Background

Ingestion of metaldehyde often causes acute neurological signs including hyperesthesia, hyperthermia, severe muscle tremors, respiratory depression and seizures. Treatment is mostly supportive, including decontamination procedures, anticonvulsive therapy and cardio-respiratory support. Since the 1980s, NMDA receptor antagonists are considered in the management of RSE. But only recently, ketamine has been used successfully for the management of refractory SE both in humans and dogs. This report describes the use of ketamine infusion as an adjunctive therapy for RSE in a dog presented for severe metaldehyde poisoning.

Case Presentation

A mixed breed, male, 5-year-old dog of 6 kg of weight was presented as an emergency for severe acute diffuse tremors after presumptive ingestion of metaldehyde. The dog showed moderate obtundation, heart rate of 180 bpm, respiratory rate of 70 bpm, congested oral mucous membrane, a mean arterial blood pressure of 120 mm Hg and a rectal temperature of 39°C. The time of ingestion was not confirmed. Animal was hospitalized and supportive therapy was started. A rapid deterioration of neurological status was observed and phenobarbital was administered at 5 mg/kg IM. The dog started to seizure, not controlled by the administration of 0.3 mg/kg midazolam IV. General anaesthesia was induced with propofol at 5 mg/kg IV, followed by intubation and maintenance of anaesthesia with isoflurane and oxygen. ECG, NIBP, and temperature were monitored. Despite general anaesthesia, the dog continued to show tremors, not responsive to the administration of a further 5 mg/kg IM phenobarbital. In order to control seizures with optimal cardiovascular support, ketamine infusion at 1 mg/kg/h IV was initiated and ET-Iso progressively reduced. After 30 minutes, tremors markedly reduced and vital signs were stable. Anaesthesia was maintained with ketamine infusion at 1 mg/kg/h IV for 8 hours, and an enema with active charcoal was performed. After 8 hours, ketamine dose infusion was progressively reduced to 0.3 mg/kg/h and continued for 6 hours, and the dog was extubated. No more seizures or tremors were observed, and the dog recovered uneventfully.

Unique Information

The first description of the successful use of a ketamine infusion to control RSE in a metaldehyde-poisoned dog.

Disclosures

No disclosures to report.