Petfood from multiple brands have allegedly tested positive for acetaminophen, a common pain reliever, according to ExperTox, a laboratory in Texas. However, the US Food and Drug Administration (FDA) ruled out acetaminophen as a petfood contaminant after they found no trace of the substance in five samples of one type of cat and two types of dog food.

Donna Coneley, a spokesperson for ExperTox of Deer Park, Texas, USA, told Pet  Product News International that both wet and dry dog and cat food samples contained a low concentration of acetaminophen. In business since 1995, ExperTox was asked by "individuals or manufacturers" to analyze the petfood samples, Coneley said.

According to Julie Zawisza, assistant commissioner of public affairs for the FDA, a third lab hired by a petfood company and a university lab hired by a consumer could not verify ExperTox's findings. What is not yet clear is whether the FDA tested the same type of petfood in which ExperTox said it found the highest level of acetaminophen.

Coneley said her lab tested 100 to 150 samples of petfood-and detected acetaminophen in five of those samples. The company declined to name which petfoods had positive tests for acetaminophen, saying only that there were "multiple" brands involved.

ExperTox also found cyanuric acid and/or melamine in some of the samples, Coneley added. ExperTox is reportedly working closely with FDA officials to share their information and samples. Coneley says the company is standing behind their findings