Cavy Genetics - Basics of the Breeds
Finding good information on breed and color genetics for cavies is MUCH more difficult than rabbits. The following is a compilation of what I've managed to pull together. Additional information/sources GREATLY appreciated! Written for the reader who already knows rabbit color genetics (or has at least read my rabbit color genetics 101).
The ARBA/ACBA Standard of Perfection recognizes cavies in 13 breeds. Differences among the breeds are not as pronounced as the differences among rabbit breeds -- in many cases a single gene mutation is responsible for the distinction between the breeds. Basic genetics suggest that crossing breeds would thus result in perfectly showable animals, but doing so is not generally recommended as hybrids often results in animals with intermediate characteristics or mismarkings (such as too few rosettes).
The ARBA/ACBA Standard of Perfection recognizes cavies in 13 breeds. Differences among the breeds are not as pronounced as the differences among rabbit breeds -- in many cases a single gene mutation is responsible for the distinction between the breeds. Basic genetics suggest that crossing breeds would thus result in perfectly showable animals, but doing so is not generally recommended as hybrids often results in animals with intermediate characteristics or mismarkings (such as too few rosettes).
Coat Length - L
Short coat (as in Americans, white crested, and teddies) is a dominant trait - designated L. Long coat (as in Silkes, Peruvians, Coronet and Texel) is recessive, designated l. Hybrids - Ll - usually have short coats, but may be slightly longer than the purebred LL.
Rosettes - R
The dominant R allele causes rosettes (as in Abyssinians and Peruvians). Breeds without rosettes (American, white crested, teddy, Silkie, texel, and coronet) are rr. Modifiers genes (separate, unknown genes) are needed to get the correct number and placement of rosettes. Abyssinians should have 10 rosettes. The long-haired 'sweeps' of Peruvians are also a modified rosette - only 6 are typical.
Star - St
The dominant Star allele (St) creates a single 'rosette' in the middle of the forehead (as in white crested and coronet). Breeds without the crest or coronet have the recessive genotype (stst). Additional modifier genes are responsible for the color and shape of the star. Hybrids (Stst) will have a coronet, but it is often poorly shaped due to the loss of the modifiers.
Teddy - T
The recessive teddy allele (t) causes a crimping in the hairs, resulting in a plush coat that stands on end. All other breeds have the dominant T- genotype.
Rex - Rx
The recessive rex allele (rx) causes a fur type similar to that of a rex or minirex rabbit. Longhaired cavies with the rxrx genotype (essentially silkies with rxrx rather than RxRx) are texels, which have long ringlets for fur. Shorthaired cavies with the rxrx genotype are called rexes - these are accepted in Britain and other countries, but not (yet) by the ACBA. Similarly, coronets with rxrx are called merinos and Peruvians with rxrx are called alpacas - none are (yet) accepted by ACBA.
Satin - Sn
The recessive satin allele (sn) imparts a glowing satin sheen to the coat - over and above the normal luster of the healthy coat. Satins are accepted in American satin, Abyssinian satin, Silkie Satin, Peruvian satin, and Teddy satin.
Breed Genotypes
Taking American as the 'base type':
American - L-rrststT-Sn-Rx-
Abyssinian - L-R-ststT-Sn-Rx- (American plus R [rosettes] and modifiers)
White crested - L-rrSt-T-Sn-Rx- (American plus St [star, crest or coronet] and modifiers)
Teddy - L-rrststttSn-Rx- (American plus tt [teddy])
Silkie - llrrststT-Sn-Rx- (long-haired American)
Peruvian - llR-ststT-Sn-Rx- (long haired Abyssinian with reduced rosettes)
Coronet - llrrSt-T-Sn-Rx- (long-haired white-crested [except other crest colors are allowed])
Texel - llrrststT-Sn-rxrx (Silkie with a ringlet coat, a cobby body and a broad face) [NOT a long-haired teddy, different gene responsible]
American satin - L-rrststT-snsnRx- (American plus the satin gene)
Abyssinian satin - L-R-ststT-snsnRx- (Abyssinian plus the satin gene)
Teddy satin - L-rrststttsnsnRx- (Teddy plus the satin gene)
Silkie satin - llrrststT-snsnRx- (Silkie plus the satin gene)
Peruvian satin - llR-ststT-snsnRx- (Peruvian plus the satin gene)
Other genetic combinations exist, but are not accepted by ARBA. Some are accepted elsewhere in the world. A few of the more common ones...
English crested -- unlike our White-crested, English crested are not required to have the modifier which turns the crest white. So the crest appears the same color as the body.
