Now that spring is here as I drive around on my rounds I can not help but notice several plants that may be toxic to grazing animals such as horses and ruminants growing along the roadside. I thought this month I would write a brief and by no means comprehensive article on common poisonous plants we see animals affected.

Fireweed (Senecio madagascariensis):

A common weed on the central coast, Fire weed contains pyrrolizidine alkaloids which cause irreversible liver damage in ruminants and horses. Young or hungry animals are more likely to eat the plant.

Refer to NSW Department of Primary Industries website for further information:

Bracken Fern (Pteridium esculentum):

Bracken fern can cause Vitamin B1 deficiency in horses and pigs. It also is one cause of redwater’ or red coloured urine, and prolonged consumption in ruminants can lead to
cancer of the bone marrow and bladder.

Crofton weed (Ageratina adenophora):Refer to NSW Department of Primary Industries website for further information:

A common weed of roadsides, Crofton weed is toxic to horses. It causes irreversible damage to their lungs.

Refer to NSW Department of Primary Industries website for further information:

Lantana (Lantana camara):

Lantana most commonly causes liver damage and may also cause photosensitisation (increased sensitivity of the skin to sunlight, often noted as blistering to the hairless skin on ruminants)

Refer to NSW Department of Primary Industries website for further information:

Privet (Ligustrum sp):

Privets are commonly grown as garden ornamental trees in Australia. They are known to be toxic to horses and cause symptoms such as colic, diarrhoea, nasal discharge, in-coordination and possible lung and heart problems. They are also potentially toxic to other species.

Wild tobacco (Solanum mauritianum):Refer to NSW Department of Primary Industries website for further information:

May cause gastrointestinal upset. to Qld Department of Agriculture and Fisheries for information


The good news is many of these plants cause symptoms only with prolonged grazing, so if the plant is removed from your property your animals are unlikely to develop symptoms. If your animals show any symptoms that you suspect may relate to the toxicity of these plants contact your vet and arrange a consultation so they may discuss further diagnostics to determine the cause of your animals ill health.