Clinical features of avian vacuolar myelinopathy in American coots.
OBJECTIVE
To characterize clinical features of avian vacuolar myelinopathy (AVM) in American coots.


METHODS
Case-control study.


METHODS
26 AVM-affected American coots and 12 unaffected coots.


METHODS
Complete physical, neurologic, hematologic, and plasma biochemical evaluations were performed. Affected coots received supportive care. All coots died or were euthanatized, and AVM status was confirmed via histopathologic findings.


RESULTS
3 severely affected coots were euthanatized immediately after examination. Seventeen affected coots were found dead within 7 days of admission, but 5 affected coots survived > 21 days and had signs of clinical recovery. Abnormal physical examination findings appeared to be related to general debilitation. Ataxia (88%), decreased withdrawal reflexes (88%), proprioceptive deficits (81%), decreased vent responses (69%), beak or tongue weakness (42%), and head tremors (31%), as well as absent pupillary light responses (46%), anisocoria (15%), apparent blindness (4%), nystagmus (4%), and strabismus (4%) were detected. Few gross abnormalities were detected at necropsy, but histologically, all AVM-affected coots had severe vacuolation of white matter of the brain. None of the control coots had vacuolation.


CONCLUSIONS
Although there was considerable variability in form and severity of clinical neurologic abnormalities, clinical signs common in AVM-affected birds were identified. Clinical recovery of some AVM-affected coots can occur when supportive care is administered. Until the etiology is identified, caution should be exercised when rehabilitating and releasing coots thought to be affected by AVM.
Larsen
R Scott
RS
Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh 27606, USA.
Nutter
Felicia B
FB
Augspurger
Tom
T
Rocke
Tonie E
TE
Tomlinson
Lindsay
L
Thomas
Nancy J
NJ
Stoskopf
Michael K
MK
D000818:Animals; D001715:Bird Diseases / Q000097:blood / Q000473:pathology* / Q000503:physiopathology; D001717:Birds; D001774:Blood Chemical Analysis / Q000662:veterinary; D001921:Brain / Q000473:pathology*; D001927:Brain Diseases / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D016022:Case-Control Studies; D009186:Myelin Sheath / Q000473:pathology* / Q000648:ultrastructure; D009412:Nerve Fibers / Q000473:pathology; D009460:Neurologic Examination / Q000662:veterinary; D010808:Physical Examination / Q000662:veterinary; D011379:Prognosis; D014617:Vacuoles / Q000473:pathology