Ageratina Adenophora

Ageratina Adenophora

Ageratina adenophora, more commonly known as Crofton weed or Mexican devil, is a common poisonous pasture weed found primarily in coastal regions of NSW, southern QLD, and the north island of New Zealand (although there are also reports of growth in Melbourne, Perth, Adelaide, and northern QLD). It is a declared noxious weed in multiple Australian states.

Crofton weed contains a derivative of agerophorone and is highly toxic to horses. Horses are the only animal known to be affected by this plant and will readily graze on it (in some cases even in preference of alternate pasture species). Horses that ingest this plant over a period of months can develop an illness known as Crofton weed poisoning, Numinbah horse sickness or Tallebudgera horse disease.

The plant is considered at its most toxic whilst flowering, however symptoms are not typically seen until months after grazing. Early symptoms include coughing particularly during exercise, and reduced exercise tolerance. As the illness progresses, affected animals may lose weight, develop permanent hardening (fibrosis) of the lung tissue, and die. Those that survive can have irreversible lung damage and a permanent reduced exercise tolerance.

Unfortunately, there is no specific antidote for Crofton weed poisoning however veterinary treatment may allow some affected horses to survive. Restricting access to areas of growth is therefore crucial.

☎ If you are concerned your pet has been exposed to a poisonous plant, please phone the Animal Poisons Helpline on 1300 869 738 (AU)
or 0800 869 738 (NZ) for advice.

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This post has been gratefully sponsored by a grant from Animal Welfare Victoria.