Canine penis

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The penis of a dog

Male canids have a bulbus glandis at the base of their penises.[1][2][3][4] The penis sometimes emerges from the penile sheath during sexual arousal.[5][6] During coitus the bulbus glandis swells up and results in a 'tie' (the male and female dogs being tied together). Muscles in the vagina of the female assist the retention by contracting.[citation needed]

At the time of penetration, the canine penis is not erect, and can only penetrate the female because it includes a narrow bone called the "baculum", a feature of most placental mammals. When the male achieves penetration, he will usually hold the female tighter and thrust deeply. It is during this time that the male's penis expands and it is important that the bulbous gland is far enough inside for the female to be able to trap it. Unlike human sexual intercourse, where the male penis commonly becomes erect before entering the female, canine copulation involves the male first penetrating the female, after which swelling of the penis to erection occurs, which usually happens rapidly.[7]

Male canines are one of the few animals that have a locking bulbus glandis or also known as a "bulb" or "knot", a spherical area of erectile tissue at the base of the penis. During copulation, and only after the male's penis is fully inside the female's vagina, the bulbus glandis becomes engorged with blood.[8] When the female's vagina subsequently contracts, the penis becomes locked inside the female.[9] This is known as "tying" or "knotting". While characteristic of mating in most canids, the copulatory tie has been reported to be absent[10] or very brief (less than one minute)[11] in the African wild dog, possibly due to the abundance of large predators in its environment.[12]

See also[edit]


  1. ^ MobileReference (2009-12-15). The Illustrated Encyclopedia of North American Mammals: A Comprehensive Guide to Mammals of North America. pp. 977–. ISBN 978-1-60501-279-7.
  2. ^ Kim Long (1996). Wolves: A Wildlife Handbook. Big Earth Pub. ISBN 978-1-55566-158-8. Retrieved 10 December 2012.
  3. ^ L. David Mech (16 May 2012). Wolf. Random House Digital, Inc. pp. 172–. ISBN 978-0-307-81913-0. Retrieved 10 December 2012.
  4. ^ Marshall Cavendish Corporation (1 September 2010). Mammal Anatomy: An Illustrated Guide. Marshall Cavendish. pp. 252–. ISBN 978-0-7614-7882-9. Retrieved 10 December 2012.
  5. ^ Denis R. Lane; B. C. Cooper (2003). Veterinary Nursing 3e. Elsevier Health Sciences. pp. 72–. ISBN 978-0-7506-5525-5. Retrieved 28 February 2013.
  6. ^ Michael S. Garvey, D.V.M.; Anne E. Hohenhaus, D.V.M. (10 December 2008). The Veterinarians' Guide to Your Dog's Symptoms. Random House Digital, Inc. pp. 194–. ISBN 978-0-307-49286-9. Retrieved 10 February 2013.
  7. ^ Dan Rice (3 October 2008). The Complete Book of Dog Breeding. Barron's Educational Series. pp. 51–. ISBN 978-0-7641-3887-4. Retrieved 7 February 2013.
  8. ^ "Semen Collection from Dogs". 2002-09-14. Archived from the original on 2012-02-05. Retrieved 2012-01-29.
  9. ^ Bekoff, M.; Diamond, J. (May 1976). "Precopulatory and Copulatory Behavior in Coyotes". Journal of Mammalogy. American Society of Mammalogists. 57 (2): 372–375. JSTOR 1379696.
  10. ^ Kleiman, D. G. (1967). "Some Aspects of Social Behavior in the Canidae". Integrative and Comparative Biology. 7 (2): 365–372. doi:10.1093/icb/7.2.365.
  11. ^ Creel, S. (1998-08-27), "Social organization and effective population size in carnivores", in Caro, T. M. (ed.), Behavioral ecology and conservation biology, Oxford University Press, pp. 246–270, ISBN 978-0-19-510490-5
  12. ^ Kleiman, D. G.; Eisenberg, J. F. (1973). "Comparisons of canid and felid social systems from an evolutionary perspective". Animal Behaviour. 21 (4): 637–659. doi:10.1016/S0003-3472(73)80088-0. PMID 4798194.

Further reading[edit]