Accidental insulin-induced hypoglycemia in nondiabetic dogs

Insulin overdose requires a multi-tool diagnostic approach because a single test is not sensitive and specific for diagnosis. Herein, animal cases of insulin-induced hypoglycemia are presented in nondiabetic patients. We report an outbreak of iatrogenic insulin poisoning in dogs. Twenty dogs presented with peracute clinical signs, and seven were submitted for postmortem and histological examination in the Setor de Anatomia Patológica (SAP) at the Federal Rural University of Rio de Janeiro, Brazil. Tremors, inability to stand still, tachypnea, and intense vocalization were evident in 2 to 13 h of clinical evolution. All dogs had previously attended an anti-rabies vaccination campaign on the same day and time and showed peracute clinical signs after the application. The respondents reported suspicions about accidental parenteral administration of insulin in the dogs. Blood serum samples from the cardiac clot of the right ventricle of the dogs were sent for radioimmunoassay analysis to determine insulin dosage, and insulin was identified in three samples. Vitreous humor samples were submitted for flame atomic emission photometry and revealed low levels of potassium. Histologically, neuronal necrosis was observed in the temporal and frontal cortex. The epidemiological, clinical, and histopathological findings, along with the identification of insulin in the blood serum and atomic emission spectroscopy for potassium recovery, confirmed insulin poisoning. For the first time in veterinary medicine, accidental insulin-induced hypoglycemia is reported in nondiabetic dogs. Flame atomic emission photometry was a promising tool for indicating high circulating insulin levels in forensic veterinary medicine.