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Ruminant Medicine Spring 2016 > L5: Neuro Dz Of Ruminants Pt.1 (MacKay) > Flashcards

L5: Neuro Dz Of Ruminants Pt.1 (MacKay) Flashcards

1
Q

Diencephalon =

A

Thalamus + Hypothalamus

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2
Q

Prosencephalon (forebrain) =

A

Telencephalon + Diencephalon

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3
Q

Symptoms of forebrain disease

A
  • seizures
  • dementia (head pressing, compulsive walking, excessive vocalization, teeth grinding, self-mutilation, hyperesthesia)
  • blindness
  • mental depression (obtunded)
  • decorticate/decerebrate posturing
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4
Q

Hydrocephalus

A

Too much water in the ventricular system/CSF of the brain

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5
Q

Hydranencephaly

A

Replacement of brain parenchyma with water (usually in forebrain tissue)

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6
Q

Causes of Hydrocephalus/Hydranencephaly

A

1) Genetic:
- aqueductal stenosis due to neuropathic hydrocephalus in Angus
2) Acquired:
- fetal bluetongue, BVD infection
- fetal Akabane, Schmallenburg viruses
- Vit. A def. in the dam
- bacterial meningitis

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7
Q

CS of Hydrocephalus/Hydranencephaly

A
  • classic forebrain signs (blind, wandering, dummies, seizures, lack of maternal bonding)
  • generally stunted
  • failure of passive transfer –> 2ary sepsis**
  • domed forehead
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8
Q

Dx of Hydrocephalus/Hydranencephaly

A
  • domed skull
  • genetic testing
  • cortical signs
  • precolostral blood PCR, serology, virus isolation
  • Ig quantification
  • cross-sectional imaging
  • necropsy
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9
Q

Infectious causes of neuro dz in ruminants

A
  • Neonatal bovine suppurative meningitis*
  • Thromboembolic meningoencephalitis (TEME)
  • Sporadic bovine encephalitis (SBE, Buss disease)
  • Brain abscess/pituitary abscess*
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10
Q

Meningitis most commonly affects what populations?

A

-neonates

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11
Q

Etiology of neonatal suppurative bovine meningitis (NSBM)

A
  • hematogenous from gut, umbilicus
  • direct from dehorning, tail docking, environment
  • failure of passive transfer most common cause**
  • most common pathogens assoc. with failure of passive transfer: E. Coli, Trueperella pyogenes, gram negs
  • primary pathogens (not from FPT): Salmonella, mycoplasma
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12
Q

CS of neonatal suppurative bovine meningitis (NSBM)

A
  • fever
  • neck stiffness
  • hyperethesia
  • blind, seizures
  • nystagmus, obtunded
  • recumbent, coma
  • sepsis signs (ie. Septic vasculitis)
  • decerebrate
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13
Q

Dx of neonatal suppurative bovine meningitis (NSBM)

A
  • CS
  • plasma protein conc. (FPT)
  • CSF tap: xanthrochromia, bacteria, neutrophilic pleocytosis (degenerate PMNs)
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14
Q

Tx of neonatal suppurative bovine meningitis (NSBM)

A
  • euthanize
  • dexamethasone
  • abx (Ceftiofur 10 mg/kg IV q12hr, enrofloxacin)**
  • hypertonic saline if opisthotonus
  • blood/plasma for FPT
  • anticonvulsant
  • supportive
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15
Q

Telencephalon =

A

Cerebrum

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16
Q

CS of cerebral abscess

A

Asymmetric forebrain signs

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17
Q

CS of pituitary abscess/basilar empyema

A
  • blindness

- obtundation, cranial nerves

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18
Q

Causes of brain/pituitary abscess

A
  • adjacent infecton
  • penetrating wound
  • nose rings (pituitary)
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19
Q

Viral causes neuro dz in ruminants

A

Pseudorabies
Rabies
Malignant catharral fever
Bovine herpes encephalomyelitis

20
Q

Pseudorabies (Mad Itch)

A
  • caused by alpha herpesvirus
  • pigs are carriers
  • CS: fever, self-mutilation, pruritus, dementia, ataxia
  • usually die within days*
  • endemic in feral pigs in FL
  • reportable dz
  • > 95% mortality
21
Q

Rabies virus, CS, forms

A
  • Rhabdoviridae genus lyssavirus
  • centripetal then centrifugal
  • CS: fever, hypersalivation, can’t swallow, hydrophobia, metabolic acidosis, tenesmus, etc.

