The most common cause of lead poisoning in pets is ingestion of lead-based paint. Although lead-based paint is no longer available in the United States, it was used in buildings for many years. When these buildings are renovated or become weathered, the lead-based paint can contaminate the soil. Pets digging in the soil can become exposed to the lead paint, and then self-grooming or other methods of ingestion can occur.
Lead can also be obtained via other sources: toys, fishing tackle, drapery weights, solder, gasoline exhaust, car batteries, plumbing materials and supplies, lubricating compounds, putty or tar paper, lead foil, golf balls, food packaging, and improperly glazed ceramic food or water bowls. Water is rarely an important source of lead poisoning.
Puppies and younger dogs are more likely to chew on foreign objects, so they tend to be affected more often than older dogs. Cats rarely chew on such items, so they are more likely to get lead poisoning from self-grooming. Lead affects the stability of the red blood cell (RBC) membrane. Young animals have a greater susceptibility to lead because of an increased blood-brain barrier permeability to lead, as well as greater absorption rates.
Signs of lead poisoning in dogs include behavior changes (lethargy, aggression, constant snapping, seizures, hysteria, hiding in dark areas, and depression), frothing at the mouth, anorexia (lack of appetite), weight loss, vomiting, and diarrhea. Signs in cats include anorexia (loss of appetite), vomiting, diarrhea, and seizures. The toxic dose of lead in pets is 10 to 15 mg/kg when given as a single dose. However, signs of poisoning can occur from low-level chronic poisoning (5 mg/kg body weight per day).
Diagnostic tests include urine testing, complete blood count (CBC), and blood chemistry. Radiographs may be required to determine if there is a lead object in the gastrointestinal tract.
Treatment includes removal of the lead source (endoscopy, surgery), decontamination (gastric lavage, enemas, activated charcoal, cathartics), and chelation therapy. (Lead binds to the chelating agents; this allows the lead to be excreted from the body.)
Prognosis depends on the severity of signs and the length of time the signs were present. Most animals do not have residual neurological signs after recovery.
If lead intoxication is diagnosed in a pet, the owner should be warned of the possibility of human exposure to environmental lead.