{"id":27428,"date":"2014-05-05T06:00:56","date_gmt":"2014-05-05T11:00:56","guid":{"rendered":"http:\/\/lafeber.com\/vet\/?p=27428"},"modified":"2024-03-17T13:58:10","modified_gmt":"2024-03-17T18:58:10","slug":"rabbit-reproduction-basics","status":"publish","type":"post","link":"https:\/\/lafeber.com\/vet\/rabbit-reproduction-basics\/","title":{"rendered":"Rabbit Reproduction Basics"},"content":{"rendered":"

Introduction<\/h2>\n

Even in the neutered<\/a> pet, rabbits draw very little distinction between sexual behavior and social behavior (Harriman 1995). Normal actions like territoriality<\/a>, attention-seeking behaviors like honking<\/a> and circling, and nesting behavior such as digging and chewing, are all intimately tied to the instinctive drive to reproduce.<\/p>\n

If you are reading this article as part of the Basic Rabbit Care Teaching Module<\/a>, please go to the sections on male rabbits<\/a>, female rabbits<\/a>, newborn rabbit<\/a>, and rabbit milk<\/a>. Then take the brief quiz<\/a> to test your knowledge.<\/p><\/blockquote>\n

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\u201cBreed like rabbits\u201d<\/h2>\n

The prolific nature of the rabbit has linked them with fertility and the cycle of life and death since ancient times. In fact the idea of the Easter bunny probably arose from the medieval belief that rabbits, as a creator of life, ushered in the dawn (Fig 1) (Mayer 2003).<\/p>\n

\"Rabbits<\/a>

Figure 1<\/strong>. Rabbits have been associated with fertility and the cycle of life since ancient times. Photo credit: Elliott Brown via Flickr Creative Commons. Click image to enlarge<\/em>.<\/p><\/div>\n

One female rabbit can potentially deliver up to 60 young per year. Because of this fecundity, early explorers carried rabbits as a food source and rabbits were even released on remote islands. Unfortunately the absence of predators allowed rabbit populations to rapidly reach pest numbers on some islands like New Zealand (O\u2019Malley 2005).<\/p>\n

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Male rabbits<\/h2>\n

The head and body of the intact, adult, male rabbit is generally more thickset than the doe (Richardson 2000). The penile sheath is cylindrical and the penis can be easily extruded in rabbits over 2 months of age. The scrotal sacs sit craniolateral to the penis (Fig 2). The scrotum is oblong and partially hairless, and the testicles are relatively large with prominent epididymal fat pads (O\u2019Malley 2005).<\/p>\n

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\"Figure<\/a>

Figure 2<\/strong>. The oblong, partially hairless scrotal sacs sit craniolateral to the cylindrical penis. Photo credit: Dr. Matt Rosenbaum. Click image to enlarge<\/em>.<\/p><\/div>\n

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The testicles descend sometime between 10 to 14 weeks of age. The first appearance can vary with the individual, the breed, and environmental temperature. The adult rabbit can retract the testes back up into the abdomen through the open inguinal ring when stressed or to regulate testicular temperature. Testes descend further on hot days and are brought closer to the body on cool days. This phenomenon can be distinguished from a true cryptorchid male by the absence of scrotal sac(s) (O\u2019Malley 2005, Richardson 2000).<\/p>\n

Prior to castration of the male rabbit, elevation of the hindquarters or gentle pressure on the caudal abdomen will cause testicles to fall back into the scrotum. A closed castration technique is preferred to minimize the risk of post-operative inguinal hernia. If an open surgical technique is performed, the large, superficial inguinal ring should be closed.<\/p>\n

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Female rabbits<\/h2>\n

Adult females, particularly medium and large breed<\/a> does, often develop a dewlap<\/a> or fold of skin beneath the chin. Older does tend to be larger than bucks of the same breed (Richardson 2000).<\/p>\n

The ovaries are elongated, and are located relatively caudal in the rabbit. The oviducts are very long and coiled. The duplex uterus consists of two separate uterine horns separated along its length. There is no uterine body. The mesometrium is a site of significant fat storage in the rabbit, proportionally much greater than in other companion animals. The two uterine horns communicate with two cervices, which join to form a common vagina (O\u2019Malley 2005). The rabbit vagina is relatively long and saccular (Vella 2012). The urethra enters the dorsal wall of the vagina; the clitoris sits on the ventral surface. The vulva appears triangular with a slit-like opening<\/a>, and the appearance of this slit is used to distinguish juvenile females from juvenile male rabbits.<\/p>\n

If the urinary bladder is expressed while the rabbit is in dorsal recumbency, the relatively flaccid vagina can potentially fill with urine. To minimize the risk of contamination during ovariohysterectomy, the bladder is expressed after the patient is anesthetized but before the animal is placed on its back (Jenkins 2012). The suspensory ligaments are relatively long, making exteriorization of the uterus relatively easy, however the large amount of fat in the broad ligament still makes rabbit spays relatively challenging procedures, even in young does. The double cervices are not routinely removed during ovariohysterectomy, however removal is indicated for patients with cervicitis, neoplasia, or endometriosis (Jenkins 2012, O\u2019Malley 2005).<\/p>\n

The female rabbit is an induced ovulator. There is no regular estrous cycle, instead ovulation occurs after mating. If coitus does not occur, the doe will vary in receptivity as ovarian follicles regress and new follicles mature. Periods of receptivity last anywhere from 5 to 14 days and are followed by one to two days in which the doe will refuse to mate. This cycle repeats until conception occurs, although ovarian activity decreases as photoperiod decreases during the late summer to winter months (Vella 2012, Klaphake 2012, O\u2019Malley 2005).<\/p>\n

Vaginal smear cytology is not useful for identification of doe receptivity (O\u2019Malley 2005), however the appearance of the vulva can provide a helpful clue. When the doe is receptive, the vulva is more swollen and is often a pink-purple or reddish-purple color (Klaphake 2012, O\u2019Malley 2005). During anestrus the vulva appears narrow and pale (O\u2019Malley 2005).<\/p>\n

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Breeding rabbits<\/h2>\n

Both male and female rabbits can be quite territorial, and mating is best accomplished if the doe is placed in the buck\u2019s enclosure or if the pair are introduced in neutral territory (Bays 2006, Richardson 2000).<\/p>\n

Upon introduction, the buck follows the doe around, softly humming while sniffing and licking her for approximately 30 seconds (Vella 2012, Bays 2006). He may also spray the female with urine (Bays 2006). The receptive female will hop around in circles or flatten to the floor (Bays 2006). Lordosis is observed when pressure is applied to her back (Bays 2006), while the non-receptive doe will run away from the buck, and if cornered she may vocalize or even bite. Active mating begins when the buck grasps the female by the nape with his teeth. He then mounts the female rabbit, thrusting vigorously until ejaculation occurs relatively quickly. Afterwards the male emits a sharp cry or squeak, before falling onto his back or side while the doe either runs away or begins to bite and kick the male (Video 1)(Bays 2006, Richardson 2000).<\/p>\n