
05/23/2025
Spina Bifida and Other Neural Tube Defects in Rabbit Kits: Detailed Overview
Neural tube defects (NTDs) like spina bifida and anencephaly are rare in rabbits but can occur—and when they do, they often leave us breeders with more questions than answers. In some cases, multiple affected kits may appear in a single litter, making it even more concerning.
Here’s a detailed breakdown of what causes these issues and how to reduce the risk in future litters.
What Are Neural Tube Defects?
Neural tube defects occur when the spinal cord and surrounding structures fail to form or close properly during early embryonic development. This process normally occurs around day 10–12 of gestation in rabbits. Defects can range from mild deformities to severe exposure of the spinal cord (as in spina bifida), often leading to early death or euthanasia.
--------------------------------------------
Specific Examples:
• Spina Bifida:
This defect, also known as myelomeningocele, involves an incomplete closure of the spinal column, leaving the spinal cord exposed. In rabbits, spina bifida can be associated with other congenital defects like harelip, cleft palate, and kyphosis.
• Anencephaly:
This is a severe NTD where the brain and skull are incompletely formed, often resulting in stillbirth or death shortly after birth.
• Meningocele:
This involves a protrusion of the meninges (membranes surrounding the brain and spinal cord) through a defect in the skull or spine.
• Other NTDs:
In rabbits, other less common NTDs can include vertebral anomalies like hemivertebrae, scoliosis, lordosis, and kyphosis.
--------------------------------------------
Known and Suspected Causes:
1. Folic Acid Deficiency
• Folic acid is essential for DNA replication and neural development.
• Deficiency in the mother during early gestation is one of the leading causes of neural tube defects in many species, including rabbits.
• Even subclinical deficiency can have serious consequences.
2. Genetic Predisposition
• Mutations affecting folate metabolism or neural development may be recessively inherited.
• Inbreeding or close linebreeding increases the chance of expressing these hidden traits.
• If kits with NTDs show up more than once in the same breeding line, genetics should be strongly considered.
3. Environmental Toxins or Medications
• Some dewormers, antibiotics, or even mold toxins in old feed can be teratogenic (cause birth defects).
• Exposure during the first 2 weeks of pregnancy is especially risky.
4. Heat Stress and Other Maternal Stressors
Heat or emotional stress during early pregnancy may seem unrelated—but they can have surprising downstream effects:
• Reduced blood flow to the uterus, depriving embryos of oxygen and nutrients.
• Disruption of hormonal balance, interfering with implantation and growth.
• Impaired absorption of key nutrients, including folate.
• Elevated maternal body temperature, which can directly damage delicate neural tissue.
5. Infections
While rare in rabbits, some maternal infections could interfere with embryonic development and contribute to fetal malformation or loss.
Examples of infections and how they may affect development:
While this area is still not as deeply studied in rabbits as in some other species, here's what we do know (or strongly suspect):
-Encephalitozoon cuniculi (E. cuniculi)-
• A microsporidian parasite that can cross the placenta.
• Known to infect fetal tissues and may contribute to brain, kidney, or spinal defects.
• May not cause symptoms in the dam, or she may just show mild neurological signs or increased thirst/urination.
• Can cause resorption, stillbirth, or neurological deformities in kits.
-Toxoplasma gondii-
• Rare in domestic rabbits, but zoonotic and potentially transmitted via contaminated hay, water, or f***s.
• Can cause early embryonic death, fetal resorption, or deformities.
• Risk increases if rabbits are housed outdoors or exposed to cat f***s.
-Listeria monocytogenes-
• Found in spoiled feed or hay, especially silage.
• Can cross the placenta and lead to abortion, fetal malformations, or stillbirth.
• Also dangerous to the doe—can cause sepsis or neurological signs.
-Pasteurella multocida-
• While more known for respiratory disease, systemic infection in does could reduce uterine blood flow or cause indirect harm to developing embryos.
• May not cause NTDs directly but could increase the risk of early pregnancy failure or developmental problems due to fever and inflammation.
--Other Suspect Infections
• Staphylococcus spp. or E. coli from reproductive tract infections could compromise uterine environment, though not typically linked directly to NTDs.
• Myxomatosis and rabbit hemorrhagic disease (RHD): more relevant in areas where wild rabbits or unvaccinated animals are present. These tend to cause miscarriage or fetal death, rather than specific malformations.
