06/19/2023
BUTTERCUPS
Many horse owners ask about blisters, sores and scabs that they see on their horse's lips, gums, noses and lower legs at this time of year.
If you have buttercups in your grazing fields, then these might be the reason for those sores (but not exclusively*).
Symptoms include the horse developing blistering in and around the mouth and/or what looks like sunburn on their nose or mud-fever scabs on their lower legs (this is seen a lot in horses with white hair and pink skin, however it is not exclusive to these types).
Buttercups contain a glycoside (a chemical compound found in plants) called 'Ranunculin' which, when the plant is broken down through eating or being disturbed (e.g. when crushed/bruised when trodden on), this compound breaks down to form a toxin called 'Protoanemonin'. It is this toxin which, when coming in to contact with mucous membranes (tongue, gums), lips and skin causes the blisters and sores.
Buttercups are actually very bitter to the taste and given the choice, horses will avoid eating the plant itself, however if ingested it can sometimes cause diarrhoea, excess salivation and colic.
Buttercups are prolific growers and are seen on pastures which have been over-grazed, are horse-sick or the grass is sparse (i.e. areas of bare mud where grass is struggling to grow due to previous damage such as poaching) and can thrive because horses prefer not to eat them so they are avoided and left to grow.
The presence of buttercups often indicates the need for improvements to soil structure and drainage, and harrowing the field during April to October can help to improve grass growth, aerate the soil and break-up the growth of the buttercups. They are very hard to eradicate completely and pasture health and management is key - they seed when they are in flower, so they need to be treated before the flowers appear.
An interesting fact is that Buttercups are 'heliotropic' which means that they follow the sun across the sky throughout the day (like Sunflowers do).
If your horse, pony or donkey shows any of these symptoms mentioned, always contact your vet.
*Note: A sunburnt-looking nose can also be caused by ingestion of St. John's Wort or a sign of liver disease in horses, which can cause photosensitisation (when the animal becomes abnormally reactive to ultraviolet light) which can be caused by ingesting toxic plants, amongst other causes.
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