Additional Information from Dr. Dave McRuer

Additional Information Provided by Dr. Dave McRuer, Director of Veterinary Medicine

Eagle #09-2530

We first performed a very quick physical exam on Eagle #09-2530 as the bird was too unstable to conduct an immediate extensive evaluation. It was noted that the bird's response to external stimuli (toe pinch) was weak and it had trouble standing. These clinical signs are common in lead poisoned birds as the nervous system is one of the major organ systems affected. Crackling noises could be heard in the lungs and indicated congestion or fluid build-up. Some amount of swelling was found around the face and neck causing mild respiratory distress. No signs of blood in the mouth were found at this time although reported in the history before admission. The bird was given fluids under the skin to hydrate and help stabilize, an iron injection for blood loss, opioids for the pain, and a non-steroidal anti-inflammatory drug for the swelling. A small blood sample was taken to test for lead toxicity. The total concentration of lead in the blood was too high for our machine to read; treatment (a chelator called Calcium EDTA) was administered to bind to lead in the blood and take it out of the body. The bird was given the night to rest and stabilize and X-rays were performed the next day. The x-rays showed two buckshot pellets in the stomach and indicated the source of the lead poisoning. As these pellets were too large to pass through the GI tract, and the pellets could not be removed with an endoscope, the bird was immediately taken to surgery and the pellets were removed. For the next few days, the bird showed obvious signs of toxicity (green stool, drooped head and wings, other neurologic deficits). The bird continued to be given the previously listed meds as well as a few others to encourage GI motility. The eagle was fed several times a day with a calorically dense gruel through a tube. Three days later, the neuro signs were much improved and the blood lead levels had dropped to the subclinical range. However, a week after admission, the bird could not stand and the weakness returned to the legs. These signs progressed and despite subclinical blood lead levels, the bird was found dead in the cage on January 5th. A complete necropsy was performed and no unobserved injuries were found other than some fluid in the lungs. It is posited that the bird died from permanent peripheral nerve damage due to the high blood lead levels. Although the total initial lead concentration was not known (we've sent away a sample to test it and are waiting for results) , it was likely that it was higher than 1 ppm, a level that almost always leads to permanent nerve damage in this species. Typically, we see an influx in lead-ingestion cases at this time of year that is directly correlated with the deer hunting season (This has been shown very nicely also in Minnesota). When hunters leave the gut piles in the woods instead of burying them, eagles and vultures consumer the left-overs which are laced with lead fragments. In one study, fragments were demonstrated to be found with a deer carcass up to 18 inches away from the trajectory of the bullet. We likely only admit a VERY small fraction of the animals that are affected by lead. In a field study conducted in the 70's, 1000 dead, bright yellow, day-old chicks were scattered throughout a marsh. Twenty-four hours later, a search team performed a standardized grid search to see how many could be retrieved. They found one percent! This likely occurs with all dead or injured wildlife due to scavenging and predation. Some additional resources on lead:  This (http://www.youtube.com/watch?v=NyZLxobg5k0) is an interesting interview with Dr. Luis Cruz of the Minnesota Raptor Center. He does a lot of work on lead toxicosis in Bald Eagles in that state and is a huge proponent of getting deer hunters to switch from traditional lead bullets to newer non-toxic copper bullets. Second, the Peregrine Fund sponsored a great meeting two years ago on Ingestion of Lead Ammunition: Implications for Wildlife and Humans. (http://www.peregrinefund.org/Lead_conference/default.htm)  There is a ton of great information found under "proceedings"; various presentations may be downloaded.  This is the specific article dealing with bald eagles and lead in Minnesota (http://www.peregrinefund.org/Lead_conference/PDF/0208%20Redig.pdf).