Reproductive Disorders in Rabbits

 by Lisa Iverson, DVM 

Since we ail have rabbit breeding in common, I thought I would write my first article about breeding rabbits and some of the problems that can occur.

Unique things that are normal for rabbits

Rabbits are induced ovulators, which means that a doe does not release her eggs from the ovaries unless a buck stimulates her during copulation. The doe's heat cycle is 16-18 days long, with about 12 fertile days. Average rabbit gestation is 30-33 days but can be as short as 29 days or as long as 35 days. A few days to a few hours before giving birth, the doe builds a nest of hay or straw and from hair that she pulls from her own body. Nest building behavior starts with: digging, at about 6-8 days prior to kindling; then nest building, 1-3 days before kindling; and finally hair pulling 24 hours to minutes before giving birth. Kindling usually occurs in the early morning hours and only takes about 30 minutes from start to finish. Rarely are the young born several hours apart. Anterior (head first) and posterior (hind quarters first) presentations are both normal.

Pseudopregnancy

If ovulation does not result in pregnancy, the doe will have a pseudopregnancy, or false pregnancy. This may be due to a sterile mating with a buck or by being mounted by another doe. Occasionally a doe that lives alone will learn to stimulate herself to ovulate, resulting in recurrent pseudopregnancies. This can be a problem for the breeder. Pseudopregnancy usually lasts 16-18 days, during which time the doe is unable to conceive. A doe goes through all the hormonal changes of pregnancy during a false pregnancy in a shorter period. At the end of a false pregnancy, the doe usually builds a nest and may even lactate. Fertility usually then returns to normal.

Pregnancy toxemia (ketosis)

Pregnancy toxemia is very complex, and although it is fairly common, very little is known. This will serve as an overview. Perhaps, if there is interest, another article will be devoted to pregnancy toxemia. Signs vary from lack of appetite, weakness, and depression, to abortion to sudden death. Does are usually affected during nest building, but pseudopregnant does and does that have recently given birth may also be affected. The liver becomes enlarged and infiltrated with fat cells (a condition known as hepatic lipidosis). This fat interferes with the normal metabolic processes of the liver, leading to an accumulation of toxins in the blood. Obese does and does with an obstruction in the stomach (such as a hairball from building a nest) are at greatest risk. The goal of treatment is to get the doe to eat, even if that means force-feeding. Some people also recommend treating with a steroid anti-inflammatory; these are available only through a veterinarian. Because most does do not survive severe toxemia, the best treatment is prevention: do not allow your does to become obese, and do not increase carbohydrates in the diet at the end of pregnancy.

Dystocia

Dystocia, or difficult labor, is not very common in rabbits. Predisposing factors include obesity, large kits, and a narrow pelvic canal. Since we breed for a large round head in Holland lops, dystocia may be more common in our breed than in many others. Signs of dystocia are straining and bloody or greenish vaginal discharge. Oxytocin and calcium gluconate can be given to strengthen uterine contractions. There is a risk of uterine rupture if oxytocin is given before both cervices are dilated. If the doe does not deliver her kit within 30-60 minutes of this treatment, a Cesarean section should be considered.

References:

Mannin & Pingler, and Newcomer (ed.), The Biology of the Laboratory Rabbit, Second Edition, Academic Press, 1994
McNitt, Patton, Lukefahr, and Cheeke, Rabbit Production, Eighth Edition, Interstate Publishers, Inc., 2000
Okerman, Diseases of Domestic Rabbits, Second Edition, Blackwell Science, 1998
Richardson, Rabbits Health, Husbandry, & Diseases, Blackwell Science, 2000
Hillyer and Quesenberry, Ferrets, Rabbits, and Rodents Clinical Medicine and Surgery, W.B. Saunders Co., 1997


The Hollander / Summer Issue - 2001