Ruminant neuro Flashcards
What is the most common cause of seizures in both goats & sheep?
polioencephalomalacia
What are causes of polioencephalomalacia?
-excessive sulfur consumption
-altered thiamine metabolism
-salt poisoning or water deprivation
-amprolium admin
-rations of molasses & urea
-Pb intoxication
Thiamine deficiency in PEM is pathologic because important in what cycles?
rate limiting enzyme in hexose monophosphate pathway– krebs cycle
What examples of bacteria and plants that produce thiaminases?
-bacillus thiaminolyticus, costridium sporogenes
-plants: bracken fern (pteridium aquilinum), horse tail (E. arvense), Nardoo fern (marsilea drummondii)
What is the sulfur role in development of PEM- pathologic mechanism?
-INC ruminal sulfide ** overwhelm hepatic index detox capacity
-cattle inhale ruminal gas (bypass hepatic circulation)
PB and sulfur can cause PEM by what mechanism?
**impair ATP production
–affect electron transport sim to sulfide
What are clinical signs of subacute PEM polioencephalomalacia?
symmetric
-blind
walk with head held erect
slight hyeprmetric gait
progresses to bilat cortical blindness
head pressing
opisthotonos
bilat
dorsomed strabismus
miosis
repetitve chewing
profuse pytalism
defective menace response
variable nystagumus
INC HR, RR
what are clinical signs of acute form of PEM polioencephalomalacia?
recumbent
comatose
episodic tonic-clonic convulsions
-recumbent & hypertonic between seizures
What are ddx for PEM polioencephalomalacia?
lactic acidosis
carbohydrate engorgement
ruminal tympany
enterotoxemia
salt poisoning/water deprivation
head trauma
bact meningoencephalitis
coccidoiosis w/ NS invovlement
vit A def
ethylene glycol poisoning
locoism
rabies
IBR encephalitis
What does CSF for PEM polioencephalomalacia look like?
mild pleocytosis: 5 to 50 WBCs with voaculoation
INC protein concen: >50 mg/dL
what is the treatment of polioencephalomalacia PEM?
thiamine
dexamethasone
mannitol
amtimicrobial admin
control convulsions: phenobarb, pentobarb, diazepam
ruminants with PEM secondary to molasses-urea diet don’t respond to what treatmetn?
–thiamine administration
** respond to glucose or oral glucose precursor
What are preventative measures to be taken for polioencephalomalacia?
-allow appropriate time to adjust to high concen. rations
-feedstuff analysis routinely: ID source too high in sulfur, remove high sulfur hay, ammonium sulfate, molasses
-thiamine supplementation
-brewers yeast
-gypsium
-cobalt
Water intoxication occurs when?
concurrent with period of restricted access to water followed by unrestricted access to water
Water intoxication pathogenesis
disease occurs once water enters extracellular fluid and moves to brain tissue
What are feedstuffs that are common sources of excess NaCL?
whey
saline preserved fish or fish meals
bakery by-products
-milk replacers or oral electroltye solutoins
-brine (flush during teh drilling of oil wells)
Acute salt intoxication occurs when
ignestion of large quantity of NaCl
chronic salt intoxication occurs when
long periods with decreased water consumption with low-mod salt intake
What is the pathogenesis of hyeprnatremia?
imbalance in sodium & water regulation
– INC in sodium plasma concentration
- causes movement of intracellular water into ECF= cellular dehydration
With chronic hypernatremia, when are clinical signs seen?
with osmotic adpatation in brain– no C/S seen until treatment with rapidly dec plasma concentraiton Na IVF
or drinking lg quantities of water
When are gastrointestinal signs seen with salt toxicity?
-large quantities of salt ingested over short time period
– intestinal lumen hyperosmolarity
(saline catharsis, osmotic diarrhea)
What C/S are seen with salt intoxication?
GI and neuro signs
– Stargazing, constant chewing movement, coma, dec milk production, blindness, aggressiveness, hyperexcitability, psychomotor seizures nystagmus vocalization
with salt intoxication, what is seen on serum and CSF?
serum/CSF concen: >160 mEq/L
>1:1 CSF: serum ratio
OR
brain NA concen >150 mEq/g or 1800ppm
What is seeing on necropsy with salt intoxication?
cerebral edema
softening & flattening of cortical gyri
microscopic lesions: laminar cortical necrosis, poliomalacia, +/- mengineal or perivascular infiltration of eos or monos
Ruminants have a tendency to lick or chew objects that lead to lead poisoning. What are potential sources of Pb?