Rex - L-rrststT-Sn-rxrx (similar to a teddy, but slightly rougher texture)
Merino - llrrSt-T-Sn-rxrx (a coronet with ringlets - or a texel with a crest)
Alpaca - llR-ststT-Sn-rxrx (a curly Peruvian - or a texel with rosettes)
Somali - L-R-ststT-Sn-rxrx (a rex with rosettes)
Crested satins - L-rrSt-T-snsnRx-
Coronet satin - llrrSt-T-snsnRx-
Texel satin - llrrsrstT-snsnrxrx
Sheba Mini-Yak - llR-ststT-Sn-Rx- (a variation on Peruvian retaining more rosettes due to a recessive modifier resulting in a more 'tousled' appearance) crosses between abyssinians and longhaired cavies often result in an appearance closer to the sheba than to the Peruvian.
Ridgeback - L-R-ststT-Sn-Rx- (a variation on Abyssinian in which modifier genes restrict the rosettes to produce a single ridge along the spine)
Lunkarya - llrrststT-Sn-Rx- +Cu- a new gene discovered in Sweden (Cu) is the basis of the lunkarya, which looks like a texel with a looser curl. This is a separate gene from Rex or teddy, though with a similar 'rexoid' look.
Swiss (aka Swiss teddy) - L-rrststT-Sn-Rx- TWO separate novel genes. Recessive Sw (swiss) and a dominant semi-longhair gene combine to create a 'teddy' with an intermediate hair length (~3 inches) with a 'puffball' effect -- often the hair on the rear is longer than on the front.
Skinny - a separate recessive gene which causes cavies to be born (and remain) hairless. Skinny pigs often grow some sparse hair on the nose and feet. This gene originated in teddies, so many skinnies are hiding teddy genotypes.
Baldwin - a separate recessive gene which causes cavies to lose their hair (usually at a few weeks old). Baldwins originated in white-crested cavies and often hide white-crested genotypes. Skinny and Baldwin are separate genes -- crossing skinnies and baldwins results in cavies that have hair (but are carriers for both types of hairlessness).
Lakeland - a guinea pig which is born with teddy fur, loses it's hair at ~3 weeks old, and then regrows its hair. This is a carrier for the skinny gene. Not all skinny carriers are Lakelands, but all Lakelands are skinny carriers.
Werewolf - a guinea pig which is partially hairless - typically with more hair than a skinny. This is a genetic skinny pig, but has modifiers that allow some hair to remain or regrow. Typically born with more hair than usual for a skinny pig but often lose this extra hair in the first 3-4 weeks, then often re-grow it into adulthood. Hair may be affected hormonally - some skinnies grow hair only during pregnancy, some werewolves lose their hair following pregnancy.
Why don't we have rexes, merinos, alpacas, coronet satins or white crested satins?
ARBA/ACBA decided that a single gene difference (e.g., Rx and Sn) which are easily bred to the base type (as in breeding an American to an American satin) should not be sufficient to constitute a separate breed. Those breeds which had been accepted prior to this ruling (texel and the accepted satins) were grandfathered in - but no new satin or rex breeds will be accepted unless the rule changes.
Cavy Color Genetics
Way more genes, alleles and co-dominant traits, and gene interactions than with rabbits...hang on.
Black/Chocolate (B/b)
Simplest first. For those used to rabbit color genetics, let's do the B gene first. It comes in two forms (alleles). B for black and b for chocolate. Cavies that are BB or Bb are black, bb are chocolate (chocolate also adds a ruby glow to the eyes). Just like with rabbits, we can do lots of things with other genes to modify these two base colors.
Pattern Gene (A series)
Similar to the pattern series in rabbits, but we add an extra allele and change the rules just a bit.
A is the most dominant gene and results in an agouti animal very similar to the agouti pattern in rabbits -- rings of chestnut and black (with B-) or tan and chocolate (with bb) and a solid 'belly band' with just the chestnut/tan color.
Ar is recessive to A but dominant over the following alleles. Ar- animals look a lot like agoutis - until you flip them over. The ring pattern in these animals extends through the belly region, so the hair on the entire body looks the same. These animals are called solids.
At is the tan pattern allele. It gives you an animal that looks a LOT like a tan pattern rabbit - solid colored back (e.g., black or chocolate), tan belly, eyes circles and tan spots by the ears. Tan is dominant over self (the last allele in the series - below) but CO-dominant with A and Ar. Thus an animal with genotype AAt looks like an agouti except that you still get the tan eye circles and spots by the ears (a DQ'ed type). ArAt also looks like an agouti except you get the eye circles and pea spots (also a DQ). AtAt and Ata both give the tan pattern. Tans are currently accepted ONLY in American and teddy cavies.
a is the final allele in the series. Just like in rabbits, it is the self gene, resulting in a solid colored cavy.
