Under attack: how herbs can help the horse’s immune system

In the second part of a series on the horse's immune system, we look at how herbs can help

The immune system plays such an important role in animal health that it should be considered in regard to most conditions, other than acute injury. A strong immune system supports the horse’s ability to resist viruses, internal and external parasites, is called for when treating skin conditions like mud-fever or ringworm and will certainly help both mare and foal in the first month or two after birth.


Of all the thousands of medicinal herbs, echinacea is probably the most researched. It has a history of use over thousands of years by the native Americans and has now spread to be widely used around the world. Echinacea is possibly the world’s most used herb by humans and fortunately much of the research is directly applicable to horses. It is also one of the few herbs that has had research targeted at horses.

Its traditional use has been to boost the immune system and it is widely used to prevent disease as well as in acute upper-respiratory infection.

There are three species of echinacea, also known as purple cone flower, that you may come across. They are Echinacea angustifolia, E. purpurea and E. pallida. The most common is E. purpurea. When you buy it, look for products made from the root.

If you are buying dried herb it is easy to tell. The milled root should be a fawn colour and may contain flecks of purple. As you would expect, the leaf is green. If you are buying a liquid extract, which is preferable to the dried herb, you have to rely on the label. If the manufacturer doesn’t declare which part of the plant is used and the extract strength, I suggest you leave it on the shelf.

Does it work? Yes. Scientific studies on humans and horses confirm its traditional use. But there are a couple of misconceptions that you should be aware of. Firstly, it is safe to use long-term and secondly, its effect does not diminish with time. The people who tell you different are misinformed.

Immune-supporting herbs

Cat’s Clawcats-claw-dreamstime_m_18599683-copy

Cat’s claw (Uncaria tormentosa) is a herb which we have been using more and more. Not only is it immune-enhancing but it is also anti-inflammatory. Clinical studies in humans have shown promising results in the treatment of chronic immune insufficiency, and an immune-enhancing active alkaloid has been isolated from the bark cells.

We often use a combination of herbs and have found that cat’s claw combines very well with echinacea as an immune stimulant. Cat’s claw also combines really well with goldenseal (Hydrastis canadensis) for the treatment of ear infections.

Goldenseal and barberry

Berberis Ilicifolia. Branch of a blossoming barberry . yellow flowers (barberries) on bush. bee on a flower,
Branch of a blossoming barberry

Goldenseal (Hydrastis canadensis) is another herb indigenous to North America. It is often used in conjunction with echinacea and is very effective. Unfortunately, its effectiveness has contributed to it being over-used, abused and used inappropriately. So much was harvested from the wild that it has become endangered. It is now cultivated but is hard and slow to grow. All this has resulted in it becoming very expensive. We use it for very special applications, but for general day-to-day use, barberry (Berberis vulgaris) is an effective alternative. 

Goldenseal and barberry are both bright yellow in colour due to the berberine content. This is an alkaloid that demonstrates significant antimicrobial activity against a wide range of organisms. Berberine also has immune stimulating properties;  preliminary research suggests that it may help to increase immune cell activity, and it is also reported to increase blood supply to the spleen, which may help the immune-supporting activity. 

We use barberry topically in mud-fever, ringworm and other skin conditions. Ideally, it should be applied as an extract to give maximum effect but if this is inconvenient you can easily make it into a cream and apply that to the affected area.


Thuja (Thuja occidentalis) is mainly thought of as an anti-viral herb and while this is true it is also a general immune stimulant. It has been shown to stimulate spleen cell proliferation which is linked to immune system activity, to increase the production of T-cells, and to increase antibody production and white blood cell activity. Several mouse trials have confirmed these actions which, combined with its anti-viral activity, are why it is an integral constituent in our anti-viral formula. 

Anti-allergy herbs

An allergic reaction is a hyper-immune inflammation reaction, so we are looking for herbs to suppress this and reduce the inflammation that goes with it. The effects can take a variety of forms, from a runny nose and watering eyes through sneezing to a full-blown and potentially fatal anaphylactic shock.  

Anaphylactic shock requires immediate, urgent veterinary treatment. However, there are some specialist herbs that can help with allergies; these include three classics: eyebright, albizzia and baical skullcap.

