Livestock Neurology

Question 1

What is the pathogenesis of polioencephalomalacia?

Answer 1

Thiamine (B12) metabolism dysregulation
Decreased Na/K, decreased H2O transport leads to neuronal dysfunction and swelling = laminar cortical necrosis
Key Co-Factors = transketolase and pyruvate dehydrogenase

Question 2

What clinical signs are associated with poliocencephalomalacia?

Answer 2

Ataxia
Proprioceptive deficits
Altered mentation (aggression, lethargy)
Cranial nerve deficits
Seizures, coma, death
Cortical blindness (CN II = absent menace) (CN II and III = functional PLR)

Question 3

How is polioencephalomalacia treated/prevented?

Answer 3

Supplement with thiamine (Vitamin B1)
Adapt to high grain diets, prevent free choice grain
Limit dietary sulfur

Question 4

How is salt toxicity diagnosed?

Answer 4

History and clinical signs
Serum or CSF Na > 160mmol/L
CSF:Serum Na > 1
CSF osmolarity > mOsm/L

Question 5

How is salt toxicity treated?

Answer 5

SLOWLY decrease serum Na
Corticosteroids, thiamin, supportive care
Prognosis is poor

Question 6

What is the pathophysiology of lead toxicity?

Answer 6

Pb inhibits enzymes at Cu, Zn, and Fe binding sites, inhibiting heme synthesis and decreasing RBC life
CNS hemorrhage and edema

Question 7

How is lead toxicity diagnosed?

Answer 7

Normocytic, normochromic anemia
Basophilic stippling on RBCs

Question 8

How is lead toxicity treated?

Answer 8

Ca EDTA chelation
Thiamine

Question 9

What is the most common form of rabies in cattle?

Answer 9

Paralytic form: flaccid paralysis

Question 10

What are the clinical signs associated with the 3 forms of rabies?

Answer 10

Dumb: lethargy
Paralytic: flaccid paralysis
Furious: hyperexcitable, fear, rage
Others: vocalization, pruritus, ataxia, lameness, dysphagia

Question 11

How is rabies diagnosed?

Answer 11

Post-mortem IFAT on brain tissue or presence of negri bodies

Question 12

What is the pathophysiology of Bovine Spongiform Encephalopathy/Scrapie?

Answer 12

Abnormal form of protein induces conformation change, disrupting normal cell functions

Question 13

How is bovine spongiform encephalopathy transmitted?

Answer 13

Feeding rendered animal proteins from infected animal

Question 14

How is Scrapie transmitted?

Answer 14

Classical: horizontal and vertical
Disease is not heritable but susceptibility is
Atypical: spontaneous mutation

Question 15

What clinical signs are associated with bovine spongiform encephalopathy

Answer 15

Behavior changes
Ptyalism
Reluctance to be milked
Fasciculations
Proprioceptive deficits
Abnormal gait
Licking

Question 16

What clinical signs are associated with Scrapie?

Answer 16

Behavior changes
Pruritus
Biting, licking, grinding teeth
Goats are ‘more aware’
Weight loss
Abnormal gait/ataxia
Cannibalism

Question 17

How is bovine spongiform encephalopathy diagnosed?

Answer 17

Histopathology for spongiform lesions
Western blot

Question 18

How is Scrapie diagnosed?

Answer 18

3rd eyelid or rectal mucosal biopsy
Histopathology on specific brain region

Question 19

How is scrapie prevented in sheep?

Answer 19

Genetic testing for resistance (only for classical!!)

Question 20

What clinical signs are associated with listeriosis cattle?

Answer 20

Fever (early)
Anorexia, lethargy
Ataxia, head pressing
CN V - XII deficits (usually symmetric)

Question 21

How is listeriosis diagnosed?

Answer 21

Clinical signs
CSF: increased mononuclear cells, cloudy, increased protein
Abscessed in brain on necropsy

Question 22

How is listeriosis treated/prevented?