So far:
AAB- and AArB- and AaB- = agouti
AAbb and AArbb and Aabb = chocolate agouti (accepted as one of several dilute agoutis)
ArArB- and AraB- = solids
ArArbb and Arabb = chocolate solid (accepted as one of several dilute solids)
AAtB- and AAtbb and ArAtB- and ArAtbb = unaccepted mismarked agouti and solids
AtAtB- and AtaB- = Black Tan (accepted in Americans and Teddies only)
AtAtbb and Atabb = Chocolate and Tan (accepted in Americans and Teddies only)
aaB- = self black
aabb = self chocolate
Prior to the addition of tan, the three A-alleles in cavies were treated as a simple dominance series. The A-series is actually entirely co-dominant. If the two alleles of a heterozygous pair (two different alleles in the same animal) give different instructions -- one to produce eumelanin (base color) and the other to produce phaeomelanin (the tan or white markings) - phaeomelanin always wins. The 'recessive' a allele codes only for eumelanin and will be overwritten by any other allele that calls for phaeomelanin. Since the solid allele (Ar) has phaeomelanin in fewer locations than agouti (A) and no phaeomelanin in any locations that A has eumelanin, the Ar allele acts as though it were recessive to A. But in the case of the tan allele (at), the tan pattern has phaeomelanin in places where the A and Ar have eumelanin (most notably the peaspots) as well as eumelanin in places where A and Ar have phaeomelanin (most of the coat except tipping).
CAUTION - with the rise of popularity in tan pattern cavies, breeders of agoutis and especially solids should be on the lookout for mismarked animals with peaspots. This is especially true for breeders of agoutis -- it is now increasingly possible to have a cavy sold as an agouti that is a genetic solid carrying tan -- Arat cavies appear agouti (except that it has peaspots which are small enough to be easily overlooked) even though they do NOT have any agouti genes!
A is the most dominant gene and results in an agouti animal very similar to the agouti pattern in rabbits -- rings of chestnut and black (with B-) or tan and chocolate (with bb) and a solid 'belly band' with just the chestnut/tan color.
Ar is recessive to A but dominant over the following alleles. Ar- animals look a lot like agoutis - until you flip them over. The ring pattern in these animals extends through the belly region, so the hair on the entire body looks the same. These animals are called solids.
At is the tan pattern allele. It gives you an animal that looks a LOT like a tan pattern rabbit - solid colored back (e.g., black or chocolate), tan belly, eyes circles and tan spots by the ears. Tan is dominant over self (the last allele in the series - below) but CO-dominant with A and Ar. Thus an animal with genotype AAt looks like an agouti except that you still get the tan eye circles and spots by the ears (a DQ'ed type). ArAt also looks like an agouti except you get the eye circles and pea spots (also a DQ). AtAt and Ata both give the tan pattern. Tans are currently accepted ONLY in American and teddy cavies.
a is the final allele in the series. Just like in rabbits, it is the self gene, resulting in a solid colored cavy.
So far:
AAB- and AArB- and AaB- = agouti
AAbb and AArbb and Aabb = chocolate agouti (accepted as one of several dilute agoutis)
ArArB- and AraB- = solids
ArArbb and Arabb = chocolate solid (accepted as one of several dilute solids)
AAtB- and AAtbb and ArAtB- and ArAtbb = unaccepted mismarked agouti and solids
AtAtB- and AtaB- = Black Tan (accepted in Americans and Teddies only)
AtAtbb and Atabb = Chocolate and Tan (accepted in Americans and Teddies only)
aaB- = self black
aabb = self chocolate
Prior to the addition of tan, the three A-alleles in cavies were treated as a simple dominance series. The A-series is actually entirely co-dominant. If the two alleles of a heterozygous pair (two different alleles in the same animal) give different instructions -- one to produce eumelanin (base color) and the other to produce phaeomelanin (the tan or white markings) - phaeomelanin always wins. The 'recessive' a allele codes only for eumelanin and will be overwritten by any other allele that calls for phaeomelanin. Since the solid allele (Ar) has phaeomelanin in fewer locations than agouti (A) and no phaeomelanin in any locations that A has eumelanin, the Ar allele acts as though it were recessive to A. But in the case of the tan allele (at), the tan pattern has phaeomelanin in places where the A and Ar have eumelanin (most notably the peaspots) as well as eumelanin in places where A and Ar have phaeomelanin (most of the coat except tipping).
CAUTION - with the rise of popularity in tan pattern cavies, breeders of agoutis and especially solids should be on the lookout for mismarked animals with peaspots. This is especially true for breeders of agoutis -- it is now increasingly possible to have a cavy sold as an agouti that is a genetic solid carrying tan -- Arat cavies appear agouti (except that it has peaspots which are small enough to be easily overlooked) even though they do NOT have any agouti genes!
Pink-eyed Dilute (Pp)
Unlike with rabbits, pink eyes aren't restricted to white animals. The recessive p gene lightens the black portions of the coat color (but not all the way to white) and causes pink eyes. It doesn't lighten red portions of the coat.
