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Equine Med and Surgery II > Lecture 4: Diseases of Nervous System: infectious > Flashcards

Lecture 4: Diseases of Nervous System: infectious Flashcards

1
Q

What is the primary reservoir for viral encephalitides

A

bird species

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2
Q

what transfers viral encephalitides to horses and humans

A

mosquitoes

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3
Q

what is the pathophysiology of viral encephalitis

A
  1. Virus enters CNS by crossing BBB through endothelial cell penetration
  2. Affects cerebral cortices, thalamus, hypothalamus, and sometimes spinal cord (less affected)
  3. Neurophagia and gliosis progressing to malaria and necrosis
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4
Q

which viral encephalitis has the greatest affect on the spinal cord

A

WNV

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5
Q

what are some clinical signs of viral encephalitis 1-3 days with infection

A

fever, depression, anorexia, fire is

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6
Q

what are some clinical signs of viral encephalitis 1-3 days following fever

A

hyper excitability progressing to somnolence, depression, recumbency, cortical blindness, propulsive walking, head pressing, ataxia

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7
Q

what is the mortality to eastern equine encephalitis

A

75-99%

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8
Q

T or F: horses are dead end hosts for EEE

A

true, don’t transmit

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9
Q

what is the morality rate for western equine encephalitis

A

20-50%

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10
Q

T or F: horses are dead end hosts for WEE

A

true, don’t transmit

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11
Q

what is the mortality rate of Venezuelan equine encephalitis

A

20-80%

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12
Q

T or F: horses are dead end hosts for VEE

A

false, horses can become viremic and primary reservoirs- infect you and other horses

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13
Q

what is the mortality rare for West Nile virus

A

2%

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14
Q

what is the best way to diagnose viral encephalitides

A

Serology- IgM capture ELISA can distinguish between vaccinated >30-60 days and natural infection

Rapid and reliable

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15
Q

what are some CSF findings for WNV

A

mononuclear pleocytosis, variable protein

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16
Q

what are some CSF findings for EEE

A

high protein, neutrophilic marked pleocytosis

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17
Q

what are some CSF findings for WEE

A

lymphocytic pleocytosis

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18
Q

how can you dx viral encephalitides post mortem

A

viral isolation on brain tissue

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19
Q

what is the tx for viral encephalitides

A
  1. Supportive care (ineffective for EEE)
  2. Corticosteroids-reduce brain edema
  3. Mannitol- reduce brain edema
  4. NSAIDS (best in WNV)
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20
Q

how do you prevent viral encephalitides

A
  1. Yearly vaccination prior to mosquito season
  2. Mosquito control
21
Q

what does EHV-1 cause

A

respiratory disease, neurological disease, abortion storms/ weak foals, chorioretinopathy

22
Q

what does EHV-2 cause

A

respiratory disease and keratoconjunctivitis

23
Q

what does EHV-3 cause

A

coital exanthema

24
Q

what does EHV-4 cause

A

respiratory disease, rarely associated with abortion and neurological disease

25
Q

what does EHV-5 cause

A

equine multinodular pulmonary fibrosis

26
Q

what is the pathophysiology of EHV 1 and 4

A
  1. Virus enters respiratory system and transported to LN
  2. Virus enters peripheral WBCs and circulates blood
  3. Results in vasculitis and thrombosis
27
Q

what genetic variant in EHV-1 is commonly associated with neurological disease

A

mutation of aspartic acid (D) instead of asparagine (N) at position 752 in DNA polymerase gene

28
Q

T or F: avoid testing healthy horses for herpes because they all have it

A

true

29
Q

what is the test of choice for herpesvirus

A

real time PCR of nasal swab or fresh whole blood

30
Q

what are the clinical sides of EHV neurotrophic form

A

fever, dog sitting, upper motor neuron bladder (turgid, unable to void, spastic)

31
Q

what areas of the spinal cord are most commonly affected with EHV

A

caudal spinal cord and sacral cord

32
Q

what are the CSF findings of EHV

A
  1. Increased total protein
  2. Xanthochromia (yellow color)
33
Q

how can you prevent neurological signs in horses exposed to EHV

A
  1. Valcyclovir/ valganciclovir decreased viral replication and signs
  2. LMW heparin to prevent thrombosis
  3. Banamine
34
Q

what is treatment for EHV

A
  1. NSAIDS
  2. Corticosteroids
  3. Monitor urination- catheterization and antimicrobials to prevent septic cystitis
  4. Anticoagulant therapy- LMW heparin
  5. Antiviral drugs to decrease shedding
  6. Quarantine for 3 weeks past last fever
35
Q

how do you prevent EHV

A
  1. Minimize stress
  2. Vaccinate q3 months
  3. High virus neutralizing antibody vaccines
36
Q

what horses should be vaccinated against EHV/when to vaccinate

A

afebrile and asymptomatic

37
Q

what vaccines for eHV have greatest ability to limit nasal shedding and viremia

A
  1. Antiabortion vaccines- pneumabort-K and prodigy
  2. MLV vaccines: rhino use and calvenza
38
Q

how long do horses exposed to eHV have immunity

A

3-6 months

39
Q

what is prognosis for EHV

A
  1. Good for non recumbent horses
  2. Poor for recumbent horses
40
Q

what causes EPM

A

sarcocystis neurons or neospora hugheshi

41
Q

what is the definitive host for EPM

A

opossums

42
Q

what are some clinical signs of EPM

A

Ataxia, weakness, dysphagia, head tilt, obtundation, facial nerve paralysis, muscle atrophy, switching leg lameness

43
Q

how can you dx EPM

A
  1. Rule out other differentials
  2. Serum IFAT
  3. Serum to CSF ration- best one
  4. Necropsy- demonstrate protozoans in CNS lesions- gold standard
44
Q

which diagnostic test for EPM has a high negative predicative value and what does that mean

A

western blot- a negative result means strong likelihood you dont have EPM, a + result is not helpful

45
Q

what is tx for EPM

A
  1. Thiazide coccidiostats- Marquis ponazuril, portability-diclazuril
  2. Folate inhibitor combination-sulfadiazine/pyrimethamine
46
Q

what is prognosis for EPM

A
  1. 60% of horses will improve 1 grade
  2. 10-20% will relapse
47
Q

T or F: good idea to vaccinate against EPM

A

false, doesn’t work well and complicates diagnosis

48
Q

how do you manage a grade 5 neurological horse

A
  1. Inform owner 1 in 10 horses ever stand again
  2. Refer- heavily sedate in trailer
  3. Wrap legs and head in trailer for protection
  4. Isolate, quiet and dark, deep bedding and padded stalls
  5. Monitor ability to eat and drink, IV fluids
  6. Turn recumbent horses every 2-4hrs

Equine Med and Surgery II (4 decks)

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