2 Pups 1 Sac Different Sex

[megan_]

How do you know they are identical rather than just twins?

[OSoSwift]

It was said before there was one sack and one placenta

[Rebanne]

As a result of her genetic abnormality, the girl will suffer from Turner syndrome, which is distinguishable by short stature, folds of skin at the neck, abnormal development of secondary sexual characteristics, and an intellectual deficit known as space-form blindness . Turner syndrome can occur in any birth (including singletons, fraternal female twins, or identical female twins), so an individual with Turner syndrome is not automatically a twin. Turner syndrome occurs in about 1 in 10,000 of all births, but cases of mixed sex identical twins are much rarer—only three cases have been documented.

what will you do with this female puppy?

[Dame Aussie]

I have no advice but they are BEAUTIFUL

[YOLO]

well thats what i always thought too but they defiantly were both in the one sac with one placenta

These are Monochorionic twins (same sac & placenta) but not necessarily Monozygotic (identical.) This is not uncommon in litters. In some cases this can lead to Twin-to-twin transfusion, which in litters can be one cause of a runt. As for your two having a special bond, they would presumably share many things in common, and would have grown accustomed to close contact with eachother and possibly recognise each other’s tastes and scent.

However, as other people have said, it is possible that this is a rare case of mosonomy, where the twins are identical but one is missing all or part of the y chromozone. (In which case the girl would probably be sterile.)

[Kinkykaters]

well thats what i always thought too but they defiantly were both in the one sac with one placenta

These are Monochorionic twins (same sac & placenta) but not necessarily Monozygotic (identical.) This is not uncommon in litters. In some cases this can lead to Twin-to-twin transfusion, which in litters can be one cause of a runt. As for your two having a special bond, they would presumably share many things in common, and would have grown accustomed to close contact with eachother and possibly recognise each other’s tastes and scent.

However, as other people have said, it is possible that this is a rare case of mosonomy, where the twins are identical but one is missing all or part of the y chromozone. (In which case the girl would probably be sterile.)

Thank you! very informative!

[Pawfect]

In the described (improbable) case, the male would be XYY if the female is in fact XO & otherwise identical?

I read something about people with XYY are more likely to be in prisons & mental institutions (lower IQ, emotionally immature, impulsive).

Quiet interesting!

Edited March 21, 2013 by Pawfect

[inez]

In extremely rare cases, identical twins have been born with opposite sexes (one male, one female). In these cases, identical twin boys are conceived, but, during the twinning process, one twin loses a Y chromosome (boys have chromosome type XY while girls have XX). Without a Y chromosome to trigger the production of male sex hormones , this fetus develops as a girl by default, but a girl with only one X chromosome (chromosome type XO). The co-twin is unaffected, and develops as a boy as normal.

I read this about humans but i haven't been able to find any thing about it with dogs

so do the girls grow up to be 'full' girls with only one X chromosome?

The occurance of what is called Freemartin in heifers born with a twin brother, is that a percentage of them the hormones of the male calf interfere with the normal growth of the female organs so they do not develop normally. During an AI course in cattle the lecturer had worked at Gatton Research Centre and told us that at Gatton when he was working there they had trialed to determine which females were a freemartin discovered that if a pencil sized instrument could be inserted into the vagina of the newborn calf easily she would not mature into a freemartin. if it couldnt she would be a freeartin.

I have not heard of this condition referred to in anything but cattle.

"A freemartin or free-martin (sometimes martin heifer) is an infertile female mammal which has masculinized behavior and non-functioning ovaries.[1] Genetically the animal is chimeric: karyotyping of a sample of cells shows XX/XY chromosomes. [The animal originates as a female (XX), but acquires the male (XY) component in utero by exchange of some cellular material from a male twin, via vascular connections between placentas.] Externally, the animal appears female, but various aspects of female reproductive development are altered due to acquisition of anti-Müllerian hormone from the male twin.[2] Freemartinism is the normal outcome of mixed-sex twins in all cattle species that have been studied, and it also occurs occasionally in other mammals including sheep, goats and pigs.

The 18th-century physician John Hunter discovered that a freemartin always has a male twin.[3]

It was hypothesized early in the 20th century that masculinizing factors travel from the male twin to the female twin through the vascular connections of the placenta because of the vascular fusion and affect the internal anatomy of the female.[4]

Several researchers made the discovery that a freemartin results when a female fetus has its chorion fuse in the uterus with that of a male twin. The result was published in 1916 by Tandler and Keller.[5] The discovery was made independently by American biologist Frank R. Lillie, who published it in Science in 1916.[6] Both teams are now credited with the discovery.[7]

In rural areas folklore often claimed this condition was not just peculiar to cattle, but extended also to human twins; this belief perpetuated for generations, as was mentioned in the writings of Bede.[8]

In most cattle twins, the blood vessels in the chorions become interconnected, allowing blood from each twin to flow around the other. If both fetuses are the same sex this is of no significance, but if they are different, male hormones pass from the male twin to the female twin. The male hormones then masculinize the female twin, and the result is a freemartin.[9] The degree of masculinization is greater if the fusion occurs earlier in the pregnancy – in about ten percent of cases no fusion takes place and the female remains fertile.

The male twin is largely unaffected by the fusion, although the size of the testicles may be slightly reduced. Testicle size is associated with fertility, so there may be some reduction in bull fertility.

Freemartins behave and grow in a similar way to castrated male cattle (steers).

If suspected, a test can be done to detect the presence of the male Y-chromosomes in some circulating white blood cells of the subject. Genetic testing for the Y-chromosome can be performed within days of birth and can aid in the early identification of a sterile female bovine.

Physical examination of the calf may also reveal differences: many (but not all) freemartins have a short vagina compared with that of a fertile heifer."

[Becky Narramore]

I have just had this happen with my female dauchund. One sac a bot and girl. I am looking for any information. Do I get genetic testing done?