Successful treatment of metaldehyde toxicosis with intravenous lipid emulsion in a dog

Abstract

The aim of the present report is to describe a novel successful treatment approach for metaldehyde poisoning in a dog: intravenous lipid emulsion therapy (ILE). A 2.5-month-old female Labrador Retriever was referred to the Emergency Department following deliberate ingestion of a metaldehyde-containing granular bait. Severe continuous tonic-clonic activity, muscle tremors, loss of consciousness, diffuse congestion of the oral mucosa, tachycardia, tachypnoea and nystagmus were observed upon admission. Additional intravenous administration of a 20% lipid emulsion resulted in normalization of the vital signs and complete neurological recovery. To the authors’ knowledge, this is the first report describing ILE in the treatment of canine metaldehyde intoxication and the first description of a case of metaldehyde poisoning in a dog in Romania. Considering the severity of the neurological signs and the fact that no specific antidote is known, treatment can be significantly challenging to the veterinary practitioner. This finding should be included in metaldehyde poisoning therapy protocols, especially when severe clinical signs fail to respond to symptomatic treatment. Poisoning, seizure, lipophilic, therapy, molluscicide, toxicity Metaldehyde is a cyclic tetramer of acetaldehyde, widely used to control slugs and snails in agriculture and household gardening (Yas-Natan et al. 2007; Gupta 2012). The World Health Organisation classifies metaldehyde as a class II toxin, whereas the Unites States Environmental Protection Agency classifies it as a slightly toxic chemical (class II or III) (Gupta 2012). Most frequently the exposure is oral, but the toxicant can also be absorbed from the skin and the lungs. After oral exposure, metaldehyde undergoes hydrolysis to acetaldehyde and it is further oxidized to acetic acid. Enterohepatic recycling of metaldehyde is also possible. Excretion is accomplished primarily through the urinary system and to a lesser extent through faeces, with a reported plasma half-life of 27 h (Gupta 2012). In dogs, the oral LD50 (median lethal dose) of metaldehyde is 100 mg/kg (Beasley 1999). Metaldehyde acts primarily as a neurotoxicant; clinical signs include hyperpnoea, tachycardia, nystagmus, mydriasis, hypersalivation, ataxia, seizures, acidosis, hyperesthesia, diarrhoea, dehydration, hyperthermia and death (Booze and Oehme 1985; Beasley 1999; Puschner 2001). There is no currently known antidote for metaldehyde toxicosis (Beasley 1999). The main objectives of the treatment include prevention of metaldehyde absorption, patient stabilization, management of the neurological signs and supportive care provision (Richardson et al. 2003). In recent years, successful use of intravenous lipid emulsion (ILE) in various intoxications with lipid soluble compounds has been reported. Since metaldehyde is a lipid soluble toxin ACTA VET. BRNO 2017, 86: 379–383; https://doi.org/10.2754/avb201786040379 Address for correspondence: Cristina A. Lelescu 3-5 Calea Mănăștur street 400372, Cluj-Napoca, Romania Phone: +40 (0) 743 082 264 E-mail: cristina.alexa.lelescu@gmail.com http://actavet.vfu.cz/ (Allen et al. 2004; Loftin 2012), the use of ILE as an adjuvant therapy in metaldehyde poisoning was investigated in a dog that failed to respond to symptomatic treatment.