Suspected alimentary poisoning by aluminium phosphide in horses – a case report

In November 2018, a horse owner from the Czech Republic experienced the loss of two of his stallions in consequence of probable poisoning. The affected animals were kept in the stable only. The mares, which were grazing on pasture during the day, were not affected. All the animals were fed the same type of feed. The day before the animals became sick, between 15:00 to 19:00 h the stable was not secured against the entry of strangers. When the mares were brought back to the stable and all animals were closed and locked for the night, no signs of health issues were observed. In the following morning, the two stallions were found in lateral recumbency with seizure attacks. Despite symptomatic treatment (infusion with saline, flunixine meglumine, activated charcoal) and applications of myorelaxants, the symptoms persisted until the afternoon, and the owner agreed with euthanasia. Based on the clinical signs and pathological examination, poisoning by pesticides was suspected. The results of toxicological analyses revealed that carbofuran, metaldehyde, and strychnine were not responsible for the poisoning as they were not detected in the samples. The only positive finding was a high aluminium concentration in the stomach content, liver and kidney samples. Based on the observed symptoms and the high aluminium concentration, it was presumed that aluminium phosphide could be the source of poisoning. As there was no evidence of the possession of such product by the horse breeder and the stable stayed unsupervised for a few hours, intentional poisoning cannot be excluded. Phosphine, pesticide, AlP In November 2018, a horse owner from the Czech Republic experienced the loss of two of his stallions in consequence of probable poisoning (weights 350 and 500 kg). Based on the very quick onset in more than one animal and the dominating clinical signs which were of neurological nature, the veterinarian suspected pesticide poisoning. The owner suspected intentional poisoning by an unknown person and the case was reported to the Police of the Czech Republic. Based on the case circumstances, there was a suspicion of aluminium phosphide poisoning. Metal phosphides are also commonly used pesticides. They are mainly used as rodenticides, with aluminium phosphide also used as insecticide during grain storage. In the Czech Republic, zinc phosphide can be used only by registered farmers, aluminium phosphide can be applied only by certified disinfection, disinsection and deratisation (DDD) companies. Less information is available for aluminium phosphide than for zinc phosphide; but in general, it is assumed to have similar properties and effects as zinc phosphide. After ingestion, aluminium phosphide is hydrolysed by water/humidity and hydrochloric acid present in the stomach to a gaseous product phosphine PH3, which is the active and poisonous agent (Peterson and Tallcott 2006; Gurjar et al. 2011; Hashemi-Domeneh et al. 2016). ACTA VET. BRNO 2020, 89: 231–237; https://doi.org/10.2754/avb202089030231 Address for correspondence: Zuzana Široká Department of Animal Protection and Welfare and Public Veterinary Medicine Faculty of Veterinary Hygiene and Ecology University of Veterinary and Pharmaceutical Sciences Brno Palackeho trida 1946/1, 61242 Brno, Czech Republic Phone: +420 541 562 779 E-mail: sirokaz@vfu.cz http://actavet.vfu.cz/