozygous O-genes; labelled as X^OX^O (orange) and X^oX^o (black).

thumb|500x500px|Schematic overview of the sex linkage of the orange (O) and non-orange (o) allele|center

thumb|Typical combination of black- and red-based areas on the paw-pads of a tortoiseshell cat, in this case, in a mottling pattern

Male cats, like males of other therian mammals, are heterogametic (XY).<ref>{{Cite book |last=Gould |first=Laura |url=http://link.springer.com/10.1007/978-1-4684-6313-2 |title=Cats Are Not Peas |date=1996 |publisher=Springer |isbn=9781468463156 |location=New York |doi=10.1007/978-1-4684-6313-2}}</ref> The single X chromosome does not undergo X-inactivation, ergo coat colour is determined by which O-gene allele is present. Accordingly, the male cat's coat will be either entirely orange (O; X^OY ) or melanistic black (o; X^oY).

Leonard Doncaster was the first to prove sex linkage of the tortoiseshell coat colouration; i.e. that tortoiseshell is the female heterozygote of orange and black (X^OX^o) with the corresponding male being orange (X^OY). In the course of his studies he discovered that the rare tortoiseshell male is often sterile.<ref>{{cite journal |last=Bateson |first=W. |title=Prof. L. Doncaster, F.R.S. |journal=Nature |volume=105 |issue=2641 |pages=461–462 |date=10 June 1920 |doi=10.1038/105461a0|bibcode=1920Natur.105..461B |url= https://zenodo.org/record/1429638 |doi-access=free}}</ref><ref>{{Cite web |title=OMIA:001201-9685: Coat colour, orange in Felis catus (domestic cat) - OMIA - Online Mendelian Inheritance in Animals |url=https://omia.org/OMIA001201/9685/ |access-date=2026-03-02 |website=omia.org}}</ref>

Very rarely (approximately 1 in 3,000<ref>{{cite web |url= http://www.veterinarypartner.com/Content.plx?P=A&A=2209&S=5 |title=Feline Fallacies |work=The Pet Connection |publisher=VeterinaryPartner.com |first=Gina |last=Spadafori |archive-url= https://web.archive.org/web/20080612154655/http://www.veterinarypartner.com/Content.plx?P=A&A=2209&S=5 |access-date=3 July 2008 |archive-date=12 June 2008}}</ref>) a male tortoiseshell is born; these typically have an extra X chromosome (XXY), a condition known in humans as Klinefelter syndrome, and their cells undergo an X-inactivation process like in females. As in humans, these cats often are sterile because of the imbalance in sex chromosomes.<ref>{{Cite journal |last=Foster |first=Robert A |date=2022 |title=Disorders of sexual development in the cat: Current state of knowledge and diagnostic approach |journal=Journal of Feline Medicine and Surgery |volume=24 |issue=3 |pages=257–265 |doi=10.1177/1098612X221079711 |issn=1098-612X |pmc=9052703 |pmid=35209773}}</ref> Some male tortoiseshell cats may be chimaeras, which result from fusion in early development of two (fraternal twin) embryos with different colour genotypes; these torties can pass only one colour to their offspring, not both, according to which of the two original embryos its testes are descended from. Others are mosaics, in which the XXY condition arises after conception and the cat is a mixture of cells with different numbers of X chromosomes.

== Variations ==

=== Colour and distribution === Tortoiseshell cats have particoloured<ref name="WCF" /> coats; either bicoloured with parts of various shades of orange and non-orange pigments, or tricoloured in which tortoiseshell is combined with white spotting. The size of the patches can vary from a fine brindled pattern to large patched areas of colour. Typically, the higher degree of white spotting a cat has, the more distinct the different coloured patches are. In general, the markings on tortoiseshell cats are asymmetrically distributed.<ref name="fanciers">{{cite web |url= http://fanciers.com/other-faqs/colors.html#white_markings |title=Cat Colours FAQ: Common Colours |work=Fanciers.com |access-date=19 December 2015}}</ref> Dilution genes modify the colouring, lightening the coat colouration from red with either black, chocolate or cinnamon to a mix of cream with either blue, lilac or fawn. These three dilute tortoiseshell colours can be affected by a dilute modifier resulting in apricot mixed with their three caramel variants. Furthermore, the all tortoiseshell colours can occur in combination with the silver inhibitor gene, resulting in their respective silver tabby or smoke versions.

