Horses – Acorn and oak leaves toxicity

At this time of year, ingestion of oak leaves and /or acorns can be a problem of varying severity to horses.tree-402953_640

Both leaves and acorns contain tannin, which can be poisonous to horses, however some horses appear more susceptible than others. The taste can be almost addictive with some horses actively seeking out acorns.

Some horses can eat vast quantities with apparently no effects; others ingest only a small amount and can be quite ill. The main signs are gastro-intestinal and in severe cases kidney damage can occur.

Unfortunately in Hampshire and Surrey, one of the most common trees is the oak tree so it is very difficult to avoid them other than not turning out at all.

CHOICES – wacorns-885012_640hat can you do?

1 – You need to be aware it is a risk and if you want to avoid it completely then don’t turn your horse out – this option however can lead to other problems and so is not completely ideal. If nothing else it will incur extra expense (due the extra bedding and hay) and need extra time (for exercise) so that sanity stays put and none of you hit the floor due to over fresh horses. Reducing turnout can help in some cases however the dedicated acorn eaters are unlikely to stop eating as they will just head straight for the trees and start foraging straight away.

2 – Check your horse’s droppings daily by breaking them open and looking for evidence of acorn kernels, which indicate ingestion. Leaves are more problematic to spot. Keep your eyes open for your horse actively foraging under or around the oak trees.oak-275287_640

3 – Fencing the tress off is often not a practical option because of the number and also the distance the branches spread, but this depends on individual circumstances.

4 – Raking up acorns and leaves will help a little but is a never-ending task and how much does it realistically reduce the load for the dedicated acorn eating horse? Particularly if you share fields with other horses, you need the full co-operation of everyone for this to have any impact at all.

5- If the grass gets really poor and there are still a lot of acorns around, then putting hay out can help distract some horses, others however will choose oak over hay and keep eating.

SIGNS TO LOOK pasture-1505793_640OUT FOR

Lethargy, depression, decreased appetite, low grade colic, constipation followed by diarrhoea, blood in the urine, in-coordination, mouth ulcers and hypothermia are the main signs you may see. There is no specific treatment other than dealing with the signs that occur.

This may all sound very dramatic but as owners you all need to be aware of the problem so that you can make an informed decision about how you would like to manage your horse(s). It is not going to stop the vets here turning their horses out, however we are being extra vigilant for any indication of problems so that we can act quickly.


If you have any questions please call us on 01306 868030 and we will gladly help or advise.

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