Equine encephalomyelitis Flashcards
equine protozoal myeloencephalitis
sacrocytis neurona or Neospora hughesi
disease indicence: 1%
oppossums
common in NOrth and south America
Eastern states
most common in regions with moderate temperature
<5 yo adults at higher risk
EPM Epidemiology
performance horses: TB & WB>QH
increased incidence in fall
increased incidence when opossums present
decreased risk in rodent-proof containers used for grain
increased incidence if horse previously stressed
EPM pathogenesis
Sacrycystic neurona, Neospora hughesi
natural 2 host cycle
30-60% of horses are exposed and seroconvert
most horses do not develop CNS signs
focal, multifocal or diffuse, asymmetric nonsuppurative inflammatory lesions in the brain and spinal cord
What is the infective stage of sacrocytis neurona?
sporocyst
EPM clinical signs
dependant on area of CNS infestation
80% of cases only involve spinal cord
asymmetric
cerebral signs include: depression, changes in mentation and seizures
acute or insidious
rate of progression variable
asymmetric ataxia, weakness, CP deficits, muscle atrophy
obscure lameness
behavioral changes
CN deficits, narcolepsy like activity, urinary incontinence
EPM in brainstem
depression (RAS)
dysphagia (CN IX, X)
vestibular disorders (CN VIII)
facial paralysis (CNVII)
gait deficits-rubrospinal tract, UMN signs, conscious proprioception deficits
EPM spinal cord
gait deficits-UMN and LMN signs
sensory ataxia/weakness, asymmetric
muscle atropy-LMN sign
bladder atony
EPM diagnosis
clinical signs
CSF tap: WBC, RBC CK, protein, may be normal
detect abs in CSF: Western blot, IFAT test, SAG2/3/4 ELISA
EPM Treatment
banamine (anti-inflammatory)
ponazuril (marquis)-expensive
Sulfadiazine and pyrimethamine
EPM prognosis
varies with how quickly a dx is established and treatment is initiated
relapses are common
EPM prevention
Keep opossum burden low on farm
farms away from wooded areas have lower prevalence of disease
protect feed from opossums: feed grain indoors, covered hay racks
Vaccine
EHV-1 epidemiology
sporadic
adult horses
endemic
EHV-1 infection
respiratory
abortion (>50%)
neonatal death
neurologic (10%)
risk factors for neurologic form of EHV-1
latent state
stress
high fever on day 3
pregnant mares
any age
transmission: inhalation, contact, ingestion
incubation: 2-10d
Pathophysiology of EHV-1
spread via T lymphocytes
endotheliotropic-vasculitis
viremia precedes abortion, neurologic disease (white matter>gray matter)