Lets start with the selfs (aa) - Black becomes lilac (unlike rabbits, where lilac is the dilute of chocolate, in cavies lilac is the pink-eyed dilute for black) and chocolate becomes beige (with pink eyes).
So...
Black = aaB-P-
Chocolate = aabbP-
Lilac = aaB-pp
beige = aabbpp
Let's tackle tan combinations next..
AtAtB-P- and AtaB-P- = Black tan
AtAtbbP- and AtabbP- = Chocolate tan
AtAtB-pp and AtaB-pp = Lilac tan
AtAtbbpp and Atabbpp = beige tan
[tans accepted only in Americans and teddies]
Solids with dark eyes
A-B-P- = agouti
A-bbP- = dilute agouti (dark eyes) (chocolate agoutis)
Ar-B-P- = solid
Ar-bbP- = dilute solid (dark eyes) (chocolate agoutis)
Solid Pink-eyed dilutes
A-B-pp = dilute agouti (pink eyes) (lilac agoutis)
A-bbpp = dilute agouti (pink eyes) (Beige agoutis)
Ar-B-pp = dilute solid (pink eyes) (lilac agoutis)
Ar-bbpp = dilute solid (pink eyes) (Beige agoutis)
Note - Dilute agoutis and solids are shown as a group with only a subset of color combinations acceptable.
Please note - In cavies the eye color caused by the pink-eyed dilute gene (pp) or the himalayan gene (below ch) is referred to as PINK-eyed - even though it looks pretty much identical to what we would call 'RED-eyed white' in rabbits. This is most likely because in cavies the cr gene causes RED eyes of a deep red shade (closer to what we call 'ruby cast' in rabbits). In rabbits, red eyes are found only in whites and himalayans and are due to the action of either the himalayan (ch) or albino (c) gene -- both on the C-series. In cavies, pink-eyes are due to EITHER the p gene (described here) or the himalayan gene (ch - described below) - the true albino gene c does not exist in cavies.
The blue tan color recently accepted in American cavies is attributed to a genotype pgpg - which is an intermediate allele in the P series.
P>pg>p
The pg allele lightens black to a slate-blue color intermediate between black and lilac. It lightens chocolate to a caramel color intermediate between chocolate and beige. The pg allele lightens eye color to a slate-grey or deep ruby (NOT blue). In the US, ACBA accepts the pgpg genotype ONLY in blue tan and marten americans and teddies. NO caramels are accepted.
The US is the only place in the cavy world to refer to this color as blue. Elsewhere it is called slate. The rest of the cavy world reserved the term 'blue' in the hopes that someday a D-mutation (giving blue-grey eyes) would arise. Their patience has paid off as a new mutation found in tortoiseshells in Sweden appears to be true blue (dd) - but lots of work still needs to be done to confirm that.
Lets start with the selfs (aa) - Black becomes lilac (unlike rabbits, where lilac is the dilute of chocolate, in cavies lilac is the pink-eyed dilute for black) and chocolate becomes beige (with pink eyes).
So...
Black = aaB-P-
Chocolate = aabbP-
Lilac = aaB-pp
beige = aabbpp
Let's tackle tan combinations next..
AtAtB-P- and AtaB-P- = Black tan
AtAtbbP- and AtabbP- = Chocolate tan
AtAtB-pp and AtaB-pp = Lilac tan
AtAtbbpp and Atabbpp = beige tan
[tans accepted only in Americans and teddies]
Solids with dark eyes
A-B-P- = agouti
A-bbP- = dilute agouti (dark eyes) (chocolate agoutis)
Ar-B-P- = solid
Ar-bbP- = dilute solid (dark eyes) (chocolate agoutis)
Solid Pink-eyed dilutes
A-B-pp = dilute agouti (pink eyes) (lilac agoutis)
A-bbpp = dilute agouti (pink eyes) (Beige agoutis)
Ar-B-pp = dilute solid (pink eyes) (lilac agoutis)
Ar-bbpp = dilute solid (pink eyes) (Beige agoutis)
Note - Dilute agoutis and solids are shown as a group with only a subset of color combinations acceptable.
Please note - In cavies the eye color caused by the pink-eyed dilute gene (pp) or the himalayan gene (below ch) is referred to as PINK-eyed - even though it looks pretty much identical to what we would call 'RED-eyed white' in rabbits. This is most likely because in cavies the cr gene causes RED eyes of a deep red shade (closer to what we call 'ruby cast' in rabbits). In rabbits, red eyes are found only in whites and himalayans and are due to the action of either the himalayan (ch) or albino (c) gene -- both on the C-series. In cavies, pink-eyes are due to EITHER the p gene (described here) or the himalayan gene (ch - described below) - the true albino gene c does not exist in cavies.
The blue tan color recently accepted in American cavies is attributed to a genotype pgpg - which is an intermediate allele in the P series.
