Equine neurological disease

Question 1

What viruses with primary neurotropism cause equine neurological disease?

Answer 1

Rabies

Bornavirus

Question 2

Which arboviruses cause equine neurological disease?

Answer 2

Japanese encephalitis

West Nile Virus

Question 3

Which viruses cause neuropathy by damaging the BBB?

Answer 3

EHV-1 and 4

Equine infectious anaemia

Question 4

Which equine neurological diseases are parasitic?

Answer 4

Halicephalobus gingivalis
Strongylus vulgaris
Hypoderma
Trypanosoma

Question 5

Which equine neurological diseases are caused by clostridial neurotoxins?

Answer 5

Botulism

Tetanus

Question 6

What are neurological diagnoses usually made on?

Answer 6

History 
Clinical exam
CSF analysis
Medical imaging
Functional testing
Post mortem

Question 7

What history should be noted when examining for neurological diseases?

Answer 7

Info about geographical location
Recent travel history
Vaccination history
Onset/duration of clinical signs

Question 8

CSF analysis is key in most viral encephalitis. What do you look for in CSF analysis that indicates a neurological problem?

Answer 8

Increased protein
Mononulcear pleocytosis (increased cell count)
Identify Ag or specific Ab

Question 9

What medical imaging can be used to diagnose neurological problems? What are disadvantages are this?

Answer 9

CT
MRI
EEG
Expensive and only up to mid cervical region

Question 10

What treatment should be given if suspecting a neurological problem? (fever, neurological signs)

Answer 10

Isolate - presume infection
Quiet, dark stable
Deep bedding
Padded walls 
Turn recumbent horses every few hours
Sling if stood
NSAIDs, corticosteroids, antiviral therapy

Question 11

How can neurological diseases be prevented?

Answer 11

Vaccination if available

Minimise exposure to vector or reservoir

Question 12

What is EHV-2?

Answer 12

Keratitis

Question 13

What is EHV-3?

Answer 13

Coital exanthema

Question 14

What is EHV-4?

Answer 14

Respiratory

Question 15

What is EHV-5?

Answer 15

Multinodular pulmonary fibrosis

Question 16

What does EHV 6-8 affect?

Answer 16

Donkeys

Question 17

What type of virus is equine herpes? What immunity do horses have to this?

Answer 17

Alpha herpes virus
DNA virus
Hummoral immunity is short lived - naturally low Ab level

Question 18

What is EHV-1?

Answer 18

Respiratory
Abortion
Myeloencephalopathy

Question 19

What are the clinical signs of EHV-1? What are these signs a result of?

Answer 19

Sudden onset 
Ataxia and recumbency
Atony of bladder
Flaccid tail and anus
Perineal hypoalgesia
Cranial nerve involvement
Signs due to vasculitis and thrombosis of arterioles in CNS

Question 20

What is the treatment and prognosis for EHV-1?

Answer 20

Isolate, give anti-inflammatories for vasculitis

Prognosis reasonable with good care, except if recumbent for long time periods

Question 21

Is there a vaccination for EHV? What are problems with this vaccine?

Answer 21

For EHV1 and EHV4

Question 22

Rabies is an important zoonotic disease but is quite uncommon in horses. What is the pathogenesis of rabies?

Answer 22

Salivary/droplet transmission via carnivore bite
Inoculates at wound site
Travels to peripheral nerve
Moves centrally and replicates in spinal/dorsal root ganglia
Spreads to CNS

Question 23

There are few clinical signs for rabies as it turns from mild lameness to sudden death. The signs vary based on which form of rabies it is. What are the 3 forms of rabies?

Answer 23

Spinal form - parayltic form
Cerebral form - furious form
Brain stem - dumb form

Question 24

Spinal/parayltic rabies is the most common form. What are the clinical signs of this?

Answer 24

Localised hyperaestheisa
Progressive ataxia
Weakness
Lameness
Recumbency

Question 25

What are the clinical signs of the brain stem/dum form of rabies?

Answer 25

Depression Anorexia Ataxia

Question 26

What are the clinical signs of the cerebrum/furious form of rabies?

Answer 26

``` Photo/hydrophobia Aggression Bizarre behaviour Muscle tremors and tetanus Seizures ```

Question 27

Rabies is always fatal. Is there a vaccination? What should you do if suspected rabies?

Answer 27

yes | Kill if suspected

Question 28

How is rabies diagnosed

Answer 28

Post mortem exam - careful as zoonotic | Negri bodies in neurons

Question 29

What causes West Nile virus?

Answer 29

Flaviviridae (group B arbovirus)

Question 30

West Nile Virus is found in humans and horses in Africa and America. What are the reservoir hosts? How is the disease transmitted to horses and humans?

Answer 30

Birds | Spread via mosquitoes + midges

Question 31

What is the pathogenesis of West Nile Virus?

Answer 31

virus replicates at inoculation site Causes viraemia and signs of infection (fever, depression) Enters CNS of some horses

Question 32

What are the neurological signs of West Nile Virus?

Answer 32

``` Weakness Ataxia Muscle twitches - particularly in head/neck Affects mentation Can cause sudden death ```

Question 33

How is West Nile virus diagnosed and treated?

Answer 33

Dx - ELISA, post mortem | Tx - hyperimmune specific plasma (USA), supportive care (NSAIDs, corticosteroids)

Question 34

What is the prognosis and prevention for West Nile Virus?

Answer 34

Some cases gradually resolve but have long term neurological defects Reduce vector contact (mosquito repellents) and vaccination