Sweet Clover (Common Yellow Sweet Clover / White Sweet Clover)
Melilotus officinalis / Melilotus albus
Horse
Severe
Any suspected ingestion is an immediate veterinary emergency. Exclusive or majority consumption of poorly dried (moldy) sweet clover hay over several weeks.
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- Vitamin K1 (antidote), potentially blood transfusion
- Time to signs
- Several days to several weeks of exposure
- Prognosis
- Grave if internal hemorrhages have begun. Good if detected early and treated with Vitamin K.
- Immediately stop feeding the suspect hay.
- Contact an emergency veterinarian.
- Prepare the horse for transport if necessary.
- Monitor for signs of hemorrhage.
Its ID card
- Height
- 0.3 m – 1.5 m
- Flowering
- June to September
- Toxic parts
- The entire plant, ONLY when poorly preserved as hay or silage (moldy).
- Toxin
- Dicoumarol (Vitamin K antagonist, only if the plant is moldy).
- Habitat
- Roadsides, wastelands, chalky embankments, sometimes sown as green manure or forage.
- Soil indicator
- Dry, chalky, stony soils, embankments.
- Regions
- Entire Europe, North America
- In hay
- Yes — stays toxic once dried
- Palatability
- Very good. It is an excellent forage plant when fresh; horses love it and consume it without danger as long as it is fresh.
When the risk rises
All year round (via poorly stored winter hay).
Spotting it in the field
Alfalfa (purple flowers, no coumarin smell). — smell : strong smell of freshly cut hay or vanilla when crushed.
- Tall, branched herbaceous plant (up to 1.5 m).
- Trifoliate leaves (similar to alfalfa).
- Long racemes of small yellow (officinal) or white (albus) flowers.
- Very strong smell of vanilla/cut hay when crushed.
Signs to watch for
Chronic (cumulative) toxicity
Dose : The exact quantity depends on the degree of mold and duration of exposure, but significant consumption of moldy hay over several days can be sufficient.
- Spontaneous nosebleeds (epistaxis)
- Blood in urine and feces
- Large hematomas under the skin from minor bumps
- Very pale mucous membranes (severe anemia)
- Extreme weakness, very rapid heart rate
Who is affected
Other species : Very frequent fatal hemorrhages in cattle ('sweet clover disease').
In pregnant mares : almost certain abortion due to placental hemorrhage.
Getting rid of it
Method : Pull the plant before flowering, wearing gloves. Destroy uprooted parts by burning or deep burial to prevent seed dispersal.
- Ensure hay is perfectly dry before storage.
- Avoid feeding hay showing signs of mold.
- Identify and remove sweet clover from hayfields.
- Do not use sweet clover silage.
Frequently asked questions
Can Equio identify Sweet Clover (Common Yellow Sweet Clover / White Sweet Clover) from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Sweet Clover (Common Yellow Sweet Clover / White Sweet Clover) dangerous in hay?
This entry flags hay vigilance. Isolate suspicious forage and ask for professional advice if exposure is possible.
This page is informational. If ingestion is likely, if signs appear, or if the horse is fragile, contact a veterinarian immediately.