Alsike clover toxicity in horses

Alsike clover is a poisonous plant found in meadows and pastures – which can cause liver damage and photosensitivity in horses.

Symptoms of alsike clover poisoning in horses

It’s not known exactly what in alsike clover causes the toxic reaction, but it’s suspected that mycotoxin plays a part.

Horses that digest large amounts of alsike clover are at risk of:

Photosensitivity
This means your horse will have increased sensitivity to the sun’s UV rays, which can result in skin damage resembling sunburned skin. White or light-coloured horses are at greater risk of this.
Liver damage
It is unusual for horses to have liver damage, but it can occur if the horse has eaten large amounts of alsike clover. This can cause the liver to cease functioning properly, inhibiting the ability for metabolism to take place – and also from breaking down the poison present in alsike clover.
Reduced liver function can also lead to secondary photosensitivity.

Other symptoms include:

Poor appetite
Depression
Lethargy
Dehydration
Elevated body temperature
Water swelling (edema) in the lower part of the legs
Jaundice
Diarrhoea
Bleeding rash
Ulcers in the oral cavity

Treating liver damage in horses

Supportive therapy is needed to treat liver damage in horses – and the effectiveness of this depends on how extensively the liver has been affected.

While liver damage is often treatable, some cases can be fatal. It is important that you contact a veterinarian if you suspect that your horse is poisoned.

How to deal with alsike clover

In the garden:

Move the horse to pasture clear from alsike clover.
Plow and sow the pasture – and pay attention to regrowth as the alsike clover is a weed that spreads easily and can reappear if not treated properly.

In your horse’s feed:

Check the horse's feed to see if it contains alsike clover. You may need to consult with your feed supplier to see if you should change feed.
Seed mixtures may also contain alsike clover. It’s best to avoid these.

Check out our helpful advice on the different types of horse feed.

How to spot alsike clover

There are many different types of clover and it can be difficult to know which is which.

Alsike clover's flower is similar to white clover, but the key difference is that alsike clover grows higher than standard white clover. If the clover is growing in an upright position, it Is likely to be alsike clover.

Alsike clover flowers are white or red/pink – and the leaves are egg-shaped.

Learn about other problems to look out for, like sycamore and acorn poisoning in horses.

Written by Amanda Andersson, June 2024. Approved by specialist horse veterinarian Annette Graf.