There is also a quick and easy fix that is worth trying first – raw onion. This common vegetable is surprisingly effective in controlling acute but not serious inflammation. This would include, say, the nasal swelling of allergic rhinitis or that associated with a rhinovirus infection. The usual dose is one onion a day. Use the size of onion to match the horse…a big onion for a big horse and a small onion for a small horse. We find the best way to give it is chopped up in a blender with some cider vinegar and mixed in the horse’s feed. If possible, split it between two feeds. Most horses find it palatable, although some owners find the effect of the onion on the horses’s gut to be less than sweet.


Albizia lebbek is an Indian plant, the bark of which has demonstrated anti-allergic and anti-anaphylactic activity by oral administration. These were human studies but the results seem to be consistent with the action we see in horses. Albizia inhibited the sensitisation process, reduced the synthesis of allergy-inducing antibodies and also relieved allergic conjunctivitis.  

Baical Skullcapbaical-skullcap-26111711_l-copy

Scutellaria baicalensis root is a Chinese herb that we use in a Western manner.

It is anti-allergic and anti-inflammatory so is used for treating asthma and allergic dermatitis; studies suggest it may block the common pathway for the release of histamine, which is involved in acute allergic reactions and inflammatory responses.

Eyebright eyebright-123rf-23122675_l-copy

Euphrasia officinalis is a European herb used to treat eye conditions such as irritation and redness, infection, inflammation and conjunctivitis. In this type of condition it can be used topically, perhaps by wiping a tea over the eye, but it is also really useful in nasal catarrh, sinusitis, chronic sneezing and rhinitis.  

It is interesting that these three herbs which go together so well arise from three different systems of herbal medicine. Anyway, we have found them a very useful combination and are glad to have all of them available. Many horses suffer from pollen allergy in the spring and a mix of these in the form of liquid extracts has a quick effect. Unfortunately, although it is an effective mix, it only provides relief and not a cure. Everyone is still looking for that.


We looked before at how stress in the form of excessive exercise, bad weather and a host of other influences can affect the immune system. Herbal medicine is uniquely placed to help. Within the body there are feedback systems that are in a constant state of balancing and rebalancing. When everything is running as it should, this is known as homeostasis. If an individual becomes stressed, this state of homeostasis is lost.  

There is a small group of herbs known as adaptogens that help the body return to and maintain its proper state of balance. These herbs contain substances which improve the body’s ability to handle stress and resist disease. In other words, adaptogens enhance the body’s adaptive response to a wide variety of stressful events.

Probably because they can help with athletic performance, there have been many papers written on adaptogens and lots of plants which have been considered. Many are hard to get and in others the claims are far from proven.  We tend to concentrate on just two which have stood up to rigorous scrutiny and are generally accepted as principal adaptogens. They are Siberian ginseng (Eleuthrococcus senticosus) and schisandra (Schisandra chinensis). 

Siberian Ginseng

Siberian ginseng grows widely in East Asia, China, Russia and Japan.  The Russians have researched this plant widely and it has been used successfully in their space programme. It increases mental alertness, work output and athletic performance, but there have been some trials which also show that it had no effect on three measures of performance (cardiorespiratory fitness, fat metabolism and endurance performance) but did improve general health and reduce absenteeism in the workplace. Clearly a bit more work is needed here, but our own clinical experience with this herb has been very positive.  


Schisandra on the other hand has the benefit of a couple of studies on horses. These only relate to its ability to improve performance, but there are plenty of human studies to support its use as a proper adaptogen. In both studies the horses were given a single dose or a placebo 30 minutes prior to exercise. The treated horses showed reduced heart and breathing rates and faster track times than the control group. In the older trial, this amounted to 1.8 seconds over 800 metres. We’ve also had consistent feedback that endurance horses regularly given schisandra show quicker recovery and lower rejection rates at vet checks during competition. Schisandra is also a valuable liver herb and through stimulating liver activity it assists in reducing lactic acid levels.

So, adaptogens are an important and useful (though slightly roundabout) way to support your horse’s immune system. By moderating the stress response, they support optimal immune function and so aid in resistance to infection and recovery following illness or injury.

As we have seen over this two-part article, the immune system is often overlooked and forgotten but its function is vital to the continued good health of your horse. If you feel that he is unwell too often or has other unresolved issues, the effects of a course of echinacea might surprise you.

  • This article was first published in the May 2014 issue of NZ Horse & Pony