PB arsenate defoliants
PB acid batteries
used motor oils
linoleum
roofing felt
paint
machinery grease
caulking compounds
improperly compounded mineral supplements
foliage- near smelters & battery recycling plants
What are factors that increase likelihood of ingestion?
lack of alternative feedstuffs
hunger
phosphorus deficiency
Lead toxicity influenced by what dietary factors?
calves on milk– INC correlation with Vit D and enhanced Pb absorption
Copper-pastures fertilized with pig slurry, potentiate accumulation of lead
What are the toxic effects of lead?
-inhibition of free sulfhydryl groups in many enzymes
-interference with zinc containing metalloproteins
-steric inhibition of enzyme activity
-enzymes of heme synthesis susceptible to injury– shortens RBC half-life
What are C/S of lead toxicity?
-hyperesthesia, muscular fasciculations, rapid fast twitching eyelids/facial mm
-progression: ataxia, CP deficits, cortical blindness, head pressing, ondotprisis, coma, convulsions, bellowing death
-GI signs: bloat, diarrhea, rumen atony, colic
-infertility
-abortions
-fetal malformations
What is the preferred diagnosis of lead toxicosis?
blood concen: free RBC porphyrins and RBC concen delta-aminolevulinic acid
When collecting blood for diagnosis of pb levels, what tube should you use?
heparin to collect blood b/c does not chelate blood
What can be administered intravenously to in low lead tox poisoning levels?
EDTA– solubilizes the bone lead stores adn INC the concen in plasma then excreted in urine
What is seen on radiographs in young animals chronically exposed to lead?
“lead lines”–radiopaque transverse bands & metaphyses of long bones
Why is anhydrous ammonia added to poor quality feed?
-improves nutrtional density
-dec certain fungal toxic metbaolites
-inc DML
-enhances digestibility
-inc protein value
Cause of cow bonkers
overammoniation >3% forage DMI
with lead toxicity, what is the effect on calves
toxin concentration in milk– calves show C/S
What C/S are seen with ammoniated forage tox/Cow bonkers?
hyperasthetic
ataxia
sawhorse stance- at rest
vocalization
dysphonia
walking/running into objects
when excited: hyperactive, blind (appear), circle propulsively
What is the toxic principle of cow bonkers?
diakylimdazoles
r-methylimidazole
ammoniated forage toxicosis/ bovine bonkers is seen at what level?
ammoniated >3% of forage on dry matter basis
When are clinical signs of ammoniated forage toxicosis/bovine bonkers worse?
worsen with hyperexcitability
Listeriosis can manifest as what forms of disease?
neonate septicemia
abortion
neonatal death
ophthalmitis
uveitis
diarrhea
neuro disease
What kind of neurologic disease does listeriosis cause?
multifocal brainstem
Diffuse meningoencephalitis
What are possible sources of listeriosis?
carrier animals
rottingvegetation pastures
feed bunks
Which species has a higher case fatality rate due to listeriosis than cattle?
sheep & goats
What are common sources of contamination with listeriosis?
-decaying forage at bottom of feed bunk
-spoiled silage at end of trench silo
-rotting hay at periphery of hay stack
What toxin does listeria monocytogenes produce and what is its MOA?
listeriolysin- O- hemolysin
What C/S are seen in listeriosis?
asymmetric
-CP deficits
-head pressing
-CN deficits: V-XII
Ocular disease due to listeriosis manifesting as keratitis, conjunctivitis, uveitis manifests in what species?
cattle and horses (w/o neuro signs)
Cattle with listeriosis develop metabolic acidosis due to?
salivary bicarb losses d/t CN deficits
How is ovine progressive pneumonia (OPP) virus spread?
-ingestion of infected colostrum and milk
respiratory transmission
fecal contamination of drinking water
fomite
How is ovine progressive pneumonia (OPP) synergistic with what neoplasm?
