Avian Vacuolar Myelinopathy in a bald eagle ( Haliaeetus leucocephalus )

1. Avian Vacuolar Myelinopathy in a bald eagle (Haliaeetus leucocephalus) • Jey Koehler1, Fred Hoerr2, Marie Rush3, Jamie Bellah3 • Auburn University Department of Pathobiology • Thompson-Bishop-Sparks Diagnostic Laboratory • Southeastern Raptor Rehabilitation Center Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

2. Signalment • Young adult female bald eagle, estimated to be approximately 4-4.5 years old based on cere color, iris color and plumage Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

3. History • Found on a family farm close to West Point Lake near the Alabama-Georgia state line, flew into the side of a barn in an attempt to escape, brought to SERRC • On presentation, no palpable fractures or trauma, right nare was partially obstructed with a mass of debris/tissue, and the bird was observed to be “hock-sitting” • Good BCS, good appetite, limb weakness, weak grasp, unable to perch Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

4. History • Clin path revealed heterophilia and markedly increased CK • Treated with fluids, broad spectrum antibiotics, antifungals, CaEDTAchelation • Over the next 3 days, the bird developed rapidly progressive ascending weakness, ataxic movements, culminating in recumbency and death: submitted to AVDL for necropsy January 2, 2008 Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

5. Gross findings excellent body condition moderate post-mortem degeneration stomach contents consisted of rodent remains multifocal to coalescing linear areas of pale pink-tan fibers mild congestion of meningeal vessels Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

6. cerebrum, 4x Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

7. cerebellum, 4x Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

8. brainstem, 4x Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

9. brainstem, 40x Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

10. Ancillary testing • PCR testing for avian influenza and West Nile virus were negative • Toxin testing for arsenic and lead was negative • Selenium levels in the liver were not significantly altered Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

11. Diagnosis Vacuolar leukoencephalopathy, diffuse, marked, subacute, consistent with avian vacuolar myelinopathy. Additional diagnosis: Myopathy, multifocal, moderate to marked, subacute to chronic. (consistent with an exertional myopathy) Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

12. Avian Vacuolar Myelinopathy • Relatively newly recognized disease affecting bald eagles, coots, and several other species of birds in the southeastern United States, first epornitics in Arkansas in 1994-1995 and 1996-1997 (55 eagles) • An unidentified neurotoxin linked to aquatic vegetation has been implicated, and the disease has been experimentally induced in birds by both feeding of aquatic vegetation from lakes at which AVM is occurring and feeding of AVM-infected tissue • Infection of waterfowl is thought to be the first stage in the cycle, followed by ingestion of carcasses by carnivorous birds; generally occurs during the winter migratory months, October to April Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

13. Avian Vacuolar Myelinopathy • Tissues from the birds in the Arkansas epornitic were subjected to an exhaustive battery of toxicologic testing, none of which showed significant evidence of known toxins as etiologic agents • Although exhaustive testing for chemicals known to induce white-matter vacuolation in mammals was not performed on this eagle, the combination of clinical history, geographic location, and characteristic histopathological lesions was considered sufficient to warrant a diagnosis of AVM Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

14. Cases documented as being • suspected or confirmed as the • cause of death at Clarks Hill/ • J. Strom Thurmond Lake between 1998-2004 by • SCWDS in a 2006 JWD paper • by Fischer, et al: • 28 bald eagles • 17-94% of coots annually • 16 Canada geese • 6 American coots • 2 great-horned owls • 1 killdeer • No lesions seen in beavers, • raccoons, gray fox collected • near the lake during • surveillance Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

15. Special thanks to: • Dr. Fred Hoerr at Thompson-Bishop-Sparks State Diagnostic Lab (AVDL) • Drs. Marie Rush, Jamie Bellah, and Ms. Liz Crandall at the Southeast Raptor Rehabilitation Center • The staff at the histology labs of both the AVDL and Auburn University, especially Ms. Beth Landreth Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

16. References • Thomas, N.J., Meteyer, C.U., Sileo, L.: Epizootic Vacuolar Myelinopathy of the Central Nervous System of Bald Eagles (Haliaeetusleucocephalus) and American Coots (Fulicaamericana). Veterinary Pathology 35: 479-487 (1998). • Fischer, J.R., Lewis-Weis, L.A., Tate, C.M., Gaydos, J.K., Gerhold, R.W., Poppenga, R.H.: Avian Vacuolar Myelinopathy Outbreaks and a Southeastern Resevoir. Journal of Wildlife Diseases 42(3): 501-510 (2006). Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only

17. Presented at SEVPAC 2008 – Permission granted for use on SEVPAC website only