Fluquinconazole (Jockey® Bayer for example) is a fungicide registered for use on cereal and canola seed.. Poisoning with such a product in livestock can result in clinical signs such as ataxia, weakness, and death, however reports of clinical cases from toxicity are difficult to find and therefore it is assumed that it is a rare occurrence.
A producer in the Moree watercourse area was grazing a herd of Hereford cows with calves at foot on a large open paddock of wheat stubble. The wheat was part of a failed crop and was therefore only partly harvested leaving significant amounts of grain in some areas. The producer noticed several cows recumbent and others appearing uncoordinated, aggressive, and in some cases weak. A shed containing some canola seed grain and an open tub of atrazine amongst other unidentifiable products had been knocked over and there was evidence of grazing of the canola by stock. The canola seed had a distinctive red colour indicating it had been treated with a chemical. The owner was unsure of the chemical used on the grain.
A paddock examination was carried out on several affected animals and an autopsy performed on one animal that was recumbent and appeared moribund.
Animals that were affected but standing showed signs of muscle tremors, head shaking, ataxia, weakness, knuckling, falling, apprehension and aggression. The owner of the stock commented that animals had improved overnight in that most were able to stand up when the previous evening they were recumbent. Some cattle affected also had watery scours.
One cow had already died and another was recumbent and moribund. This cow was examined and found to have a normal rectal temperature and elevated heart rate. There were no other abnormalities noted. This cow was euthanased with a captive bolt pistol and an autopsy was conducted.
Autopsy revealed a mild liver enlargement and there was significant canola seed in the rumen. A full set of samples was taken for histopathology as well as fresh rumen contents, fat samples, brain and spinal cord for TSE exclusion, and a sample of the canola grain from the shed.
Laboratory results excluded TSE, lead poisoning, and rumenal acidosis. There was a mild hepatitis and rumenitis. The hepatitis was consistent with a bacterial shower however the rumenitis was not consistent with acidosis from grain overload.
Rumen contents and fat samples were forwarded for chemical residue testing and very high levels of fluquinconazole (100mg/kg) were found in the rumen contents. Fat tissues were not analysed. The level of fluquinconazole detected was close to the LD50 level for rats.
Fluquinconazole is a triazole fungicide used as a seed treatment for canola for the control of blackleg. It is applied at an application rate of 3.34 kg/tonne of seed and there is no harvest WHP required.
The MSDS for fluquinconazole in Jockey® System Seed Fungicide states that the clinical signs of intoxication include gastro-intestinal irritation, possible liver damage,
lethargy, weakness, ataxia, muscle tremors and incontinence. These signs are consistent with those observed in the affected cattle. It should be noted that apart from the cow that died and the cow that was euthanased prior to autopsy, all other cattle affected (approx 5 others observed) recovered uneventfully.
The main differential diagnoses in this case were rumenal acidosis, poisoning by other chemicals used to treat canola seed including fipronil, and other chemicals present, including atrazine. D-Lactate levels were normal in aqueous and there was no atrazine or fipronil detected in the rumen contents. It is therefore concluded that this is a case of fluquinconazole poisoning in cattle.
The Australian MRLs are 0.2 mg/kg for edible offal and 0.5 mg/kg for meat (mammalian)(in the fat). Residues in fat declined with a half-life of < 7 days when on clean-feed. The APVMA site recommends producers do not graze plants grown from treated seed or cut for stock food within 8 weeks of sowing.
References to the LD50 for fluquinconazole in rats suggest that it is 112mg/kg. The MSDS also states "do not feed treated seed to birds or livestock" indicating either toxicity of the product or unknown residue implications. One study of the residue implications indicated that fluquinconazole residues were stable in milk and edible offals for up to 20 months, in liver for 6 months and in fat for 13 months. A trade advice note from the APVMA on the Jockey® product states "as export markets may not have residue tolerances for Jockey (fluquinconazole), an export slaughter interval of 7 weeks is recommended for livestock that have fed on wheat forage and hay grown from Jockey (fluquinconazole) treated seed."
The author would like to acknowledge pathologist Dr Helen Peam from the Elizabeth Macarthur Agricultural Institute for her assistance with this case.