P>pg>p
The pg allele lightens black to a slate-blue color intermediate between black and lilac. It lightens chocolate to a caramel color intermediate between chocolate and beige. The pg allele lightens eye color to a slate-grey or deep ruby (NOT blue). In the US, ACBA accepts the pgpg genotype ONLY in blue tan and marten americans and teddies. NO caramels are accepted.
The US is the only place in the cavy world to refer to this color as blue. Elsewhere it is called slate. The rest of the cavy world reserved the term 'blue' in the hopes that someday a D-mutation (giving blue-grey eyes) would arise. Their patience has paid off as a new mutation found in tortoiseshells in Sweden appears to be true blue (dd) - but lots of work still needs to be done to confirm that.
Non-extension - E series
Similar to rabbits in that this is how to get red color, but works a bit differently!
E is the dominant allele - EE results in the normal colors above.
ee is the recessive. As with rabbits, it extends the middle band and removes the base (black/chocolate) color. Does not remove dark eye color.
As in rabbits, A-ee gives red. So does Ar-ee. Unlike rabbits, so does At-ee (no fox, just red). Also unlike rabbits, so does aaee (no tort, just red).
In cavies, aaee is the preferred genotype for red-based colors. Reds with A, Ar or at often have some dark pigment (smut) on their ears.
Under the ACBA standard, the non-extension 'reds' are broken into subgroups based on the 'dilution' (combination of B, C and P genes): red, red-eyed orange, gold, and cream (see below)
We've also got an intermediate allele in play - Ep or partial extension.
aaB-P-EpEp gives a color that is called tortoiseshell in cavies (but is what we would call harlequin in rabbits) in which the animal has patches of black and orange (requires some additional modifiers to make the patches look right) OR (depending on modifiers) can give brindle (interspersed black and red hairs).
With chocolate, dilutes (pink-eyed above or C series below), agouti, or solid, EpEp is called broken (broken in cavies can be any two or more colors, not just a color and white). Adding EpEp to tan (At-) usually leaves small tan marks, which are not accepted.
Note that so far, I've just given the 'pure' E series genotypes - EE, EpEp and ee. That's because the dominance in this series isn't so simple.
Eep animals often (but not always) have stray red marks (like Vienna carriers and Vienna marks in rabbits). Some breeders of brindles report the Eep brindles can often not be distinguished from good brindles other than a tendency to throw a significant number solid black babies (even when there is no other possible source for an E-gene, such as brindle x brindle).
Ee can also (less commonly and smaller when present) also result in stray red marks.
Epe pretty much looks like EpEp -- since the Ep already causes red patches, its hard to tell whether or not the e is adding a few extra - but sources argue that an Epe cavy will be 'more red' than the EpEp.
Recap - Like rabbits, the E series gene is responsible for red color. But it works much more like the rabbit Vienna (BEW) gene - completely covering other colors and patterns and, when 'carried,' occasionally showing though as stray marks.
E is the dominant allele - EE results in the normal colors above.
ee is the recessive. As with rabbits, it extends the middle band and removes the base (black/chocolate) color. Does not remove dark eye color.
As in rabbits, A-ee gives red. So does Ar-ee. Unlike rabbits, so does At-ee (no fox, just red). Also unlike rabbits, so does aaee (no tort, just red).
In cavies, aaee is the preferred genotype for red-based colors. Reds with A, Ar or at often have some dark pigment (smut) on their ears.
Under the ACBA standard, the non-extension 'reds' are broken into subgroups based on the 'dilution' (combination of B, C and P genes): red, red-eyed orange, gold, and cream (see below)
We've also got an intermediate allele in play - Ep or partial extension.
aaB-P-EpEp gives a color that is called tortoiseshell in cavies (but is what we would call harlequin in rabbits) in which the animal has patches of black and orange (requires some additional modifiers to make the patches look right) OR (depending on modifiers) can give brindle (interspersed black and red hairs).
With chocolate, dilutes (pink-eyed above or C series below), agouti, or solid, EpEp is called broken (broken in cavies can be any two or more colors, not just a color and white). Adding EpEp to tan (At-) usually leaves small tan marks, which are not accepted.
Note that so far, I've just given the 'pure' E series genotypes - EE, EpEp and ee. That's because the dominance in this series isn't so simple.
Eep animals often (but not always) have stray red marks (like Vienna carriers and Vienna marks in rabbits). Some breeders of brindles report the Eep brindles can often not be distinguished from good brindles other than a tendency to throw a significant number solid black babies (even when there is no other possible source for an E-gene, such as brindle x brindle).
Ee can also (less commonly and smaller when present) also result in stray red marks.
Epe pretty much looks like EpEp -- since the Ep already causes red patches, its hard to tell whether or not the e is adding a few extra - but sources argue that an Epe cavy will be 'more red' than the EpEp.
