Unit 4 - Equine CNS Flashcards
What are the infectious causes of cortical neurologic disease?
EEE/WEE/VEE Rabies WNV Bacterial meningitis Brain abscesses
What are the etiologic agents of equine encephalomyelitis?
Western Equine Encephalitis virus
Eastern Equine Encephalitis virus
Venezuelan Equine Encephalitis virus
What is equine encephalomyelitis transmitted by?
Mosquitos
Which of the etiologic agents of equine encephalomyelitis is has no bird involvment and is an FAD?
VEE
What are the reservoir for EEE and WEE?
Birds
What are the dead end hosts for EEE and WEE?
Horses and humans
T/F: Horses are not a dead end host for VEE.
True
Where is EEE found geographically?
Easter, southern, and midwestern states
Where is WEE found geographically?
It is widely disseminated across the US and Canada
Where is VEE found geographically?
Central and South America
Rate the equine encephalomyelitis viruses from most to least severe.
EEE»_space; VEE > WEE
Mortality rates follow this trend too
What clinical signs are associated with equine encephalomyelitis?
Initial onset of fever, anorexia, and depression
Rapid progression to central neurologic signs
Peracute cases may be found dead
The neurologic form of equine encephalomyelitis is also called what?
Sleeping sickness
What neurologic signs are associated with equine encephalomyelitis?
Ataxia, decreased vision, wandering, drowsiness, photophobia, head pressing, and paralysis
What age group of animals are most susceptible to equine encephalomyelitis?
Young animals < 5years
What is the best antemortem diagnostic for equine encephalomyelitis?
IgM capture ELISA (>1:400 indicative)
Aside from IgM capture ELISA, how is equine encephalomyelitis diagnosed?
Suggestive based on the time of year and location in animal without history of a recent vaccination CSF tap PCR and IHC VI Paired serum if survival is long enough
How is equine encephalomyelitis treated?
Supportive care - hydration/nutrition, neuro stall/sling, urination/defecation
Anti-inflammatoris - NSAIDs preferred
How is equine encephalomyelitis prevented and controlled?
Mosquito control
Vaccination
What are the reservoir hosts for West Nile Virus (WNV)?
Birds
What spreads WNV?
Mosquitos
What clinical sign is somewhat unique to WNV that should move it to the top of your list if they are exhibiting it?
Muscle fasciculations - muzzle twitching
What are the most common clinical signs associated with WNV?
Weakness or ataxia
Altered mentation, recumbency
T/F: WNV can be fatal in horses and chronic neurologic deficits are common
True
How is WNV diagnosed?
Suggestive based on time of year and clinical signs in an animal without a history of recent vaccination CSF tap IgM antibody capture ELISA PCR, IHC, VI Paired serum
What will the CSF tap show in patients with WNV?
Non-specific lymphocytic pleocytosis and elevated TP, possibly mononuclear pleocytosis
How is WNV treated?
Supportive care - hydration/nutrition, neuro stall/sling, urination/defecation
Anti-inflammatoris - NSAIDs preferred
How is WNV prevented and controlled?
Mosquito control
Vaccination
What is the etiologic agent of rabies?
Rabies virus - neurotropic rhabdovirus
What species is rabies most commonly associated with in the midwest?
skunks and raccoons
What is the most common form of transmission of rabies in the US?
Bite of the infected animal
What is the range for the incubation period for rabies?
It ranges from 2-9 weeks depending on the location of bite
Rabies is considered the great imitator. Why?
It can initially present as a lameness, colic fever of unknown origin, pharyngeal paralysis, hyperesthesia, ataxia, recumbency, any neurologic sign, abnormal vocalization
What are the three main forms of rabies?
Furious - infects brain
Dumb - infects brain stem
Paralytic - infects spine
T/F: Rabies is always fatal
True
How is rabies diagnosed?
Clinical signs
Direct or indirect FA test at necropsy
Negri bodies
How is rabies treated?
It isnt
How is rabies prevented?
Vaccination
Re-vaccinate post-exposure and quarantine for 45 days
Contact public health officials if not vaccinate and exposed
What are the infectious causes of brainstem/CN neurologic disease?
Guttural pouch mycosis
Otitis media
T/F: There are no infectious causes of cerebellar neurologic disease.
True
What are the infectious causes of spinal and peripheral nerve neurologic disease?