Adenocarcinoma
What allows for OPP lentivirus to escape elimination by host immune response?
mutation of the gene encoding for envelope glycoproteins
ovine progressive pneumonia (OPP) infection establishes in what cell lineage?
monocyte or macrophage cell lines
ovine progressive pneumonia (OPP) multi-systemic diseases of adult sheep are characterized by:
-chronic progressive, debilitating pneumonia; respiratory failure
-aseptic indurative mastitis (“hard bag”)
-wasting progressive emaciation despite good appetite (“thin ewe syndrome”)
-chronic non-suppurative arthritis
What neurologic deficits are seen with ovine progressive pneumonia (OPP)?
weight loss
posterior paresis
hindlimb ataxia
stumbling
proprioceptive deficits
progressing ot paralysis & quadriplegia
**may localize to spinal cord
ovine progressive pneumonia (OPP) diagnosis
serology: AGID, ELISA, western blot
**presence of antibodies in serum= evidence of active infection
For testing and culling program for ovine progressive pneumonia (OPP), how often should testing be performed?
annual testing should be performed until two consecutive negative test results are obtained to be reasonably confident that the flock is virus free
Caprine arthritis encephalitis virus (CAEV) chronic infection is characterized by
demyelinating encephalomyelitis
arthritis
interstitial pneumonia
What are tissues of importance for Caprine arthritis encephalitis virus (CAEV) localization
synovium
mammary gland
central nervous system
What is the most common form of Caprine arthritis encephalitis virus (CAEV)?
debilitating polysynovitis-arthritis form
**as young as 6 months, but more frequently in mature goats
Caprine arthritis encephalitis virus (CAEV): leukoencaphlomyelitis form is predominately seen in which age
predominantly less than 2 year of age (2 -6 months of age especially)
What are differentials for Caprine arthritis encephalitis virus (CAEV) leukoencphalomyelitis form
head or spinal trauma
listeriosis
cerebrospinal nedmatodiasis (parelaphostrongylus tenuis)
multisystemic infection with mycoplasma spp
How to ddx Caprine arthritis encephalitis virus (CAEV) from listeriosis?
CAEV multifocal CNS lesions
Listeriosis generally restricted to brain stem
Caprine arthritis encephalitis virus (CAEV) differentiating from mycoplasmal infections
mycoplasmal infections typically affect kids from 1 to 6 months of age, affected animals are systemically ill and often display septic polyarthritis and polyserositis
how to differentiate Caprine arthritis encephalitis virus (CAEV) from verminous meningoencephalomyelitis?
serologic or PCR testing for the virus
CSF analysis
season
geogrpahic disturbtion of white-tailed deer host
What are ddx for Caprine arthritis encephalitis virus (CAEV) chronic interstitial pneumonia form?
lung worms, pulmonary abscessation and chronic bronchopneumonia
What is the diagnostic for Caprine arthritis encephalitis virus (CAEV)?
ELISA– whole virus, core or enveloped proteins
PCR- milk, tissue blood
AGID– older test, but still official USDA test
Caprine arthritis encephalitis virus (CAEV)L: CSF tap
TNCC: 5-1800/uL; predom mononuclear
INC protein: 0-700 mg/dL, and pleocytosis
Caprine arthritis encephalitis virus (CAEV): arthrocentesis
brown to red-tinged
inc tnccc, predom mononuclear
dec protein
Which herpesvirus types are seen to cause encephalitis in cattle?
BOHV-1 and 5
BOHV-1 typically causes what?
infectious bovine rhinotracheitis– fibrinonecrotic plaques upper airway and abortions, epizootic conjunctivitis, infectious balanoposthitis or vulvovaginitis
where does persistently infected with bovine herpesvirus survive?
in nasal and tracheal mucosa
trigeminal ganglion
brain involvement seen with bovine herpesvirus is due to
centripetal spread along sensory neurons of trigeminal and olfactory nerves
BOHV encephalitis causes a nonsuppurative meningoencephalitis widely distributed in:
grey matter of brain
** primarily cerebrum and thalamus
What C/S are seen with BOHV encephalitis?
**resp signs proceed or concurrent with neuro C/S
depression
head pressing
aimless circling
paralysis fo tongue
head tilt
nystagmus
convulsions
blindness
coma
death seizures
CSF analysis with BOHV encephalitis
mononuclear pleocytosis
ovine encephalomyelitis– louping ill epidemiology
ssRNA virus
neurotropic
Flavivrus
How is ovine encephalomyelitis– louping ill transmitted?
