Pets should not be allowed into an area that has been treated with Roundup until the product has fully dried. According to the National Pesticide Information Center, the active ingredient in Roundup weed killer, glyphosate, is low in toxicity, but additional ingredients that help plants absorb the glyphosate may be harmful to pets if consumed while the product is still wet.
According to the official Roundup website, the product presents little or no risk to pets or wildlife, so long as it is used in accordance with the label. Pets that eat plants that are wet with weed killer containing glyphosate may vomit, drool or have diarrhea, according to the National Pesticide Information Center. Pets may also become sleepy or lose their appetites.
An additional reason to wait until Roundup is dry before allowing pets to enter a treated area is to ensure that the product is not spread from the targeted weeds to other plants. Glyphosate is non-selective and kills any plant it comes into contact with. Once applied, Roundup is either absorbed by the plants that have been treated or binded to the surrounding soil. The product is then broken down by bacteria in the soil. Depending on the climate and type of soil, glyphosate may remain present for up to six months.