Herbs contraindicated in pregnant mares

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Herbs for horses are part of a natural diet, but do you know which herbs are not recommended for the pregnant mare or any other pregnant mammal? Here is a list of herbs contraindicated in pregnant mares compiled from various resources that you might find useful.

When it comes to pregnancy, it is important to do some research before giving anything to the future mother. Even if it seems to be as natural and common as a herb can be.

This list is not exhaustive and I am sure I will come across some other herbs!

Plant Name Effects
Aloe Vera (Aloe vera) Uterine stimulant
Angelica (Angelica spp.) Uterine stimulant
Chaste Berry (Vitex agnus-castus) Emmenagogue
Black and Blue Cohosh (Actaea racemosa) Uterine stimulant, abortifacient, hormonal effects
Burdock (Arctium lappa) Uterine stimulant, oxytocic
Chamomile (Matricaria chamomilla or recutita) Possible abortifacient, emmenagogue, uterine stimulant
Cinnamon (Cinnamomum spp.) Uterine stimulant
Cloves (Eugenia caryophyllata) Abortifacient
Comfrey (Symphytum officinale) Teratogenic, mutagenic, fetotoxin
Fennel (Foeniculum officinale) Uterine stimulant
Fenugreek (Trigonella foenum-graecum) Oxytocic, emmenagogue, abortifacient
Garlic (Allium sativum) Large doses can be uterine stimulating, can have emmenagogue effects, will pass in the milk then to the foal, which may upset its fragile digestive system
Ginger (Zingiber officinalis) Be cautious during early pregnancy as it can be uterine stimulant
Ginseng (Panax spp.) May adversely affect the foetus
Goldenseal (Hydrastis canadensis) Uterine stimulant, emmenagogue
Juniper (Juniperius communis) Uterine stimulant
Lavender (Lavendula angustifolia and all other species) Emmenagogue
Mint – all species – (Mentha spp.) Reduces milk flow
Motherwort (Leonurus spp.) Uterine stimulant
Parsley (Petroselinum crispum) Uterine stimulant, emmenagogue
Red clover (Trifolium pretense) Abortifacient, emmenagogue
Raspberry leaves (Rubus idaeus) Uterine stimulant and should be avoided at the beginning of pregnancy, but are all right at the end for birth preparation and in small dose
Rosemary (Rosmarinus officinalis) Uterine stimulant, emmenagogue, abortifacient
Sage (Salvia officinalis) Uterine stimulant, emmenagogue, abortifacient
Thyme (Thymus vulgaris) Emmenagogue
Turmeric (Curcuma longa aromatica) Uterine stimulant, emmenagogue, abortifacient
Vervain (Verbena officinalis) Uterine stimulant
Wormwood and Mugwort (Artemisia absinthum & vulgaris) Uterine stimulant, emmenagogue, abortifacient
Yarrow (Achillea millefolium) Uterine stimulant, emmenagogue, abortifacient

Glossary of terms:

Abortifacient: induces abortion

Emmenagogue: promotes menstrual flow

Oxytocic: promotes birth

Uterine stimulant: produces uterine spasms

Teratogenic: able to disturb the growth and development of an embryo or fetus

Mutagenic: an agent capable of causing mutations

Fetotoxin: a substance or agent that can poison or cause degenerative effects in a developing fetus or embryo


S.G. Wynn, B.J Fougere “Veterinary Herbal Medicine” Mosby Elsevier, 2007

P.O. Mnimh “The Herb Society’s Complete Medicinal Herbal” Dorling kindersley Book, 1993

M Pedersen “Nutritional Herbology” Wendell W. Whitman Co, 2002

2 thoughts on “Herbs contraindicated in pregnant mares”

  1. Help?
    I’ve gone down the rabbit hole of herbs safe in pregnant mares that help with respiratory/allergy/heaves. My mare only gets heaves when immunocompromised with pregnancy. Nearly everything I find Is marked unsafe. I plan To add garlic (only 6-8g) and spirulina to my regimen now, which is milk thistle seed and dandelion I harvest Myself. I cant Find anything else safe. Can you help?
    Her environmental factors have already been controlled.

    1. Hi Shayna, apology for the late response. These herbs are ok with pregnant mares that may help with respiratory issues: marshmallow root and leaf, nettle as you already know, mullein, peppermint, and rosehips to help with her recovery, echinacea to fight viruses. I hope this helps.

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