Recap - Like rabbits, the E series gene is responsible for red color. But it works much more like the rabbit Vienna (BEW) gene - completely covering other colors and patterns and, when 'carried,' occasionally showing though as stray marks.
The Dilution Gene - C series
Not at all like either the dilution gene (D series) nor the C series in rabbits. But it has an effect somewhat similar.
Point #1 - the C series alleles all have a similar effect - lightening pigment color. They can operate on the fur color, the eye color or both.
Point #2 - C, the 'normal color' allele is dominant and can hide any of the others.
Point #3 - the rest of the whole series is co-dominant - mixing alleles gives you intermediate degrees of dilution.
The alleles
C is the normal color (as dictated by ABE and P genes)
ck is dark dilute. It lightens the coat a bit, but not the eyes (unless combined with pp).
cd is the light dilute (aka buff dilute). It lightens the coat significantly more but leaves the eyes dark (unless combined with pp, which lightens the eyes)
cr is the ruby eyed dilute (aka Dark-eyed white dilute). It lightens the coat to white or near white and shifts the eyes to a ruby red (dark eyes with a ruby cast, not pink).
ch is the himi gene, responsible for both himalayans and pink-eyed whites.
I'm going to start with the 'most recessive' lightest color first - ch.
Black + chch = aaB-P-E-chch = himalayan - as with the rabbit of that name, the result is a white cavy with black points (nose, ears, feet).
Chocolate + chch = aabbP-E-chch = chocolate himalayan (can be shown, but the black preferred)
lilac/beige + chch = aa--ppE-chch = eye color fades to pink - point color often fades to white.
Red + chch = white (pink eyes acceptable in white). [I believe this includes all the reds that were agouti, solid and tan as well as the selfs]
Agouti/solid +chch = Not showable (himalayan with very poor points)
I find precious few mentions of the ruby-eyed gene (cr). It's definitely responsible for the dark-eyed whites (aabbP-eecrcr and aaB-P-eecrcr). It is also responsible for the silver agoutis and silver solids. Added to a tan pattern, it results in the marten. It may also be responsible for the ruby cast mentioned as acceptable in the following varieties: chocolate, cream, red, some dilute agoutis and solids, dalmatian.
crch genotypes result in a slight lightening of the coat except over the points and a ruby cast to the eyes. In it's purest form, this color is referred to as sable. Sables are not accepted in the US (here they are just considered to be 'uneven colored selfs' and often disqualified for the ruby cast eyes) - but are accepted elsewhere in the world.
The ck and cd alleles produce color dilutions that don't affect eye color and are definitely co-dominant (interacting with one another).
ck/cd dilutions change black to silver and lemon and chocolate to cinnamon and cream (not accepted as selfs, but possible as dilute agoutis - below)
ck/cd dilutions lighten the shade of lilac and beige selfs - these lighter shades are typically preferred.
They interact with the non-extension series to produce lighter shades that are recognizably (and accepted as) different...
black & lilac based reds lighten to golds (--B---eecxcx)
chocolate-based reds (--bbP-eecxcx) lighten to cream.
beige-based reds (aabbppeecxcx) lighten to red-eyed orange (ckcd) or pink-eyed cream (cdch)
A quick note on albino - The true albino gene (a recessive usually symboled c) which all by itself (without the assistance of any other gene) completely shuts down the production of pigments (both eumelanin and phaeomelanin) is unknown in cavies. Although the red-eyed white of rabbits LOOKS identical to the pink-eyed white of cavies, REW rabbits are true genetic albinos, while PEW cavies are not.
Point #1 - the C series alleles all have a similar effect - lightening pigment color. They can operate on the fur color, the eye color or both.
Point #2 - C, the 'normal color' allele is dominant and can hide any of the others.
Point #3 - the rest of the whole series is co-dominant - mixing alleles gives you intermediate degrees of dilution.
The alleles
C is the normal color (as dictated by ABE and P genes)
ck is dark dilute. It lightens the coat a bit, but not the eyes (unless combined with pp).
cd is the light dilute (aka buff dilute). It lightens the coat significantly more but leaves the eyes dark (unless combined with pp, which lightens the eyes)
cr is the ruby eyed dilute (aka Dark-eyed white dilute). It lightens the coat to white or near white and shifts the eyes to a ruby red (dark eyes with a ruby cast, not pink).
ch is the himi gene, responsible for both himalayans and pink-eyed whites.
I'm going to start with the 'most recessive' lightest color first - ch.
Black + chch = aaB-P-E-chch = himalayan - as with the rabbit of that name, the result is a white cavy with black points (nose, ears, feet).
Chocolate + chch = aabbP-E-chch = chocolate himalayan (can be shown, but the black preferred)
lilac/beige + chch = aa--ppE-chch = eye color fades to pink - point color often fades to white.
