Lead Poisoning: Still a Concern for Pets

Dog drinking from water pipe
Isolated events, like the water crisis in Flint, Michigan, show how easily lead can contaminate our world.

While lead poisonings have become somewhat less common over the years due to greater awareness, I am amazed at all the ways pets still consume this substance and where it can be found in our environments. And certainly isolated events, like the recent drinking water crisis in Flint, Michigan, show that lead can easily contaminate our world, including the water both we and our pets drink.

Aside from drinking water, dogs, cats, and even birds and other exotic pets can be exposed to lead from many sources: automotive batteries, bone meal supplements, ceramic glazes (found on pottery, earthenware, bone china, porcelain), lead weights (fishing sinkers, curtain weights), lead-based paints (old houses, artist’s paints, some agricultural and marine paints), lead solder, putty, caulk, leaded gasoline, linoleum, electronic equipment, roofing felt and wine cork covers (pre-1996). While the incidence of lead poisoning has decreased due to the removal of lead from house paint and gasoline, you can see there are still many ways pets can gain access to this substance. Most cases in small animals occur when puppies chew woodwork or there is renovation going on in a home built before 1977. Animals that are shot with lead bullets or pellets can develop lead poisoning, especially if the retained bullet is in an acidic environment, such as the stomach, joint capsule or area of inflammation, like a bruise or abscess. The microenvironments of these areas are more acidic and can hasten the absorption of lead.

Lead is absorbed into the body through the gastrointestinal tract or by inhalation of dust. When cats and dogs groom themselves, they turn skin exposure into oral exposure. Young animals, just like children, absorb lead more readily than older animals, although no one knows exactly how. Lead is absorbed into the bloodstream and is bound to red blood cells. When this system is overwhelmed, lead distributes widely into the brain, bone, liver and kidney. Lead is stored long term in the bones.

Common Signs and Effects

Dogs and cats with lead poisoning most commonly show neurologic and gastrointestinal signs. They may have loss of appetite, behavior changes, tremors and seizures. Any of these signs should spark a call to your veterinarian. Chronic lead poisoning is more rare, but it can cause signs that include abdominal discomfort, vomiting, diarrhea, lethargy, weight loss, intermittent seizures and megaesophagus (which is a loss of muscle tone in the esophagus leading to dilation) in cats.

Lead interferes with multiple body systems. It causes cell death and brain function impairment. Lead is especially toxic to the fetus and young animals, as it inhibits brain development. It also affects red blood cells, causing anemia (which is when there are too few red blood cells in the blood) .

The diagnosis of lead poisoning is made by measuring whole blood lead levels. While the ideal blood lead level is zero, in most species, blood lead levels above 0.3-0.35 ppm (30-35 ug/dl) indicate significant lead exposure. Visually, lead objects can appear on X-rays and can be found in the gastrointestinal tract or, less commonly, as embedded lead projectiles, such as bullets and pellets, in the pet’s body.

Therapy to "Get the Lead Out"

Treatment of lead toxicosis can consist of several steps. Animals should be stabilized first and any life-threatening problems treated. Lead that is visible on X-rays should be removed if present. Chelation therapy should be started if needed. “Chelating agents” are substances that bind to metals like lead and help remove them from the body. Lead should be removed from the digestive tract before beginning chelation therapy, as many chelating agents may actually enhance absorption of lead. Different agents may be chosen by your veterinarian depending on their cost, availability and the pet’s clinical signs.

The prognosis in most cases is good with an early diagnosis and appropriate therapy. The source of the lead must be removed from the pet’s environment. Dogs and cats can also be important sentinels for human exposure. If your pet develops a case of lead poisoning, there could be the potential for human exposure to lead in the household as well. Local public health officials may be contacted for more information. If there is no obvious source of exposure in your home, a nalysis of water and soil may be needed in order to determine where your pet came in contact with lead.

While the presence of lead in our environment is, to some degree, ubiquitous, you can take steps to identify possible sources and prevent exposure ahead of time by using over-the-counter products to help test your home for lead paint and by doing an annual water test. Contact your local water supply for information or visit a home improvement store, as most usually stock kits that can test for the presence of lead in water or paint.

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