The glyphosate found in Roundup is not harmful to dogs when the product is used according to the manufacturer's directions. However, the company does advise that pets should be kept away from the product until it has completely dried.
Studies have shown that glyphosate has no toxic effect on dogs when ingested in small amounts daily and is not easily absorbed by the digestive tract. The chemical does not produce adverse effects on blood chemistry, cellular structure, reproductive capabilities or organ function. Glyphosphate has not been shown to be a carcinogen, although lab tests conducted on mice showed that lifetime exposure to the chemical resulted in reduced weight gain and minimal liver and kidney changes.