=== Tricolour (tortoiseshell-and-white) === {{Main|Calico cat}}

{{Multiple image | image1 = Short-haired tortoiseshell cat (cropped).jpg | image2 = Бассинда (13823156184) (cropped).jpg | direction = vertical | caption1 = "brindled" | header = Black tortoiseshell cats sporting different pigment distributions | caption2 = "patched"; In this case, the patches resulted in a double-centrefold face marking. Centrefold markings are often confused with chimaerism; however, in most cases, it is rather a less typical distribution of the tortoiseshell pattern. | caption_align = center | total_width = 254 | footer_background = #FFFFFF }}

In tricolour<ref name="WCF" /> cats, also known as tortoiseshell-and-white<ref name="WCF" /> or in North American English as calico,<ref name="WCF" /><ref name="Oxford" /> a separate gene interacts developmentally with the tortoiseshell coat colour genes. This white spotting gene<ref name="WCF" /> produces white, unpigmented patches by delaying the migration of the melanocytes to the skin surface. There are a number of alleles of this gene that produce greater or lesser delays. The amount of white is divided by cat registries into the categories ''mitted'', ''true bi- or tricolour'', ''harlequin'', and ''van'',<ref name="WCF" /> going from almost no white to almost completely white. In the extreme case, no melanocytes make it to the skin and the cat is entirely white, known as "epistatic" or "dominant white" (genetically different from albinism).<ref name="genmodel" /> In intermediate cases, melanocyte migration is slowed, so that the pigment cells arrive late in development and have less time to intermingle. Observation of tricolour cats will show that, with a little white colour, the orange and black patches become more defined, and with still more white, the patches become completely distinct. Each patch represents a clone of cells derived from one original cell in the early embryo.<ref name="RROB">{{cite book |last=Robinson |first=Roy |title=Genetics for Cat Breeders and Veterinarians |publisher=Butterworth-Heinemann Medical |date=1991 |isbn=9780750635400}}</ref>

center|thumb|600x600px|Schematic presentation of how white spotting affects tortoiseshell colour distribution. As the amount of white spotting increases, the tortoiseshell colour becomes less brindled and forms distinct patches of colour. This is related to the migration rates of pigment cells across the surface of the embryo.

=== Pattern === Apart from the different colour combinations the tortoiseshell pattern also occurs in combination with other genetic cat coat patterns. The phaeomelanistic red and cream colours will always show a tabby pattern, even if they are genetically "solid" or "self" (meaning non-agouti, i.e. non-tabby).<ref name="WCF" /> The eumelanistic colour (black, blue, chocolate, lilac, cinnamon, and fawn) makes it possible to visibly determine whether a tortoiseshell cat is tabby or solid. The tortoiseshell tabbies are often called ''tortie-tabby'', or ''torbie/y'' for short.<ref name="WCF" /> In North America the combination of calico and torby, ''caliby'', is used for tortoiseshell tabbies with large white areas.<ref name="fanciers" /> Tortoiseshell colouring can also be expressed in combination with one of the colourpoint restriction patterns, colloquially referred to as a ''tortie point''.<ref name="fanciers" />

== Folklore ==

In the folklore of several cultures, cats with tortoiseshell colouration are believed to bring good luck.<ref name="folklore">{{Cite journal |last=Bonnerjea |first=Biren |date=21 September 1935| title=Cats in Folklore and Belief |url= https://global.oup.com/academic/product/notes-and-queries-14716941?cc=us&lang=en& |journal=Notes and Queries |volume=CLXIX |pages=201–205 |doi=10.1093/nq/CLXIX.sep21.201 |via=Oxford University Press|url-access=subscription }}</ref> In Ireland, tortoiseshell cats are considered to bring good luck to their owners.<ref name="folklore" /> In the United States, tortoiseshells are sometimes referred to as ''money cats''.<ref>{{cite book |last1=Finegan |first1=Edward |last2=Rickford |first2=John |author-link2=John R. Rickford |url= http://www3.cambridge.org/uk/catalogue/catalogue.asp?isbn=0511206941&ss=fro |archive-url= https://archive.today/20130112142439/http://www3.cambridge.org/uk/catalogue/catalogue.asp?isbn=0511206941&ss=fro |url-status=dead |archive-date=12 January 2013 |title=Language in the USA: Themes for the Twenty-first Century |publisher=Cambridge University Press |date=2004 |access-date=22 January 2009 |isbn=0511206941}}</ref> In Japan, tortoiseshell cats are considered to bring good luck against shipwrecks.<ref name="folklore" /> There are some additional interpretations of the luck of tortoiseshell cats, such as the one in England that describes an announcement of misfortune when a strange tortoiseshell cat enters a house.<ref name="folklore" /> In England, if a woman dreams of a tortoiseshell cat, it can be interpreted as a warning that she should take care around her so-called friends.<ref name="folklore" />