Answer 22

Long-term abx and supportive care
Remove source, prevent contamination

Question 23

What is the etiologic agent of thromboembolic meningoencephalitis?

Answer 23

Histophilus somni

Question 24

What are the clinical signs of thromboembolic meningoencephalitis?

Answer 24

Fever
Usually asymmetric signs
Brainstem and CN signs
Ocular: retinal hemorrhages, hyphema, hypopyon
Others: respiratory, polyarthritis, reproduction, ears, udder

Question 25

What is the pathophysiology of thromboembolic meningoencephalitis?

Answer 25

Respiratory disease --> septicemia Microthrombi and micronecrosis Thromboses due to clotting cascade

Question 26

How is thromboembolic meningoencephalitis diagnosed?

Answer 26

CSF: increased protein and neutrophils, hemorrhage, and xanthrochromia CBC: septicemia Suppurative meningitis, necrotic meningoencephalitis

Question 27

How is thromboembolic meningoencephalitis treated/prevented?

Answer 27

Abx (oxytetracyclines) Vaccination

Question 28

What are the hosts associated with parelaphostrongylus tenuis?

Answer 28

Definitive: white tailed deer (no clinical signs, adults live in subarachnoid space and cerebrospinal venous sinuses) Intermediate: slugs and snails

Question 29

What are the clinical signs associated with parelaphostrongylus tenuis?

Answer 29

Posterior paresis Ataxia Proprioceptive deficit CSF: eosinophilia, increased protein

Question 30

How is parelaphostrongylus tenuis treated?

Answer 30

Fenbendazole injections (larvae in CNS) Ivermectin injections (circulating larvae only)

Question 31

What are the clinical signs of cerebellar disease?

Answer 31

Proprioceptive deficits Head tremor Opisthotonus Strabismus Nystagmus Hypermetria

Question 32

What CNS lesions are associated with BVDV?

Answer 32

Cerebellar hypoplasia Hydrancephaly Hydrocephalus Hypomyelinogenesis

Question 33

What are the clinical signs of cervical spinal cord disease in cattle?

Answer 33

Weakness/quadriplegia Ataxia Proprioceptive deficits Hyperreflexia (pelvic > thoracic) Respiratory, cardiac arrest Stiff neck/neck pain

Question 34

What are the clinical signs of thoracic spinal cord disease in cattle?

Answer 34

Thoracic limb weakness Pelvic limb ataxia Pelvic limb hyperreflexia If sternal, pelvic limbs extended and not tucked under Dog sitting

Question 35

What are the clinical signs of lumbar spinal cord disease in cattle?

Answer 35

Thoracic limbs normal Pelvic limb ataxia Pelvic limb hyyperreflexia Urine and fecal incontinence

Question 36

What are the clinical signs of sacral spinal cord disease in cattle?

Answer 36

Thoracic limbs normal Pelvic limb weakness Flaccid tail and anal tone Urine and fecal incontinence

Question 37

What is the pathophysiology of tick paralysis?

Answer 37

Blocks Ach release at NMJ

Question 38

What are the clinical signs of tick paralysis?

Answer 38

Ascending flaccid paralysis Increasing stumbling/weakness Increasing recumbency Respiratory failure and death Anorexia

Question 39

How is tick paralysis treated?

Answer 39

Shear Injectable ivermectin!

Question 40

Answer 40

Suprascapular n paralysis Sweeney

Question 41

Answer 41

Radial n paralysis

Question 42

Answer 42

Femoral n paralysis

Question 43

What are the clinical signs of femoral nerve paralysis?

Answer 43

Difficulty rising Inability to fix stifle 1-day-old calf with posterior delivery

Question 44

Answer 44

Sciatic n paralysis - peroneal

Question 45

Answer 45

Sciatic n paralysis - tibial

Question 46

Answer 46

Obturator n paralysis

Question 47

What nerves are involved in calf paralysis?

Answer 47

Sciatic, obturator n Inability to bear weight = sciatic, tibial n Knuckling of fetlock - peroneal