EHM EPM Tetanus Spinal abscesses Verminous meningoencephalomyelitis
How is EHV-1 myeloencephalopathy transmitted?
Respiratory, direct contact, or fomites
EHV-1 myeloencephalopathy is a ______ associated viremia. ______ cell damage causes an inflammatory cascade and _____ causing ______ injury.
Leukocyte
Endothelial
Thrombosis
Ischemic
What age group of horses are more commonly affected by EHM?
Older horses
What clinical signs are associated with EHM?
Transient fever
Acute onset of ataxia and tetraparesis that may progress to recumbency
Urinary incontinence, bladder distension, weak tail/anal tone
When does the onset of EHM clinical signs occur?
6-10 days after infection
What is the average mortality rate of EHM?
50%
How is EHM diagnosed?
Tentative based on CS and history CSF PCR 4 fold increase in titers Necropsy
What will a CSF tap show in a patient with EHM?
Xanthochromia with increased protein and normal cell count
How is EHM treated?
Immediate isolation Supportive care - fluids and nutritional support Anti-inflammatories Antivirals \+/- Heparin
How is EHM prevented and controled?
Prevent introduction of new virus strains
What is the protocol for EHM prevention/control in case of outbreaks?
CONTACT THE STATE VET - reportable
Quarantine the premesis and isolation of all clinical animals 2 weeks past all clinical signs
Twice daily temperature monitoring
What is the etiologic agent of equine protozoal myeloencephalitis (EPM)?
Sarcocystis neurona
What is the definitive host of Sarcocystis neurona?
Opossum
How is Sarcocystis neurona transmitted?
Ingestion of feed or water contaminated with opossum feces
What clinical signs are associated with EPM?
They vary greatly - can infect any part of the CNS so almost any neurologic sign is possible (spinal cord»_space; brain, asymmetric > symmetric)
Limb weakness and ataxia
How is EPM diagnosed?
Serology
CSF antibody titers
PCR on CSG
Necropsy - may find protozoa but absence doesn’t rule it out
How is EPM treated?
Anti-protozoal medications (28 days)
Supportive care - NSAIDs, Vitamin E, corn oil
How is EPM prevented and controlled?
Protect feed and water sources from opossum feces
Avoid stress and steroid use
+/- preventative utilization of ponazuril or diclazuril
What is the etiologic agent of tetanus?
Clostridium tetani
How can horses become infected with tetanus?
Via spore formation in the environment or contamination of wounds with spores from environment
What is the pathogenesis of tetanus infection?
Tetanospasmin binds irreversibly to presynaptic inhibitory neurons resulting in muscle rigidity and spasms
Tetanus clinical signs can develop up to ___ months after wound inoculation.
2
What clinical signs are associated with the early stages of tetanus?
Startling by loud noises leads to sudden spastic paralysis
What clinical signs are associated with later stages of tetanus?
Continuous muscle spasms and rigidity
Head and neck - lockjaw, 3rd eyelid prolapse
Sawhorse stance
Tail elevation
How is tetanus diagnosed?
Lack of ID of wounds in many cases
Clinical signs in the absence of recent vaccination
How is tetanus treated?
Administration of antitoxin if unvaccinated or status unknown
Debride wounds
Penicillin
Supportive care
T/F: There is a low mortality rate associated with tetanus, but a prolonged recovery time.
False - high mortality rate
How is tetanus prevented and controlled?
Vaccination, booster vax following injury
What are the infectious causes of motor unit/peripheral nerve neurologic disease?
Botulism
What is the etiologic agent of Botulism?
Clostridium botulinum
T/F: Botulism is contagious.
False - tis not
What are the 3 routes of infection of botulism?
Ingestion, wounds, ingestion of performed toxin
What clinical signs (general) are associated with botulism?
Flaccid paralysis and death from paralysis of respiratory muscles within 48-72 hours
What clinical signs are associated with foals that have botulism?
Initially less active, rest with head on the ground
Drag hooves when walking
Progress to down and unable to rise
What clinical signs are associated with Botulism in adults?
Dysphagia, tongue weakness, muscle tremors, abnormal great, progress to ataxia and recumbency
How is botulism diagnosed?
Detection of toxin in serum or feed - PCR or ELISA
How is botulism treated?
Early administration of antitoxin
Supportive care
How is botulism prevented and controlled?
Vaccination in endemic areas