== Behaviour == Some studies have found that people believe tortoiseshell cats are more likely to be aggressive and have owners report stronger prey interest<ref name="wilhelmy">{{cite journal |last1=Wilhelmy |first1=Jacquelene |last2=Serpell |first2=James |last3=Brown |first3=Dorothy |last4=Siracusa |first4=Carlo |title=Behavioural associations with breed, coat type, and eye colour in single-breed cats |date=2016 |journal=Journal of Veterinary Behaviour |volume=13 |issue=1 |pages=80–87|doi=10.1016/j.jveb.2016.03.009}}</ref><ref>{{Cite journal |last1=Stelow |first1=Elizabeth A. |last2=Bain |first2=Melissa J. |last3=Kass |first3=Philip H. |date=2 January 2016 |title=The Relationship Between Coat Colour and Aggressive Behaviours in the Domestic Cat |url= https://escholarship.org/content/qt4hf2b2st/qt4hf2b2st.pdf?t=o17125 |journal=Journal of Applied Animal Welfare Science |volume=19 |issue=1 |pages=1–15 |doi=10.1080/10888705.2015.1081820 |issn=1088-8705 |pmid=26467020|s2cid=7645478}}</ref> — the slang term "tortitude" was coined in reference to this perceived behaviour.<ref name="anthrozoos">{{cite journal |title=Human Perceptions of Coat Colour as an Indicator of Domestic Cat Personality |journal=Anthrozoös |year=2012 |last1=Delgado |first1=Mikel M. |last2=Munera |first2=Jacqueline D. |last3=Reevy |first3=Gretchen M. |volume=25 |issue=4 |pages=427–440 |doi=10.2752/175303712X13479798785779 |url=https://gwern.net/doc/cat/psychology/2012-delgado.pdf |access-date=2024-11-18 |quote=Tri-coloured cats (calicos and tortoiseshells) were ranked relatively high in aloofness and intolerance, and low in friendliness by the participants in this survey. The International Cat Association website describes them as follows: “They tend to have what the cat fancy calls ‘Tortie-tude.’ More than any other colour, these girls have an ‘opinion’ on everything” (The International Cat Association Southeast Region n.d.). A Google search for the term “Tortitude” (tortoiseshell attitude) brings up over 15,000 websites, many of which imply that tortoiseshell cats have unique personality traits including stubbornness, independence, and unpredictability. }}</ref> There is, however, little existing scientific evidence on the matter.<ref name="anthrozoos" /><ref>{{cite web |url=http://www.smithsonianmag.com/science-nature/judging-a-cat-wrongly-by-the-color-of-its-coat-97549864/?no-ist |title=Judging a Cat (Wrongly) by the Colour of its Coat |first=Sarah |last=Zielinski |work=Smithsonian |access-date=16 May 2015}}</ref> One study found that there was not a relationship between coat colour and tameness.<ref>{{Cite thesis |last=Umbelino |first=M. T. L. P. |date=2014 |title=Evaluation of the relation between tameness and coat colour in cats |type=PhD |publisher=University of Évora | url=https://core.ac.uk/download/pdf/62467987.pdf | access-date=2024-11-18 | quote=Despite our efforts to gain a better understanding of this relation in domestic cats, our study showed no significant relations between tameness and coat colour. However, we do believe a new study, with a larger sample and particular adjustments to the measuring scales would possibly find a strong relation between these two variables.}}</ref> Based on various study results, assumptions cannot be made between cat coat colour and personality.<ref name="Vonk">{{Cite book |title=Personality in Nonhuman Animals |last1=Vonk |first1=Jennifer |last2=Weiss |first2=Alexander |last3=Kuczaj |first3=Stan A. |date=26 July 2017 |isbn=9783319593005 |location=Cham, Switzerland |publisher=Springer |oclc=999445759}}</ref>{{pageneeded|date=February 2024}}

==Gallery== <gallery mode="packed" heights="200" class="center"> File:Tortoiseshellshorthair (2013 photo; cropped 2022).JPG|Black tortoiseshell ("tortie") File:路邊閒晃的貓_(49953930706).jpg|Black tortoiseshell tabby ("torbie/y") File:British shorthair with calico coat (2).jpg|Black tortoiseshell-and-white tricolour ("calico") File:Black tortoiseshell tabby and white cat side (cropped).jpg|Black tortoiseshell tabby-and-white tricolour ("caliby") File:Smudge 9472 (8467111276).jpg|Blue tortoiseshell tabby and white File:Tortie-point.jpg|Black colourpoint tortoiseshell ("tortie point") File:GIP HU Alba Regia Ganxsta Gizi (Gizi) BUR h female EX1 CAPS NOM.JPG|Chocolate tortoiseshell sepia Burmese File:Cat in Krasnodar, July, 2012 (square).jpg|Black smoke tortoiseshell domestic longhair File:KURILIAN BOBTAIL Femmina Jasmin (cropped).jpg|Black tortoiseshell silver blotched tabby Kurilian Bobtail Longhair File:High content black tortie.jpg|A female tortoiseshell cat with high black fur content </gallery>

== See also == * Calico cat * Deaf white cat * Tabby cat

==References== {{reflist|30em}}

* Atkins, Carla. ''Cats: An Owner's Guide'' (2003). San Diego, California: Thunder Bay Press. {{ISBN|1-59223-097-0}}

== External links == {{Commons category|Tortoiseshell cats}} {{Commons category|Tricolour cats}} * [http://messybeast.com/tricolours.htm Tortoiseshell and tricolour cats]

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