by Alison Bowler

Created on: November 04, 2009   Last Updated: January 05, 2010

The incidence of lead poisoning in humans has decreased markedly since public awareness of the condition led to a decrease in the amount of lead in the environment. However, animals do still develop lead poisoning and dogs are one on the most common animals to exhibit the signs of lead poisoning.

Dogs swallow lead from old house paint, fishing weights, old lead toys, improperly glazed ceramics and many other sources. Once poisoned the condition may be fatal unless the dog’s owner seeks veterinary assistance. Even with prompt veterinary care, fatalities occur in cases of severe lead poisoning.

Lead is a heavy metal capable of accumulating in an animal’s system. Within an animal, it interferes with the production of red blood cells. High levels of lead attack the central nervous system. It is also an irritant. As such, it inflames the gastrointestinal tract.

A dog poisoned by lead exhibits a number of signs. Inflammation of the gastrointestinal tract causes a loss of appetite, vomiting and abdominal tenderness. Initially the dog is constipated then develops diarrhea. Poisoning of the central nervous system causes chomping of jaws, excessive salivation, hysterical barking, blindness, seizures, muscle spasms, behavioral changes and circling. The dog frequently appears uncoordinated and may assume a stiffened posture with an arched back. A blood test reveals low hemoglobin as well as abnormal shapes and sizes of red blood cells (anisocytosis and poikilocytosis). The presence of young nucleated red blood cells in a blood film further shows the poison’s affect on red cell production. A blood lead level in excess of 0.35 ppm confirms a diagnosis of lead poisoning. Tissue lead levels exceed 10 ppm in lead poisoning and fecal levels exceed 0.75 ppm.

In acute lead poisoning, the vet may induce vomiting to remove any lead still in the dog’s stomach. Barbiturates or tranquillizers aid the controlling of any convulsions experienced by the dog.

Treatment to remove lead from a dog’s blood and tissues relies on the use of a chelating agent. Chelating agents bind to the lead ions forming a soluble complex that the kidneys can remove from the blood stream.  A number of chelating agents are used by vets for the treatment of lead poisoning including calcium disodium ethylene-diamine-tetra-acetate (Ca-EDTA), thiamine, d-Penicillamine and succimer (meso 2,3-dimercaptosuccinic acid, DMSA). They require repeated treatments over a number of days sometimes the course needs repeating after a break of a week. Treatment success is confirmed by a blood test for lead levels.

Reference sources:

Pet Education.com

Merck Veterinary Manual

Pro Vet.co

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