In its white (or yellow) form, phosphorus is hazardous to all domestic animals and is locally corrosive and hepatotoxic when absorbed. Phosphorus is infrequently used as a rodenticide today, but dogs occasionally become exposed through ingestion of fireworks that contain white phosphorus. The onset of signs of poisoning is sudden. Early signs include vomiting, severe diarrhea (often hemorrhagic), colic, and a garlic-like odor to the breath. Apparent recovery can occur up to 4 days after ingestion, but additional signs of acute liver damage may develop, including hemorrhages, abdominal pain, and icterus. Hepatic encephalopathy is followed by convulsions and death. Lesions include severe gastroenteritis; fatty liver; multiple hemorrhages; and black, tarry blood that fails to clot. Body tissues and fluids may be phosphorescent, and the gastric contents have a garlic odor. Death is due to hepatic and renal failure.

Prognosis is grave unless treatment is instituted early. A 1% solution of copper sulfate is an effective emetic and also forms a nonabsorbable copper phosphide complex. Gastric lavage with a 0.01–0.1% potassium permanganate solution or a 0.2–0.4% copper sulfate solution should be followed by activated charcoal adsorbent and 30 min later by a saline cathartic. Any fat in the diet must be avoided for 3–4 days or longer because fats favor additional absorption of phosphorus. Mineral oil orally has been recommended because it dissolves phosphorus and prevents absorption.

Last full review/revision March 2012 by Frederick W. Oehme, DVM, PhD