Forms:

  • furious: forebrain, classic rabies
  • dumb: brainstem, obtunded
  • paralytic: spinal cord, polymyolitis
22
Q

Dx of rabies

A
  • mild mononuclear pleocytosis
  • Negri bodies
  • FA staining frozen sections
23
Q

Prevention of rabies

A
  • kill/quarantine suspects/exposed
  • PEP for valuable animals (ie. Texas protocol)
  • rabies vax
24
Q

Malignant Catarrhal Fever

A
  • y-herpesvirus
  • sheep are carriers
  • CS: fever, obtundation, aggression, ataxia, “white eye,” lymphadenopathy, diarrhea
  • 95% mortality
25
Q

Bovine Herpesvirus Encephalomyelitis

A
  • alpha herpesvirus
  • outbreaks in S. America
  • fatal in calves
26
Q

Transmissible Spongiform Encephalopathies (TSE)

A 
BSE
Scrapie
CWD
CJD
Mink encephalopathy
27
Q

CS and course of BSE

A

CS: forebrain signs esp. Apprehension, aggression, self mutilation; ataxia, m. Spasms, wt. loss

Clinical course = 1-6 mo. And fatal

28
Q

Cause of BSE

A

Prions

  • unique infectious protein that has no RNA or DNA
  • has ability to transform normal PrPc proteins to abnormal form
  • prions found in CNS, bone marrow, GI
29
Q

BSE Surveillance

A
  • rapid immunotests for PrPsc
  • histology
  • sample of obex (brain tissue under the cerebellum)
  • IHC is official test
30
Q

Scrapie

A
  • affects sheep and goats (sheep > goats)
  • distinct from BSE
  • present in lymphoid tissues AND CNS (different from BSE)
  • transmission: peri-natal, or between adults
  • more common in black-faced sheep (can have PrPc gene polymorphism)
  • endemic but rare
  • similar CS as BSE
31
Q

Scrapie eradication program

A
  • genetic testing (blood samples)
  • certification of negative herds
  • live animal testing: 3rd eyelid, rectal biopsy
32
Q

Nutritional/Toxic causes of neuro dz in ruminants**

A
  • Salt poisoning/water intoxication*
  • lead poisoning*
  • polioencephalomalacia (thiamine)*
  • polioenchephalomalacia (sulfur toxicity)*
  • vit. A deficiency
  • non-protein nitrogen toxicity
  • = causes laminar cortical necrosis
  • all have CS, but lead poisoning causes the most mania*
  • more signs of colic in lead/salt poisoning than poliocephalomalacias*
33
Q

Pathophys. of salt poisoning/water toxicity

A
  • high salt or water deprivation
  • high Na –> brain shrinking/hemorrhage
  • water repletion –> brain swelling
  • water toxicity by itself doesn’t cause CNS problems
  • improperly mixed milk replacer is most common cause

> 50% mortality

34
Q

CS of salt poisoning/water toxicity

A

Forebrain signs, then brainstem signs (opisthotonus, ataxia, limb weakness, coma) as brain swells up against calvarium and puts pressure on brainstem

GI signs: colic, d

35
Q

Dx of salt poisoning/water toxicity

A 
Hx
High Na (>1 CSF: plasma ratio)
36
Q

Tx of salt poisoning/water toxicity

A

IV 0.9% saline (can give IV saline and withhold milk), +/- 10-20 ml hypersaline/L
Monitor plasma Na
Aternative: small amounts of oral saline or milk slowly
Dexamethasone

37
Q

CS of acute lead poisoning

A
  • Hyperesthesia, bellowing, blindness
  • twitching facial muscles
  • progress to recumbency
  • GI signs
  • MANIA
38
Q

CS of subacute/chronic lead poisoning

A
  • blindness

- diarrhea

39
Q

Dx of lead poisoning

A
  • blood lead > 0.35 ppm
  • urine ALA concentration
  • tissue lead (post-mortem)
  • CBC in subacute cases: polychromasia, basophilic stippling
40
Q

Tx of lead poisoning

A
  • Sedation (ie. Valium to prevent seizures)
  • rumenotomy, MgSO4 (reduces bioavailability)
  • EDTA chelation therapy
  • thiamine (supports glucose metabolism in CNS)
  • support
  • fair prognosis w/ tx
41
Q

Polioencephalomalacia: Thiamine deficiency

A
  • can affect all ruminants/camelids (usually weanlings)
  • sporadic outbreaks
  • assoc. with overfeeding/roughage underfeeding/feed change/deworming
42
Q

CS/Tx of thiamine deficiency

A

CS: bilateral dorsomedial strabismus***, star-gazing, seizures, wandering, etc.

Central vision can take a long time to recover**

Tx:

  • thiamine 10-20 mg/kg slow IV, SC, IM BID-QID
  • dexamethasone
  • rumenal transfaunation
  • support
43
Q

Polioencephalomalacia: Sulfur Toxicity

A
  • assoc. with feedlots, well water, distillers grain by-products**, molasses, anionic diets –> sulfur ingestion
  • supportive tx only; can give thiamine
  • sulfur is converted to H2S gas in the rumen –> eructation –> inhalation –> CNS toxin
44
Q

Metabolic conditions that cause neuro dz in ruminNRA

A 
Hepatoencephalopathy (protolaria ? Plant most common cause)
Nervous Ketosis
Electrolyte abnormalities
Hypoglycemia
Hypomagnesemia
Early hypocalcemia
45
Q

Nervous ketosis

A
  • during early lactation
  • ketonuric
  • causes cerebral signs: licking, head-pressing
  • tx: IV dextrose, oral propylene glycol, dexamethasone

Ruminant Medicine Spring 2016 (18 decks)

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