Cyanide poisoning in cattle from Dysphania glomulifera (red crumbweed): using the internet for rapid plant identification and diagnostic advice

Abstract

A 300-strong Angus-Brahman cattle herd near Springsure, central Queensland, was being fed Acacia shirleyi (lancewood) browse during drought and crossed a 5-hectare, previously burnt area with an almost pure growth of Dysphania glomulifera subspecies glomulifera (red crumbweed) on their way to drinking water. Forty cows died of cyanide poisoning over 2 days before further access to the plant was prevented. A digital image of a plant specimen made on a flat-bed scanner and transmitted by email was used to identify D glomulifera. Specific advice on the plant's poisonous properties and management of the case was then provided by email within 2 hours of an initial telephone call by the field veterinarian to the laboratory some 600 km away. The conventional method using physical transport of a pressed dried plant specimen to confirm the identification took 5 days. D glomulifera was identified in the rumen of one of two cows necropsied. The cyanogenic potential of D glomulifera measured 4 days after collection from the site of cattle deaths was 18,600 mg HCN/kg in dry matter. The lethal dose of D glomulifera for a 420 kg cow was estimated as 150 to 190 g wet weight. The plant also contained 4.8% KNO3 equivalent in dry matter, but nitrate-nitrite poisoning was not involved in the deaths.

Neurological diseases of ruminant livestock in Australia. II: toxic disorders and nutritional deficiencies

“…(native couch), 2,3,5 Eremophila sp. (native fuschia) 2,3,5 and Dysphania glomulifera (red crumbweed) 20 in tropical Australia and Eucalyptus cladocalyx (sugar gum) 21 in New South Wales and Victoria, may also cause cyanide poisoning.…”

Alpaca plant poisonings: nitrate–nitrite and possible cyanide

“…Assuming a body weight of 70 kg for the alpacas, 1 the amounts of plant that they ate are estimated as delivering approximately 2 and 4 mg HCN/kg body weight from the 100‐ and 200‐g doses eaten, respectively. The minimum lethal dose of cyanide for ruminants is estimated to range from 2.0 to 2.4 mg/kg 3 . This calculation, together with the rapid deaths, suggested a possible diagnosis of cyanide poisoning in this case.…”

“…Confirming that affected animals had access to known sources of these toxicants, established by assay of samples collected from the site as close as possible to the time of an incident, is essential to diagnosis 5 . This is particularly important for HCN poisoning, because detecting HCN in animal tissues or fluids is problematic because it is so volatile 3 . Detecting increased concentrations of NO 3 in serum or ocular fluids helps confirm nitrate–nitrite poisoning 5 .…”

“…A sample of oaten hay from the bale fed on 12 August was assayed for nitrate and cyanide potential. The assay methods have been described previously 3,4 . The lower limits of detection for NO 3 , nitrite and HCN were 10, 5 and 1 mg/L, respectively.…”

“…After telephone consultation with the senior author (RA McKenzie) on 26 July, the owner delivered to the laboratory a sample of the flowering plant eaten by the alpacas, eye fluid (a mixture of aqueous and vitreous humours) and skeletal muscle samples taken from the second alpaca some 20 h after death. Assays for HCN in the tissues and for cyanide potential and NO 3 in the plant were done immediately by previous described methods 3,4 . HCN was not detected in either the eye fluid or muscle.…”