A lot of the "active" chemicals in plants that have an effect on the horse have developed as a defence mechanism for the plant. For example, the chemical may be toxic against pests and animals that may eat the plant. As a plant cannot move away from a predator then this is their best form of defence.
Many of these chemicals produced by plants can be used in the horse for a number of different reasons. One point to note is that just because these are natural products does not mean that they can not have detrimental effects on the horse. Some plants are toxic and therefore feeding them to the horse can have harmful effects. Toxic plants often work by having a negative effect on the horse's digestive system which prevents them from digesting food correctly and can lead to weight loss and in some cases death. There are also other ways in which plants can have toxic effects to the horse. Prolonged use of the herbal supplements may also cause problems in some cases. It is also important that they are being given in the correct amounts in order to have the desired effects.
Examples of plants that are used in horses there are many claims as to their potential uses, a lot of these are disputed;
- Devil's claw- anti-inflammatory. These effects have been seen in humans and laboratory animals, it has been found to relieve pain from some conditions such as rheumatism. There are a lack of studies looking at this herb in the horse.
- Garlic- respiration (breaks up mucus), gastrointestinal function, anti-bacterial, anti-viral, anti-parasitic and insect repellent effects. There has been found to be a number of chemicals in the garlic that may have beneficial effects. Studies have been done in horses to look at these effects and many have found it to be beneficial. However, as with most supplements, toxicity can be a problem if too much is fed. Effects from this include gastric irritation, decreased sperm production and anaemia.
- Ginger- anti-inflammatory, anti-thrombitic and anti-bacterial. The effects of ginger have been looked at in horses, one study found it to reduce the recovery time after high intensity exercise. In humans ginger has been found to cause gastric ulcers, this has been theorised in horses. However, herbal supplements to relieve gastric ulcers in horses often contain ginger.
- Yucca- anti-inflammatory, anti-oxidant and anti-spasmodic effects. May also be used as a natural wormer. Many equine joint supplements contain yucca. Most of the research with yucca has been carried out in livestock species however such as cows and sheep and how it affects their digestion.
Do any of you have any experience using herbal supplements in horses?
(Some of this information is from Williams and Lamprecht (2008), The Veterinary Journal, some of the rest is my own opinion and things I have learnt whilst at university).