Many riding platforms are full of one discussion: the question about the right dose of garlic.
According to this experts warn horse owners not to feed an overdose of this herb. Their argument: an overdose can harm the horses´ health.
Garlic as a feed additive for horses?
For a long time horse owners and experts agreed in one point: garlic does not only have positive effects for us humans, but also for horses. If you feed it to horses, flies and other parasites will stay off the horse. A group of scientists in Guelph (Canada) carried out an experiment (published in the professional journal “American Journal of Veterinary Research”: Association of maximum voluntary dietary intakeof freeze-driedgarlic with Heinz body anemia in horses, 2005, 66) and the results did not only cause a great discussion, but also some rumor in the stables.
The experiment
The whole experiment took 71 days and got separated into two periods. In these respective periods the horses got a different dose of garlic: 0,05 g per kilogram bodyweight up to the 41. day and then 0,25 g per kilogram bodyweight until the 71. day. Scientists made blood screenings of the tested horses and compared them with the results of other horses which did not eat any garlic at all.
The result of the experiment: the blood screening of the tested horses showed a degradation of the blood pigments (hemoglobin). This causes a general reduction of the red blood cells (erythrocytes) which is also known as anemia. This indeed is a serious disease with negative effects on the horses’ health.
How do we have to interpret the result?
Undoubtedly at first this result can confuse riders and horse owners. They fed garlic for a 
long time and always just wanted the best for their horse. That is why one needs to interpret the result carefully. In the experiment the horses got a dose of 0,25 g per kilogram bodyweight (41.-71. day). This is a dose which is higher than the recommended dose anyway. Therefore the experiment shows the worst case of what can happen if you feed an overdose of garlic for a long period. According to this the experiment does not represent an everyday life situation but shows the consequences of an overdose feeding. To sum up one can say that the experiment has a warning effect.
Can you feed garlic to horses?
Yes! Nevertheless one needs to follow the same principles as with all other medicinal herbs: the dose makes the poison! The daily dose of garlic is 0,2 g per kilogram bodyweight. If you do not feed more than this dose you can be sure that garlic has positive and healing effects on your horse. You can feed garlic
- as a prevention against flies and other parasites
- as a prevention against allergic reactions (coughing or bronchitis)
- anti-inflammatory: wrap the garlic in a bandage and tie it around the wound
- as a prevention against eczema and laminitis
Summary: Horse owners can go on feeding garlic to their horses. Referring to this it does not make any difference if you feed it as a powder or in form of a fresh garlic clove because horses usually like to eat anyway.
It is important not to feed an overdose!