Red + chch = white (pink eyes acceptable in white). [I believe this includes all the reds that were agouti, solid and tan as well as the selfs]
Agouti/solid +chch = Not showable (himalayan with very poor points)
I find precious few mentions of the ruby-eyed gene (cr). It's definitely responsible for the dark-eyed whites (aabbP-eecrcr and aaB-P-eecrcr). It is also responsible for the silver agoutis and silver solids. Added to a tan pattern, it results in the marten. It may also be responsible for the ruby cast mentioned as acceptable in the following varieties: chocolate, cream, red, some dilute agoutis and solids, dalmatian.
crch genotypes result in a slight lightening of the coat except over the points and a ruby cast to the eyes. In it's purest form, this color is referred to as sable. Sables are not accepted in the US (here they are just considered to be 'uneven colored selfs' and often disqualified for the ruby cast eyes) - but are accepted elsewhere in the world.
The ck and cd alleles produce color dilutions that don't affect eye color and are definitely co-dominant (interacting with one another).
ck/cd dilutions change black to silver and lemon and chocolate to cinnamon and cream (not accepted as selfs, but possible as dilute agoutis - below)
ck/cd dilutions lighten the shade of lilac and beige selfs - these lighter shades are typically preferred.
They interact with the non-extension series to produce lighter shades that are recognizably (and accepted as) different...
black & lilac based reds lighten to golds (--B---eecxcx)
chocolate-based reds (--bbP-eecxcx) lighten to cream.
beige-based reds (aabbppeecxcx) lighten to red-eyed orange (ckcd) or pink-eyed cream (cdch)
A quick note on albino - The true albino gene (a recessive usually symboled c) which all by itself (without the assistance of any other gene) completely shuts down the production of pigments (both eumelanin and phaeomelanin) is unknown in cavies. Although the red-eyed white of rabbits LOOKS identical to the pink-eyed white of cavies, REW rabbits are true genetic albinos, while PEW cavies are not.
A note on the dilute agoutis and solids
ACBA accepts 10 color combinations in the category of dilute agouti (and dilute solid) these are achieved by combining the chocolate gene (b), pink-eyed dilute gene (p), the buff dilute gene (cd), and the ruby-eyed dilute gene (cr). All must be E- (ee turns completely red or white!).
Black series (BBP-)
with C- is not diluted at all - golden agouti = A-B-P-C-E- (shown as its own group)
lemon agouti (black with cream tips and dark eyes) - A-B-P-cd-E- (shown as part of the dilute agouti group)
Note the cr dilution here is called silver agouti - A-B-P-cr-E- (shown as its own group rather than part of the dilutes)
Chocolate series (bbP-)
chocolate agouti (chocolate with red tips and dark eyes with a ruby cast) - A-bbP-C-
cream agouti (chocolate with cream tips and dark eyes with a ruby cast) - A-bbP-cd-
cinnamon agouti (chocolate with white tips and dark eyes with a ruby cast) - A-bbP-cr-
Lilac Series (B-pp)
gold/lilac argente (lilac with orange tips and pink eyes) - A-B-ppC-
lemon/lilac argente (lilac with cream tips and pink eyes) - A-B-ppcd-
white lilac argente (lilac with white tips and pink eyes) - A-B-ppcr-
Beige series (bbpp)
gold/beige argente (beige with orange tips and pink eyes) - A-bbppC-
lemon/beige argente (beige with cream tips and pink eyes) - A-bbppcd-
white/beige argente (beige with white tips and pink eyes) - A-bbppcr-
For solids, replace the word agouti/argente with solid and the A- with Ar-. Keep in mind a dilute solid (Ar-) is NOT a dilute self (aa)! Solids have the same color hairs over their whole body, but each hair is made of two colors - base and tip.
Black series (BBP-)
with C- is not diluted at all - golden agouti = A-B-P-C-E- (shown as its own group)
lemon agouti (black with cream tips and dark eyes) - A-B-P-cd-E- (shown as part of the dilute agouti group)
Note the cr dilution here is called silver agouti - A-B-P-cr-E- (shown as its own group rather than part of the dilutes)
Chocolate series (bbP-)
chocolate agouti (chocolate with red tips and dark eyes with a ruby cast) - A-bbP-C-
cream agouti (chocolate with cream tips and dark eyes with a ruby cast) - A-bbP-cd-
cinnamon agouti (chocolate with white tips and dark eyes with a ruby cast) - A-bbP-cr-
Lilac Series (B-pp)
gold/lilac argente (lilac with orange tips and pink eyes) - A-B-ppC-
lemon/lilac argente (lilac with cream tips and pink eyes) - A-B-ppcd-
white lilac argente (lilac with white tips and pink eyes) - A-B-ppcr-
Beige series (bbpp)
gold/beige argente (beige with orange tips and pink eyes) - A-bbppC-
lemon/beige argente (beige with cream tips and pink eyes) - A-bbppcd-
white/beige argente (beige with white tips and pink eyes) - A-bbppcr-
For solids, replace the word agouti/argente with solid and the A- with Ar-. Keep in mind a dilute solid (Ar-) is NOT a dilute self (aa)! Solids have the same color hairs over their whole body, but each hair is made of two colors - base and tip.
