Listeriosis
- Facts (5)
- clinical syndromes (4)
- listeria monocytogenes
- widespread environmental organism
- growth inhibited in aerobic conditions/pH < 5.6
- found in silage
- feb/march
clinical syndromes
- encephalitis in yearling lambs (april/may)
- Abortion
- septicaemia
- Iritis/ ketoconjunctivitis
Listeriosis
- Pathogenesis
- CS (5)
infection through tooth cavity/buccal injuries –> gains access to cranial nerves (trigerminal) –> microabscesses in specific parts of brain –> unilateral lesions
CS
- depression and anorexia
- deviation of head/head tilt
- circling
- unilateral facial nerve paralysis
- uncoordinated gait/hemiparesis
Listeriosis
- Dx (3)
- Tx (1)
Dx:
- history and CS
- histopath
- CSF may show increase in protein and mononuclear cells
Tx:
- 1-2 weeks of ABs that penetrate the BBB (penicillin/tetracycline and increase dose/florfenicol)
Looping ill
- facts (3)
- CS
- flaviviridae
- ixodes rcinus transmission
- spring/autumn (when ticks are highest)
CS:
incoordination/ataxia –> paralysis, convulsions, coma –> death (24-48 hours)
Looping ill
- epidemiology
- control
- most adults are immune
- lambs are protected by colostral immunity
- ewe lambs retained for breeding most commonly affected in the following spring
- vaccinate 28 days before exposure to tick infested pasture
- reduce tick numbers
Polioencephalomalacia (CCN)
- Cause
- pathogenesis
- weaned lambs and adult sheep
- after dietary changes (onto concentrates) of disruption from normal feeding
-caused by a thiamine (vit B1) deficiency e.g. by overgrowth of thiaminase-producing bacteria in rumen –> altered glucose metabolism –> necrosis of superficial grey matter –> generalised cerebral oedema
Polioencephalomalacia (CCN)
- CS (5)
- DDx (5)
- Dx (2)
- Tx
CS
- blind, wandering
- stargazing
- high stepping gait
- head pressing
- progression to recumbency, backwards flexion of neck, hyperaesthesia, convulsions
DDX
- pregnancy toxaemia
- listeriosis
- focal symmetrical encephalomalacia
- acute coenurosis
- meningitis
Dx:
- CS, Hx, response to treatent
- decrease in erythrocyte transketolase and increase in thiaminase activity in faeces
Tx
-IV vit B1 and dexamethasone
Scrapie
-neurodegenerative disease caused by prions
CS:
- pruritus (nibble reflex)
- behavioural changes (nervous/excitable/aggressive)
- weight loss
- ataxia/changes in gait
Dx: PM histopath/IHC/biochemical test for PrPsc
Transmission: vertical and horizontal (urine/blood/placenta)
Scrapie control (4)
- breeding out VRQ and breeding in ARR(resistant form
- compulsory scrapie flock scheme (CSFS)
- slaughter of susceptiple genotypes and buy in resistent types of whole flock slaughter and restock with resistant sheep 3 years later
- -> second option only for goats
Coenurosis
- pathogenesis (3)
- cerebral (4)
- cerebellar (4)
- Dx
- Tx
- Px
- caused by larval stages of tapeworm taenia multiceps
- contamination of pasture by dog faeces
- oncospheres carried in blood to brain or spinal cord and develop into cysts
cerebral cysts:
- contralateral blindness
- proprioceptive deficits
- circling
- localised softening of frontal bone
cerebellar cysts
- dysmetria
- ataxia
- wide based stance
- bilateral proprioceptive deficits
Dx: Hx/CS
Tx: surgical removal of superficial cysts under GA
Px: worm farm dogs, prompt disposal of fallen stock
Sarcicystosis
- S.tenella and s. arienticanis
- obligate host sporozoan parasites
Px: prevent farm dogs eating sheep carcases, prevent faecal contamination of pastures/feed
MVV
brain form: head tilt/circling towards affected side
thoracolumbar spinal cord form: unilateral pelvic limb proprioceptive deficit/paraysis
Focal symmetrical encephalomalacia
facts (3)
CS (6)
DDx for CCN
clostridium perfingens type D
e toxin
CS:
- separation
- blindness
- anorexia
- nystagmus
- ataxia
- recumbency –> convulsions
prevent by vaccination
Hepatic encephalopathy
CS (4)
Dx (2)
CS:
- depression
- blindness
- head pressing
- teeth grinding
Dx:
- liver enzymes
- Vit B12 /Cu in blood or liver
Vestibular disease
- CS (4)
- Tx
CS:
- head tilt to affected side
- nystagums
- circling towards affected side
- facial paralysis
Tx: 5 days penicillin or trimethoprim suphonamide
