An investigation of metaldehyde and acetaldehyde toxicities in dogs.

Acetaldehyde has been reported, but has not been proven, to be the toxic entity resulting from metaldehyde ingestion. To investigate this, male dogs were given a single dose of 600 mg metaldehyde or acetaldehyde/kg of body wt via stomach tube. Clinical signs were monitored, and plasma and urine were assayed for metaldehyde and acetaldehyde. Vomiting occurred less often and in a significantly lower number of metaldehyde-dosed dogs than in acetaldehyde-dosed dogs. Ataxia and tremors occurred significantly more often in metaldehyde-dosed dogs than in acetaldehyde-dosed dogs. Acetaldehyde was not detected in the plasma or urine of metaldehyde-dosed dogs, however, it was found in a sample of vomitus from one of the metaldehyde-dosed dogs. Metaldehyde was found in plasma and urine of metaldehyde-dosed dogs. Urinary excretion of metaldehyde from the metaldehyde-dosed dogs was less than 1%. Urinary excretion of acetaldehyde from acetaldehyde-dosed dogs was essentially nonexistent. Metaldehyde has a larger role in the mechanism of metaldehyde toxicity than previously thought. While acetaldehyde appeared to be of significantly lesser importance, we could not eliminate it as a factor in metaldehyde toxicity in dogs.