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Biphalia is the condition of having two penises. It is a condition that occurs, rarely, in individuals of various animal species that typically have only one penis--both males and imposex females (females with male secondary sexual characteristics). Also called: Diphallia, diphallus, penile duplication, where the separation is not complete this is called a "bifid" penis.


Diphallus is a problem in commercial cattle, including buffalo, as it can contribute to infertility. It seems to be most commonly reported in Holstein's but this may simply reflect the popularity of this breed in general.

Examples include: Holstein (1971, 2004, 2014), Nelore (2013) -- see bibliography.

The use of in vitro fertilization procedures is thought to increase the chances of this and other congenital deformities.


Biphallia is rare but has been observed on many occasions in dogs.

Examples include: Poodle (1989), German Shepherd (2017) mixed breed dog (2017) -- see bibliography.

Other Animals

Cases have also been recorded in the following species: mouse (1969), sheep (1979), barnacle (Semibalanus balanoides, 2009), donkey (2014). Biphallus also occurs in a wide range of invertebrates.


In known medical history, about 100 human examples of this condition have been recorded--between 1609 and the present day. This condition is extremely rare, occurring in an estimated one in six million births.

Since 2000 there has been an increase in reported cases, but this may represent increases in population and improved reporting rather than an increase in the actual prevalence of the condition.

With careful use of ultrasound, prenatal diagnosis is now possible.

As with animal, abnormalities are often--but not always--also found in the colon, bladder and spine. For this reason biphallia may be the most obvious sign of other problems needing immediate and skilled surgical intervention and should always be carefully investigated.

When a genetic analysis is able to be carried out, abnormalities are often detected. These mutation seem to be complex and polygenic.

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There is only one known familial case with siblings both having the condition, it is not generally known to run in families.


The immediate cause of this condition is the duplication of cloacal tissues in the embryo, often in conjunction with duplication of other organs. This appears to be associated with genetic abnormalities but the ultimate causes remain unclear.

The Role of Pollutants

Tributyltin is an ingredient is paints used on ships to prevent mollusks and other animals attached to hulls. It is know to cause male sexual characteristics in animals such as the purple snail (Plicopurpura pansa) including biphallia. However, pollutants are not know to have a role in the occurrence of this condition in humans and other mammals.

Possession of two penises is normal in a number of species of earwigs.


  • Abu-Seida, A. M., & Torad, F. M. (2014). Diphallia and double scrota in a donkey: a case report. Research Opinions in Animal and Veterinary Sciences, 4(3), 117-119.
  • Bähr, C., & Distl, O. (2004). Case report. Diphallus in a German Holstein calf. DTW. Deutsche tierarztliche Wochenschrift, 111(2), 85-86.
  • Bosu, W. T., & Barker, C. A. (1971). Diphallia in a Holstein bull. The Canadian Veterinary Journal, 12(1), 21.
  • Center, E. M. (1969). Morphology and embryology of duplicitas posterior mice. Teratology, 2(4), 377-388.
  • Dennis, S. M. (1979). Urogenital defects in sheep. The Veterinary record, 105(15), 344-347.
  • Dodat, H., Rosenberg, D., & James-Pangaud, I. (1995). Familial association of penoscrotal transposition and diphallia (double penis) with patella aplasia. Archives de pediatrie: organe officiel de la Societe francaise de pediatrie, 2(3), 241-244.
  • Dominguez Ojeda, D., Rojas Garcia, A. E., Robledo Marenco, M. L., Vivanco, B., & Medina Diaz, I. M. (2014). Exposure to tributyltin chloride induces penis and vas deferens development and increases RXR expression in females of the purple snail (Plicopurpura pansa).
  • Freick, M., Behn, H., Hardt, M., Knobloch, S., Eftekharzadeh, B., Schütz, E., & Brenig, B. (2014). Monozygotic incomplete caudal duplication in a German Holstein calf. Veterinary Record Case Reports, 2(1), e000048.
  • Frolov, A., Tan, Y., Rana, M. W. U. Z., & Martin, J. R. (2018). A Rare Case of Human Diphallia Associated with Hypospadias. Case Reports in Urology, 2018.
  • Hoch, J. M., & Yuen, B. (2009). An individual barnacle, Semibalanus balanoides, with two penises. Journal of Crustacean Biology, 29(1), 135-136.
  • Hollowell Jr, J. G., Witherington, R., Ballagas, A. J., & Burt, J. N. (1977). Embryologic considerations of diphallus and associated anomalies. The Journal of urology, 117(6), 728-732.
  • Johnston, S. D., Bailie, N. C., Hayden, D. W., Johnston, G. R., & Osborne, C. A. (1989). Diphallia in a mixed-breed dog with multiple anomalies. Theriogenology, 31(6), 1253-1260.
  • Kamimura, Y. (2006). Right‐handed penises of the earwig Labidura riparia (Insecta, Dermaptera, Labiduridae): evolutionary relationships between structural and behavioral asymmetries. Journal of Morphology, 267(11), 1381-1389.
  • Karabagli, M., Karan, B., Ugurlu, U., Mutlu, Z., Yildirim, F., Firat, I., ... & Ozturk, S. (2017). Bifid phallus with complete duplication and a separate scrotum in a German shepherd dog: a case report. Veterinarni Medicina, 62(04), 226-230.
  • Karna, P., & Kapur, S. (1994). Diphallus and associated anomalies with balanced autosomal chromosomal translocation. Clinical genetics, 46(2), 209-211.
  • Laube, R., Cook, A., & Winkler, K. (2017). Diphallia in a Mixed-Breed Puppy: Case Report. Journal of the American Animal Hospital Association, 53(5), 281-284.
  • Perumal, P., Srivastava, N., Srivastava, S. K., Chamuah, J. K., & Veeraselvam, M. (2012). Hereditary and Congenital Causes of Infertility in Buffalo (Bubalus Bubalis) Bulls. International journal of Bio-resource and Stress Management, 3(4), 472-480.
  • Rodriguez, C. (1965). Report of a case of diphallus. The Journal of urology, 94(4), 436-438.
  • Torres, A. A. A., Lhamas, C. L., & da Graça Macoris, D. (2013). Macroscopic and microscopic findings in a set of congenital anomalies in two calves produced through in vitro production. Braz J Vet Pathol, 6, 65-68.
  • Tu, Y. A., Su, Y. N., Yang, P. K., & Shih, J. C. (2014). Prenatal diagnosis of true diphallia and associated anomalies. Obstetrics & Gynecology, 124(2), 416-418.


Umesh Chandra Bhatt from Kharghar, Navi Mumbai, India on March 11, 2020:

This seems to be a rare medical condition. Well researched article. Thanks.

Alexander James Guckenberger from Maryland, United States of America on March 12, 2019:

Debra, do you really think that's a possibility? :o

Debra Roberts from Ohio on March 12, 2019:

As an OB RN who has experience in Maternal-Fetal Medicine, I wonder if the increased use of fertility drugs and like procedures had contribute to this increase in the incidence of this anomaly; along with better reporting?

Alexander James Guckenberger from Maryland, United States of America on February 02, 2019:

This doesn't sound too bad, does it?

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