Common Alder
Alnus glutinosa
Horse
Low
Remove access and monitor the horse; call at the first sign. Exclusive or massive consumption of young spring leaves.
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- No specific antidote. Symptomatic and supportive treatment.
- Time to signs
- A few hours to 1-2 days.
- Prognosis
- Excellent. Severe cases are extremely rare.
- Remove access to the tree.
- Provide good quality hay ad libitum.
- Offer clear water ad libitum.
- Contact the veterinarian if marked constipation occurs.
Its ID card
- Height
- 10 m – 30 m
- Flowering
- March to May.
- Toxic parts
- Leaves (especially young ones) and bark.
- Toxin
- Tannins (Tannic acid, gallic acid)
- Habitat
- Riverbanks, streams, marshy areas, very wet woods.
- Soil indicator
- Water-saturated soils, floodplains, riverbanks.
- Regions
- Entire Europe
- In hay
- Not reported
- Palatability
- Rather palatable in spring (tender leaves); some horses readily eat them as a hedgerow treat.
When the risk rises
April-May (young leaves are highly concentrated).
Spotting it in the field
Hazel (also has round leaves, but they are pointed at the tip, not truncated). — smell : slightly acrid smell when leaves are crushed.
- Water-loving tree.
- Dark, cracked bark.
- Round leaves, 'truncated' at the apex (appearing cut off).
- Slightly sticky (glutinous) leaves in spring.
- Fruits are small, woody brown cones (strobiles).
Signs to watch for
Acute toxicity from massive ingestion, potentially chronic if small quantities are ingested repeatedly.
Dose : Not determined for horses, but significant consumption of young leaves is required to cause issues.
- Constipation followed by blackish diarrhea
- Dull colic (mild abdominal pain)
- Dark urine (elimination of tannins)
- Transient decrease in appetite
Who is affected
Other species : Similar digestive disturbances in cattle in case of excess.
In pregnant mares : none.
Getting rid of it
Method : Eradication is generally not necessary as the tree plays an important ecological role. Management focuses on limiting access and consumption.
- Avoid overgrazing of riverbanks in spring.
- Ensure sufficient supply of quality hay, especially during the young growth period.
- Identify and fence off high-risk areas if necessary.
Frequently asked questions
Can Equio identify Common Alder from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Common Alder dangerous in hay?
Hay risk is not always reported for this entry, but suspicious forage should still be isolated until checked.
This page is informational. If ingestion is likely, if signs appear, or if the horse is fragile, contact a veterinarian immediately.