Bathurst bur
Xanthium spinosum
Other names
prickly burweed, spiny clotbur, spiny cocklebur
Description
Up to 1m tall bush (depending on situation). Stems with thick yellow sap. Leaves little or no petiole, but with thorns in axilla. Leaves pinnate, usually divided in 3. Flowers inconspicuous. Fruit (bur) oval and covered in hooks with two seeds inside.
Similar plants
Noogoora bur, X. strumarium is similar but has no thorns.
Distribution
Locally common in waste ground in the N Island, occasionally found in Nelson, Marlborough, Canterbury and Southland.
Toxin
Carboxyatractyloside, a kaurene glycoside. This is mainly found in the bur (not eaten) and the seedlings with cotyledons, which are palatable. When the seedling grows true leaves, the toxin is present in such small amounts that poisoning is unlikely.In S. Africa, the burs have also caused problems in wool.
Species affected
All animals potentially. Poisoning recorded in pigs and cattle overseas but not in NZ.
Clinical signs acute
Depression, nausea (vomiting), renal failure, lack of coordination, spastic gaits, hyperexcitability, blindness, coma, and death. Allergic dermatitis in people.
Clinical signs chronic
Post mortem signs
Diagnosis
History, raised liver enzymes.
Differential diagnosis
Treatment
Activated charcoal.
Prognosis
Prevention
References
Hatch RC, Jain AV, Weiss R, Clark JD. Toxicologic study of carboxyatractyloside (active principle in cocklebur--Xanthium strumarium) in rats treated with enzyme inducers and inhibitors and glutathione precursor and depletor. Am J Vet Res. 1982 Jan;43(1):111-6.
Witte ST, et al., Cocklebur toxicosis in cattle associated with the consumption of mature Xanthium strumarium, Journal of Veterinary Diagnostic Investigation 1990 Oct; 2(4): 263-7
Stuart BP, et al., Cocklebur (Xanthium strumarium) intoxication in swine: review and redefinition of the toxic principle, Veterinary Pathology 1981; 18(3): 368-83
Krejci ME and Koechel DA, Acute effects of carboxyatractyloside and stevioside, inhibitors of mitochondrial ADP/ATP translocation, on renal function and ultrastructure in pentobarbital-anesthetized dogs, Toxicology 1992, 72, 299-313
Martin, T. M., Stair, E. L., Dawson, L. 1986. Cocklebur poisoning in cattle. J. Am. Vet. Med. Assoc., 189: 562-563