Equine Behaviroal Disorders

Question 1

Lesion location

Answer 1

Neural
Cerebrum
Brainstem
Extra neural
Liver failure
Renal failure

Question 2

Cerebrum

Answer 2

Dull, blind, seizures

Question 3

Brainstem

Answer 3

Dull, weakness/ataxia, cranial nerve dysfunction

Question 4

Adult differentials

Answer 4

Equine viral encephalomyelitis
Rabies
West Nile virus
Hepatic encephalopathy
Bacterial meningitis
Equine leukoencephalomalacia (moldy corn) rare

Question 5

Foal differentials

Answer 5

Neonatal encephalopathy
Bacterial meningitis

Question 6

Equine viral encephalomyelitis

Answer 6

3 different strains of virus
Eastern, western and Venezuelan
Virus persists in environment by asymptomatic infection of reservoir hosts (birds, reptiles, rodents)
Mosquitos are transfer hosts

Question 7

Risk of EVE

Answer 7

Peak season
Temperate climate: June-November
Subtropical: year round
Horses are sentinel animal for human risk * good idea to report

Question 8

presenting signs of EVE

Answer 8

Sudden onset of dullness, inappetence, fever, stiff
Hyperesthsia, aggressive, compulsive walking, blind, headpressing, circling, ataxia, head tilt, paralysis of pharynx, larynx or tongue

Question 9

Diagnosing EVEM

Answer 9

CBC: leukopenia
CSF: increased protein/leukocytes
PCR - antibody titer
Serology: four fold increase in antibody titer, high terminal titer

Question 10

Treating EVEM

Answer 10

No specific antiviral meds
Treat w anti inflammatories
Fluid therapy, nutritional support

Question 11

Prognosis for EVEM

Answer 11

Depends on strain of virus
EEE: 75-90% fatality
WEE: 25-50% fatality
VEE: 40-90% fatality
Survivors retain permanent deficits

Question 12

Prevention for EVEM

Answer 12

Monovalent bivalve t or trivalent killed vaccines
Initial 2 doses followed by annual vaccination
Protection for 6 months

Question 13

Equine rabies

Answer 13

Neurotrophic rhabdovirus
Transmitted by bite from infected animal
Long incubation period (3w-3m)

Question 14

Neurological exam findings for rabies

Answer 14

Dumb form: dullness, ataxia, weakness, Dysphagia, dysphonia
Furious form: aggression, hyperesthsia, seizures, tremors
Paralytic form: progressive ascending paresis/paralysis, flaccid tail

Question 15

Common findings with rabies

Answer 15

Paraparesis
Hyperesthsia
Aggression
Caudal hypotonia
Pharyngeal paralysis
Seizures
Self mutilation

Question 16

Course of rabies disease

Answer 16

Sudden onset of signs
Signs are rapidly progressive
Signs often change
Affected horse becomes recumbent
Invariably fatal disease (<14d)

Question 17

Diagnostic testing for rabies

Answer 17

CBC
Biochem profile
CSF analysis
ALL NORMAL ^#&$^$#$

Question 18

Postmortem rabies

Answer 18

Wear gloves***
Remove brain, send to state lab and place in formalin. Tests are conclusive and within 24-48 hrs

Question 19

Pathology for rabies

Answer 19

Postmortem exam - could have diffuse edema, congestion, hemorrhage
Lymphocytic perivascular cuffing
Neuronal degeneration
Negri bodies in horses w signs >4 days

Question 20

West Nile viral encephalomyelitis

Answer 20

Inflammatory disease of brain and spinal cord of horse caused by West Nile virus
Flava virus that resides in wild birds, transmitted via mosquitos

Question 21

WNVE epidemiology

Answer 21

Reported frequently in horses in Africa Middle East, Asia, southern Europe during 1900’s

Question 22

WNVE history /physical exam

Answer 22

Sudden onset of dullness and inappetence
Fever in 50% of cases
Neurologic signs = weakness, ataxia, muscle fasiculations, hyperesthsia, blindness
May progress to recumbency

Question 23

WNVE diagnostic tests

Answer 23

Antemortem - serum antibodies IgM ELISA
CSF analysis: mononuclear pleocytosis
Increased protein
Xanthochromia
Post mortem diagnosis by RT-PCR of tissues of CSF

Question 24

WNVE treatment

Answer 24

Supportive care - fluid therapy, enteral or parenteral nutrition, deep bedding
Anti inflammatory medications: flunixin, dexamethazone, dimethylosulfoxide

Question 25

WNVE vaccine

Answer 25

Variety of killed, recombinant DNA based vaccines
Initial two doses series administered 1 month apart
Temperate climate, annual vaccination
Subtropical climate, semi annual vaccination

Question 26

Neonatal encephalopathy

Answer 26

Non infectious neurologic signs in a foal immediate postpartum period
-neonatal maladjustment syndrome
- dummy foal syndrome
- hypoxic ischemia encephalopathy
Perinatal asphyxia syndrome

Question 27

NE history

Answer 27

Category 1
Delivery is uncomplicated
Foal is normal then sudden onset of neurologic signs within first 36 hours of life

Question 28

NE history category 2

Answer 28

Complicated pregnancy or delivery
Abnormal behavior at birth
Cerebral ischemia/hypoxia
Reperfusion injury

Question 29

NE neurologic exam

Answer 29

Reduced suckling reflex
Lack of affinity for mare
Dysphonia
Seizures

Question 30

NE diagnostic tests

Answer 30

CBC - normal
CSF - normal

Question 31

NE diagnosis

Answer 31

Presumptive
Sudden onset
Response to treatment in intensive care

Question 32

NE differential diagnosis

Answer 32

Hypoglycemia
Hypothermia
Head trauma
Septicemia
Bacterial meningitis

Question 33

NE treatment

Answer 33

Anticonvulsants (diazepam)
Anti inflammatory
Oxygen supplementation
Antibodies (colostrum)
IV fluid therapy
Nutritional support
GI supportive therapy

Question 34

NE prognosis

Answer 34

Majority completely recovery w intensive care
Prognosis is better if foal was born and signs were spontaneous
Prognosis is poor if foal was born dystocia w failure of passive transport