The Price of Freedom: How our Choice to use Lead is Killing the Bald Eagle (Part 2)

This post was originally published at Science@CornellVet on August 2, 2017 by Melissa Hanson, third year Cornell DVM student.  

A juvenile bald eagle receives treatment at the Janet L. Swanson Wildlife Health Center

Last week offered a glimpse into the work the Animal Health Diagnostic Center and Wildlife Health Team has done to quantify the impact of lead on our native wildlife, but what does the story look like from the perspective of Cornell’s clinicians? Dr. Sara Childs-Sanford, a veterinarian at the Janet L. Swanson’s Wildlife Health Center, a clinical service of the Cornell University Hospital for Animals (CUHA), shared her experience treating local wildlife directly impacted by the toxic element.

“A typical patient presenting with lead toxicity is a raptor species (bird of prey) or waterfowl. These animals are weak, and often have neurologic signs and ileus (failure of food to pass through the digestive tract),” says Childs-Sanford. “Concerned members of the public usually bring the animal to CUHA after observing it unable to fly or walk.”

She explains that the primary treatment of these animals involves supportive care for dehydration and emaciation, and a blood draw to screen for serum lead values. Her team uses an in-house lead analyzer is to detect lead concentration in the blood, giving them a rapid answer regarding lead toxicity in a patient.

With the help of the analyzer, virtually every raptor or waterfowl species patient that comes through the door is screened for lead toxicity, allowing treatment to begin immediately. To target the lead, the Wildlife Health Center team uses chelation therapy, which involves the introduction of compounds that bind lead and thus allow it to be excreted by the patient. Chelation therapy is completed in five day increments for a minimum of two weeks, but many patients need to remain under the care of Childs-Sanford’s team or a wildlife rehabilitator for much longer.

What harm can a little lead do? When ingested by an animal, lead is absorbed through the blood stream where it disrupts heme synthesis, a process required for oxygen delivery. The toxin is then distributed throughout the body where it deposits in soft tissue, organs, and bone, degenerating nerves and interrupting signaling pathways necessary for neurologic and gastrointestinal function. The prognosis for patients is widely variable and dependent upon the levels of lead detected, the organ systems affected, and most importantly, how long the toxicity has been present. In general, acutely affected animals carry a better prognosis than those with chronic exposure. Unfortunately, for waterfowl and piscivorous raptors, continually eating from a contaminated body of water often results in the latter.

Radiograph of a common loon with a lead sinker visible in the digestive tract

So, what can you do to help? For Childs-Sanford, part of the solution is clear: don’t use lead bullets or sinkers, and don’t cut fishing lines into the water. “Lead in the wild comes from people,” she stated, noting that its inexpensiveness and the lack of public awareness of its effects are likely to blame for its continued use. While the Wildlife Health Center is capable of treating animals on an individual basis, the true answer to the lead problem lies in addressing its source—us. Increased education for hunters and fishermen is vital, and eliminating the use of lead materials in our environment is the only way to save our wildlife from its devastating effects. Until then, Childs-Sanford and her team will take it one patient at a time.

ABOUT THE AUTHOR

Melissa is a third-year veterinary student from Cortlandt Manor, New York. She received her Bachelor of Science degree from Duquesne University where she majored in biology and minored in biochemistry and history. Her interests are in clinical zoo and wildlife medicine and particularly rescue, rehabilitation, and release. She works as student technician at the Janet L. Swanson Wildlife Health Center, a service of the Cornell University Hospital for Animals.