Male reproductive tract and orchidectomy
Esther van Praag, Ph.D.
Warning: this file contains pictures that may be distressing for people.
The reproductive organs of the male rabbit are very similar to that of other mammals, except for the additional ability to retract the testis in the abdomen. They are formed during the embryonic phase. They derive from primitive ancestors of the kidney tubules and the ducts, except for the lobules of the testes and the vasa recta. The blood vessels of the kidney will furthermore be used and deviated in order to supply the testes and the scrotal wall with blood.
The reproductive organ of the male rabbit is composed of different structures. One of them are the testes, which is composed of various components:
• Scrotal sacs: they are located in the inguinal area, ventrally to the anus and can be compared to a sac surrounded by skin and composed of muscles or connective tissue. They contain the testes.
• Testes: they are the reproductive gland, which is composed of tubular loops, lobules and a central tubular plexus (vasa recta).
The tubular lobules are lined with cells that develop the sperm, through a process of cell divisions (meiosis) and maturation. The sperm is brought to the tubular plexus (vasa recta). The later structure is furthermore lined with endocrine cells, secreting testosterone.
• epididymis: this is a coiled tube located at the surface of the testes
The testes descent into the scrotum at the age of 2,5-3 months, and castration surgery is usually done at the age of 4 or 5 months. Male rabbits possess a life-long ability to move freely their testis between the scrotum and the abdomen, via the inguinal ring. The response occurs during handling and examination, or during a fight between 2 males. Indeed, entire male rabbits will inevitably fight and attempt to “neuter” the other male by biting in the scrotal region
Castration surgical procedure
The castration of male rabbits is recommended in order to reduce difficult behavior, like the marking of its territory with strong smelling urine, aggressive attitude and mounting of objects or human body parts like feet and arms.
Further medical reasons to favor the castration surgery include:
• chronic difficult to treat orchitis or epididymitis
• neoplasia of the testes, though this is rare in rabbits.
Orchidectomy is done under general anesthesia. It is a surgical procedure that requires sterile surgical instruments and a preparation of the skin, in order to minimize infection.
Various surgical approaches are available for orchidectomy in rabbits, described in books, videos, or scientific articles. The following pictorial orchidectomy has been done according to the exterior extraction of the testis technique.
Video and pictorial castration procedure
The administration of pain medication for at least 24 h. after the surgery is highly recommended. Pain indeed induces hormonal and physiological responses, which slow down the activity of the digestive tract, delay food intake and recovery.
The presence of blood in the urine during 24 to 48 h post-surgery is normal. Sometimes, the scrotum is filled with blood and hemorrhaged. In rare cases, blood is observed to leak through the sutures. Bleeders, small blood vessels that cannot be ligated, cause this bleeding. It is a non-dangerous nuisance that can last a few days. The administration of vitamin K can help accelerate clotting, if the bleeding is still present after a few days.
If the male rabbit was adult and fertile, he should be confined for 7 to 10 days, and kept separated from non-spayed females at least 4 weeks post-surgery. Younger non mature males can be left with the female partner after a week already.
Many thanks to Akira Yamanouchi (Veterinary Exotic Information Network, Japan) for the permission to use their pictures to illustrate this page.
Many thanks also to Zippy, for his collaboration to take pictures.
Gilsanz V, Roe TF, Gibbens DT, Schulz EE, Carlson ME, Gonzalez O, Boechat MI. Effect of sex steroids on peak bone density of growing rabbits. Am J Physiol. 1988; 255(4 Pt 1):E416-21.
Hussein SA, Azab ME, Abdel-Maksoud H. Metabolic changes concerning the effect of castration on some blood constituents in male rabbits. Dtsch Tierarztl Wochenschr. 1999; 106(3):113-8.
Jenkins JR. Surgical sterilization in small mammals. Spay and castration. Veterinary Clin North Am Exot Anim Pract. 2000; 3(3):617-27, v. Review.
Millis DL, Walshaw R. Elective castrationsd and ovariohysterectomies in pet rabbits. J. Am. Anim Hosp. Assoc. 1992: 491-497
Quesenberry KE, Carepenter JW, Quesenberry P. Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery Includes Sugar Gliders and Hedgehogs, Elsevier Health, 2004.
Smith K. Rabbit Health in the 21st Century. A Guide for Bunny Parents, Second Edition http://rabbithealth101.com/
Harcourt-Brown F. Textbook of Rabbit Medicine, UK: Butterworth-Heinemann, 2001, 192 page
Flecknell P , editor. BSAVA Manual of Rabbit Medicine and Surgery, Gloucester, UK: British Small Animal Veterinary Association, 2000.