Rabbits are more and more present in our homes, but some behaviors coming from their status of prey in the wild remain present. Among them, the nervous pregnancy, or pseudopregnancy, is a quite frequent disorder in rabbits, linked to reproduction in this species.
The reproductive cycle in rabbits
Unlike other mammals, such as bitches for example, female rabbits do not have a really defined heat period. They can be considered to be in heat almost permanently, meaning that they are receptive to males and mating throughout most of the year. As with the cat, ovulation is said to be induced: it is during mating that the ovum is released.
Gestation in the rabbit lasts about 1 month with variations according to the breed going from 29 to 35 days. During the first twenty days of gestation, there is no great change in the behavior of the female rabbit and she still accepts mating with the male. However, this has no effect on the ongoing gestation and cannot result in additional fetuses.
The birth of the litter usually takes place in the morning and takes place quickly: in less than 30 minutes, the young are usually all ejected. Occasionally, the litter is not expelled all at once and there is an interval of a few hours between the expulsion of the babies.
The size of the litter depends on the breed, the age of the mother and the season. Smaller breeds usually have 4 to 5 young, while larger breeds may have 8 to 12 young.
The rabbit is a nesting species: the young are born hairless and blind and stay in the nest made by their mother. Feeding takes place between 1 and 2 times a day and is quite rapid.
How does a nervous pregnancy manifest itself?
Nervous pregnancy is a hormonal imbalance also known as pseudopregnancy. This phenomenon is also known in other species such as the dog for example. This problem occurs when the rabbit has ovulated but the egg has not been fertilized by a sperm. It seems to affect mostly young rabbits, which have had only one real gestation.
In this case, the body of the female rabbit and especially her uterus evolve in the same way as if there was a real pregnancy. The pregnancy hormone progesterone is produced, which causes, among other things, all the signs of pregnancy in the rabbit.
On a behavioral level, the rabbit acts as if she is really carrying young: she builds her nest by pulling out the hair on her belly, retrieves hay or straw, etc. Often, she appears more nervous, even aggressive. However, this behavior varies between individuals with some rabbits conscientiously building a nest and rebuilding it if it is destroyed, while others will only carry hay or objects. Others may show attachment to a particular toy or object as in a bitch with a nervous pregnancy.
The udders may also swell and even produce milk: in this case we speak of pseudo-pregnancy.
This nervous pregnancy often appears about ten days after a stimulus that the rabbit assimilates as a mating. Several causes are listed: it can be due to a non-fertilizing mating because the male is sterile (for example a castrated male who has kept a sexual overlapping behavior), because his semen is of poor quality, etc… It can also occur after artificial insemination, which is common in rabbit breeding. Finally, overlapping behavior between females could be a factor in the appearance of coarse nervousness. However, there are cases of female rabbits living alone that also develop a big nerve pregnancy.
How to differentiate a pseudo pregnancy from a real pregnancy?
In the case of a real pregnancy, the maternal behavior with the constitution of the nest appears between 25 and 30 days after the mating whereas it appears around 10 days after the stimulus mimicking the mating in case of a nervous pregnancy. It is therefore easy to tell the difference when the date of mating is known and there has been no other contact with a male afterwards.
How can this behavior be stopped?
The maternal signs that appear in the case of a nervous pregnancy usually disappear spontaneously and quite quickly. Some of them are harmless (excitement,…) but others can be a problem for the rabbit’s health. Indeed, it is common for the rabbit to accumulate a lot of hay and hair in her mouth in order to build the nest. There is therefore a greater risk of swallowing these hairs and thus causing digestive transit problems that can be serious.
It is possible to accelerate the stop of the nervous pregnancy with some rules:
- Regularly remove the hair clusters that the rabbit could form
- Remove also all materials that could be used by the rabbit to build a nest (except for the hay needed for feeding)
- Destroy the rabbit’s nest as soon as it is built, and each time she builds one.
- Do not touch the belly and especially the udders of the rabbit because this can cause a stimulus that leads to milk secretion and makes the phenomenon last.
- Some natural plants such as parsley can stop the milk flow and can therefore be offered in the diet.
In some cases, these measures are not enough and it is necessary to obtain medical treatment from your veterinarian. The treatment is based on molecules that decrease hormonal secretion (progesterone) and/or molecules that prevent milk production.
In case of recurrence of this phenomenon on the same rabbit, it is advised to sterilize the animal, especially since the nervous coarsening is suspected to promote the appearance of certain uterine tumors and mammary cysts.