Roundup, Rodeo and other weed and insect killers contain glyphosate. This chemical has been tested on dogs to determine its toxicity in canines and other mammals.
Glyphosate is a broad-spectrum herbicide. It can be used on cropland or for lawns and gardens. It is also a general-use pesticide, according to Cornell University.
Alone, glyphosate is not toxic to canines. When combined with a surfactant, as usually happens when it is used as an herbicide, glyphosate can cause respiratory distress, intestinal upset and kidney failure.
The onset of symptoms in dogs after ingestion of glyphosate can be delayed as long as 72 hours. A dog that has ingested glyopshate should be taken to a veterinarian, who can provide supportive care, according to "Environmental and Occupational Medicine."