How Infections Harm Development
• Disrupting maternal immune balance
• Causing fever or inflammation during critical developmental windows
• Reducing blood flow to embryos
• Interfering with nutrient delivery, especially folate and oxygen
--------------------------------------------
Prevention Tips for Future Litters
Support Maternal Nutrition
• Ensure the doe gets a folate-rich diet starting before breeding and continuing through the first 2 weeks.
• Good sources: dark leafy greens (dandelion, parsley, kale, plantain).
• Consider adding a 400 mcg folic acid supplement weekly if diet is questionable.
• Feed a balanced pellet with fortified B vitamins and quality hay.
Avoid Inbreeding or Closely Related Crosses
• If NTDs show up, avoid repeating the same breeding unless you’re testing for a recessive trait.
• Introducing new genetics can help reduce hidden genetic risks.
Minimize Early Gestation Stress
• Avoid travel, loud noise, or moving cages.
• Provide cool, shaded housing—especially in summer months.
• Use frozen bottles, fans, or ceramic tiles to keep breeders cool.
Avoid Medications and Toxins in Early Pregnancy
• Don’t deworm or use **herbal remedies or tonics** unless absolutely necessary.
• Any medication should wait unless deemed essential or life saving.
• Keep feed fresh and mold-free. Avoiding mycotoxins is really a no brainer but felt the need to stress it.
If You’ve Already Seen This in a Litter
• Track which kits were affected—were they clustered? Did others die early?
• Record the breeding pair for future reference.
• Cull affected kits humanely, and consider culling breeding pairs from programs if repeated issues occur.
--------------------------------------------
**Here’s a list of herbs to avoid or use with caution during early pregnancy, particularly due to risks of teratogenicity (birth defects), uterine stimulation, or nutrient depletion:
Herbs to Avoid in Early Rabbit Pregnancy
1. Strong Uterine Stimulants
These can cause contractions, interfere with implantation, or disrupt early fetal development:
• Pennyroyal (Mentha pulegium)
• Black cohosh (Actaea racemosa)
• Blue cohosh (Caulophyllum thalictroides)
• Mugwort (Artemisia vulgaris) – also mildly neurotoxic
• Tansy (Tanacetum vulgare)
• D**g quai (Angelica sinensis) – uterine tonic
• Rue (Ruta graveolens) – potent emmenagogue and toxic in high doses
2. Herbs with Known Teratogenic or Hormonal Effects
These may affect fetal development even without causing contractions:
• Wormwood (Artemisia absinthium) – contains thujone, potentially neurotoxic
• Thuja (Thuja occidentalis) – contains thujone; abortifacient
• Comfrey (Symphytum spp.) – pyrrolizidine alkaloids may affect fetal liver/cell division
• Sage (in excess) – high doses may affect hormones and uterine tone
3. Detox or “Cleansing” Herbs
These can stress the liver/kidneys or flush nutrients needed during gestation:
• Dandelion root (strong doses) – gentle in leaves, but root is more detoxifying
• Burdock root – diuretic and detoxifying; best avoided in early pregnancy
• Red clover (large amounts) – mild estrogenic effects; small forage amounts usually safe, but caution with concentrated use.
Safer Herbs to Support Pregnancy (In Moderation)
These are generally considered gentle and nutritive if used in modest amounts:
• Oat straw – calming, mineral-rich
• Nettle leaf – high in minerals and folate
• Chamomile – mild sedative, anti-inflammatory (small doses only)
• Plantain (broadleaf) – nutritive and folate-rich
• Alfalfa – high in calcium, protein, and B vitamins (watch calcium if overused)
Tip:
Even safe herbs should be given in moderation during early gestation, especially in concentrated or dried forms. It's always safest to stick to fresh forage-style amounts rather than strong infusions or tinctures during the first 2 weeks.
--------------------------------------------
Neural tube defects are heartbreaking—but with careful breeding, attention to nutrition, and awareness of stressors, we can reduce the risk in future generations. Sharing experiences and knowledge helps strengthen responsible breeding practices for everyone.
Feel free to share or copy this post for your rabbit communities. I've included as much information as I could. I keep adding tidbits, wanting to cover all my bases. If you feel I've overlooked something or you'd like me to detail any aspect further, please let me know.