Lead poisoning is most common in dogs. In other species, lead poisoning is limited by reduced accessibility, more selective eating habits, or lower susceptibility. Lead poisoning is usually seen during renovation of old houses that have been painted with lead-based paint. Other sources of lead include linoleum, grease, lead weights, lead shot, lead fishing tackle, improperly disposed of oil and batteries, and contaminated foliage growing near smelters or along roadsides.
Absorbed lead enters the blood and soft tissues, and eventually reaches the bone. The amount of lead absorbed is influenced by dietary factors such as calcium or iron levels. Lead causes bleeding and swelling of the brain, suppresses the immune system, and damages the kidneys and red blood cells.
In dogs, gastrointestinal signs, including loss of appetite, colic, vomiting, and diarrhea or constipation, may be seen. Anxiety, hysterical barking, jaw champing, drooling, blindness, lack of coordination, muscle spasms (with backward arching of the head, neck, and spine), and convulsions may develop. The central nervous system can be either depressed or stimulated.
In horses, lead poisoning usually results in a longterm syndrome characterized by weight loss, depression, weakness, colic, diarrhea, paralysis of the larynx and throat (roaring), and difficulty swallowing that often results in aspiration pneumonia.
In birds, loss of appetite, coordination, and condition; wing and leg weakness; and anemia are the main signs.
Specific concentrations of lead measured in the blood, liver, or kidneys can help to confirm the diagnosis in most species and will reflect the level or duration of exposure. They can also be used to determine a prognosis and monitor the success of treatment. Lead poisoning can be confused with other diseases that cause nervous or gastrointestinal abnormalities. In dogs, rabies, distemper, and hepatitis may appear similar to lead poisoning.
If tissue damage is extensive, particularly to the nervous system, treatment may not be successful. The vitamin thiamine lessens signs and reduces tissue deposition of lead. In dogs, thiamine is given along with calcium disodium edetate (Ca-EDTA). d-Penicillamine can also be administered, but side effects include vomiting and loss of appetite. Succimer is another agent that is useful in dogs as well as birds. Medications that cause emptying of the bowels may be useful to remove lead from the gastrointestinal tract. Medications to control seizures may also be needed.