Paraquat is one of the few broad-spectrum herbicides available in the US; however, it is extremely toxic to companion animals when ingested. Despite its restricted use status, poisoning of dogs and cats remains relatively common. This clinical report documents a series of chronologically and geographically related cases of presumed malicious and fatal sub-acute paraquat poisoning in 7 dogs in Portland, OR. All animals developed acute gastrointestinal disturbance, renal compromise and insidiously progressive respiratory failure. Hyperlipasemia and moderate hypertension were notable featured in 5/7 cases. Trace levels of paraquat were demonstrated in the urine of 4/7 animals by gas-liquid chromatography/mass spectroscopy. Diagnosis in the remaining 3 cases was made through a combination of history or exposure, clinical signs and their progression, and pulmonary and renal histopathology.