I have recently been encountering more and more horses that have problems that appear to be associated with a lack of boron in their diet. This is especially relevant in unshod animals, as well as older animals or those suffering from laminitis.

Soil analysis has confirmed the low levels of this nutrient.

The role of boron in humans and animals has long been known to be diverse. An animal’s inability to access boron from their diet will:

  1. Reduce the horse’s ability to reduce inflammation – horses with laminitis will be especially prone to an inability to reduce inflammation.
  2. Swollen joints will subside very slowly. This is associated with the animal’s inability to synthesise lipoxygenase – an enzyme that helps control inflammation.
  3. General movement will be restricted due to the collective effect of the inflammation.
  4. Old and young animals will display an inability to maintain bone density and be slow to recover from injury.
  5. Sensitive feet, or poor hoof health, is often a problem associated with a lack of boron. This will obviously be exacerbated if the horse is suffering from laminitis.
  6. Boron and magnesium are both required to enable a horse to metabolise calcium. Without adequate access to both elements bone loss will steadily accelerate, which often stimulates the development of osteoporosis.
  7. If your horse is lacking ‘mental alertness’ and underperforming, then a lack of boron can often be the problem.

Boron often combines with the hydroxyl groups and form corticosteroids, which are known to alleviate symptoms associated with rheumatoid arthritis and joint inflammation.

Boron is rapidly absorbed and then excreted in the urine, so its potential for toxicity is minimal. Feeding a proprietary supplement rarely causes a problem, but if your horse has a known kidney problem, then boron intake should be carefully monitored as impaired kidney function could reduce excretion resulting in boron accumulation.

Boron supply

Boron naturally exists in the soil organic matter and micro-organism residue. So, creating a soil that has plenty of organic matter and a good structure to allow air and water to enter the soil and break down the residue is important for liberating boron for the grass to utilise.

Aerate the soil twice yearly with a chain-harrow or similar. Needless to say, the grassland needs to be firm and dry enough to travel on without damaging the sward. This activity will always be the most cost-effective sward management strategy ever undertaken as it removes some of the dead thatch and allows air back into the topsoil.

The other benefit of the harrow tines scratching the soil surface is that a chemical reaction occurs resulting in a small quantity of nitrogen being extracted from the atmosphere and placed directly into the root zone stimulating grass growth.

A healthy plant with a correspondingly high calcium content (calcium is an essential constituent of all plant cells, and therefore growth) will require more boron to generate a nutritious plant. This is especially important with hay or haylage production as the taller plant, compared to grazing grass, will inevitably have a higher calcium content and requirement for growth.

Care should be taken to consider the potassium content of the soil. If levels are high (which will generate hyperactive horses) then this will exacerbate the negative effect of a low soil boron level and promote symptoms indicated in 1-7 above.

Boron has a negative charge, which means that it is easily leached out of the soil during periods of high rainfall. Therefore, even if your soil has an adequate supply, heavy rain may mean that a supplement is still required to ensure horse health.


Boron is equally as important as calcium and vitamin D as one of the essential minerals involved in horse bone and joint health. Boron can reduce inflammation, increase mental alertness and is often overlooked as it has positive effects on many aspects of health.

Find out what is happening in your soil and what your horse’s behaviour is telling you.


Let Lordington Park Agronomy help you generate happy horses.