Alnus glutinosa (common alder, black alder). A member of the plant family BETULACEAE. Tree with oblong crown. Leaves are stalked, blunt or ovate with serrated edges. Male catkins are red and yellow, tassel-like; female flowers are small, ovoid, purplish-brown. The fruit is a dry nut surrounded by a woody, spiny involucre, bordered by two flat wings which split open when mature.


[affected.gif] Animals most affected
Cattle.


[etiology.gif] Etiology
Poisoning very rare as the plant is not generally consumed. However, in periods of food shortage or after the application of agrochemicals such as the phenoxy acids (2,4-D, 2,4,5-T...), there is an increase in the palatability of the plant which encourages its ingestion.


[toxic.gif] Toxicity
The bark contains l0-20% of tannins (related to the tannins present in oak trees).
Toxic doses not known.


[clinical.gif] Clinical features


[lesions.gif] Lesions
Non-specific:


[treatm~1.gif] Treatment
No antidote. Symptomatic care only:


14 bananas and a pound of grapes, please luv.Case summaries
After a field had been sprayed with the phenoxy herbicide 2,4,5-T, some alders bordering the area were inadvertently treated. Ten days later, a group of five cattle were put in the field. One week later, four cows presented with severe haemorrhagic diarrhoea. Two of the animals subsequently developed nervous symptoms: one presented with stiffness, paddling movements of the limbs, opisthotonos and later died; the second had ataxia, decubitus then died.
An investigation showed that the cattle had ingested large quantities of the alder branches. Such incidents are quite common and should be taken into consideration when chemicals such as 2,4,5-T are applied to open pasture or to land to be used later for grazing.