White Spotted - S/s
The white spotted gene is a co-dominant gene used in the Dutch, broken and tortoiseshell & white varieties. Its a pretty straightforward co-dominant system...SS is the 'normal' genotype with no white spots. Ss produces an animal with less than 50% white -- anywhere from a small spot up to half white. ss produces an animal that is more than 50% white. Rarely, this may give an all white animal, but most often you get a white cavy with spots of color. Exactly how much white (within the ranges above) as well as the pattern of the white patches are determined by modifier genes.
Broken is the most basic color pattern to rely on the white-spotted gene (note for cavies, color combinations NOT including white - and so not using this gene - are also called and shown as broken). Showable broken cavies in white + color (and the color can be any self, red, agouti or solid - but not tan) must have a white patch at least as large as a 50 cent piece. The preferred (i.e., needed to win) patterns are those close to 50-50 (half white, half colored) with large patches. The truly ideal approaches the pattern we call harlequin in rabbits (only in this case colored and white). Winning broken cavies can thus be either Ss or ss but are unlikely to be produced at random (requires very careful selection from broken lines to get those ideal patches).
Tortoiseshell and white cavies (and other tri-colored cavies which are shown as brokens) also have the white-spotted gene in play along with the Ep gene (harlequin - see above). As tri-colored cavies should ideally have just 1/3 of their color white, they should be all Ss. Again modifier genes are critical to get the preferred (winning) patterns.
Dutch marked cavies look a lot like Dutch rabbits. The Ss genotype gives the Dutch pattern, but again, modifiers are needed to get the marks in the right places, so you are unlikely to produce a Dutch-marked cavy out of brokens that aren't out of Dutch lines. Black Dutch are EE and red Dutch are ee.
Broken is the most basic color pattern to rely on the white-spotted gene (note for cavies, color combinations NOT including white - and so not using this gene - are also called and shown as broken). Showable broken cavies in white + color (and the color can be any self, red, agouti or solid - but not tan) must have a white patch at least as large as a 50 cent piece. The preferred (i.e., needed to win) patterns are those close to 50-50 (half white, half colored) with large patches. The truly ideal approaches the pattern we call harlequin in rabbits (only in this case colored and white). Winning broken cavies can thus be either Ss or ss but are unlikely to be produced at random (requires very careful selection from broken lines to get those ideal patches).
Tortoiseshell and white cavies (and other tri-colored cavies which are shown as brokens) also have the white-spotted gene in play along with the Ep gene (harlequin - see above). As tri-colored cavies should ideally have just 1/3 of their color white, they should be all Ss. Again modifier genes are critical to get the preferred (winning) patterns.
Dutch marked cavies look a lot like Dutch rabbits. The Ss genotype gives the Dutch pattern, but again, modifiers are needed to get the marks in the right places, so you are unlikely to produce a Dutch-marked cavy out of brokens that aren't out of Dutch lines. Black Dutch are EE and red Dutch are ee.
Roan - Rn
Roan is a co-dominant gene. The 'normal' cavy colors all have the recessive genotype rnrn. Rnrn produces a roan kit in which the colored and white hairs are mixed together producing a speckled pattern. RnRn produces white pups with ruby-blue eyes, called 'lethal whites'. Unfortunately, RnRn kits earn the name 'lethal' -- often blind, with twisted teeth and other deformities. In most cases, these deformities are severe enough to limit quality of life and lethals should be put down. For this reason, roans should always be bred with a solid colored cavy (in the color you are trying to include in the roan) and never with another roan. This is the same type of breeding pattern we use in broken rabbits (breed broken to solid) when we try to avoid producing the unshowable charlies. But here it is much more serious as those deformed pups have to be put down.
Dalmatian is a variation on roan - in the US addition of some modifier genes cause the colored hairs to cluster into spots rather than mix evenly through the coat. There may be an alternative allele at the same locus that is more common in European dalmatians. Because the roan gene (or at least gene locus) is involved, you should never breed dalmatian to dalmatian or dalmatian to roan either.
Dalmatian is a variation on roan - in the US addition of some modifier genes cause the colored hairs to cluster into spots rather than mix evenly through the coat. There may be an alternative allele at the same locus that is more common in European dalmatians. Because the roan gene (or at least gene locus) is involved, you should never breed dalmatian to dalmatian or dalmatian to roan either.