Ixodes ricrumus, I. persulacatus
Rhipacephalus appendiculatus
fomites (blood contaminated)
blood products
ovine encephalomyelitis– louping ill amplication occurs in what species?
wild animals and red grouse (ingesting tick), hare– improtant virus source
ovine encephalomyelitis– louping ill concomittent infection with what increases viremia and mortality
anaplasma phagocytophilum
What C/S are seen with ovine encephalomyelitis– louping ill?
ataxia, CP deficits, head tremors, hypometria (**characteristic bunny hopping gait), hyperexcitability
**progression to head pressing, recumbency, convulsions, coma, death
Diagnosis of ovine encephalomyelitis– louping ill
hemagglutination inhibition
complement fixation
**peak viremia at 7 days
**usu not viremia at time of CNS
What is the cause of hairy shaker lambs?
border disease virus
– pestivirus, noncytpathic togavirus
What is the major reservoir for border disease virus?
congenitally infected
seronegative animals with no symptoms
–> placenta, infected offspring, saliva, resp secretions, urine & feces
hypomyelination caused by ovine encephalomyelitis– louping ill
dyspmelinogenesis: virus induced degenr. of oligodroglial cells
ovine encephalomyelitis– louping ill viral immunosuppression is due to
depressed blastogenic activity of lymphs
– dec T helper cell function
– INC T suppressor cell function
ovine encephalomyelitis– louping ill cause of immunosuppression leads to death via
parasitism
diarrhea
bronchopneumonia
The worst clinical signs of ovine encephalomyelitis– louping ill are seen in which age lambs?
lambs infected in early gestation (<50 days)
ovine encephalomyelitis– louping ill: affected lambs show what C/S
short thickened body
shortened legs
smaller orbital size
doming fronta bone
+/- arthrogyropsis
+/- neuro signs
teratogenic effect of ovine encephalomyelitis– louping ill is seen at what days of gestation
50 to 90 days
ovine encephalomyelitis– louping ill causes what clinical signs in goats??
during pregnancy– fetal mummification and abortion
cattle co-mingling with sheep can contract what disease and develop what clinical signs?
ovine encephalomyelitis– louping ill
** abortions in cattle at 50 days gestation
What are differentials for ovine encephalomyelitis– louping ill?
other causes of infectious abortion
copper def (sway back)
hydrancephaly: cache valley, blue tongue, schmallenberg virus
Bovine spongiform encephalopathy (“Mad Cow”) disease cause
accumulation abnormal prion protein in CNS leading to progressive neuro disease
**altered conformation PrP-BSE
How Bovine spongiform encephalopathy (“Mad Cow”) spread?
foodborne disease of cattle
–assoc with ingestoin of meat & bone meal contam with BSE prion
typical Bovine spongiform encephalopathy (“Mad Cow”) is seen in what age cattle?
4 to 6 year old
Bovine spongiform encephalopathy (“Mad Cow”) is diagnosed with the startle reaction test with what clinical signs
hand test (punching towards animals head)/flash light/ hand clap/ loud “metallic” bang
–> BSE cattle do not habituate to startling
What are C/S seen with Bovine spongiform encephalopathy (“Mad Cow”)
inc head rubbing/head tossing
mm fasciculations
excessive vocalization
tremors/ataxia
licking of nostrils
yawning
flehman response
head butting
restlessness
How is Bovine spongiform encephalopathy (“Mad Cow”) diagnosed?
PM exam only
rapid prion tests: western blot, paraffin imbedded tissue blot, ELISA
HISTOPATH:t issue of choice: medulla obex
–>intraneuronal vacuolation in sp brain areas accompanied/ preceded by accumulation of Prp-BSE
What are differentials for Bovine spongiform encephalopathy (“Mad Cow”)?
viral encephalopathies: pseudorabies/rabies, bronaencephalitis, bovine immunodef virus encephalitis
-listeriosis
-polioencephalomalacia
-lead poisoning
-CNS parasitic migration
-brain tumors/abscesses
-vit A deficiency
Suspected cases of Bovine spongiform encephalopathy (“Mad Cow”) should be disposed of by which methods?
alkaline hydrolysis tissue digester
Bovine spongiform encephalopathy (“Mad Cow”) is linked to what human disease?
Creutzfeldt Jakob Disease
What is the prion disease of sheep called?
Scrapie
When does most scrapie transmission occur?
during breeding season
-placentas
-birth fluids
**most likely oral transmission
What are clinical signs of scrapie?
ocular lesions
aural hematoms
scratch reflex
bruxism
pytalism
apathy
hypermetria
tremors
ataxia
What are differentials for scrapie?
pseudorabies
rabies
borna encephalitis
listeriosis
PEM
Lead poisoning
CSF nematodiasis
bran tumors/abscess
maedivisni
vit A def
metabolic imbalances