Farm Animal Neurological Disease Flashcards
How would you conduct a neurological exam of a farm animal?
Head: behaviour, mentation, head posture Cranial nerves Neck, trunk and limbs: reflexes Tail, anus, bladder: tone and sensatiion Gait: paresis, ataxia, lameness, dysmetria
What are the major groups of cortical disease in farm animals?
Cerebrocortical necrosis Viral Parastitic TSE Trauma/abscesses/meningitis/tumours
What are the main groups of neurological disease in farm animals?
Cortical disease Brainstem and cranial nerves Cerebellar disease Metabolic disease Spinal cord and peripheral nerve disorders Neuromuscular diseases
What is cerebrocortical necrosis (CCN)?
Also known as polioencephalomalacia (PEN), seen in ruminants and pseudoruminants. It has multiple aetiologies all leading to necrosis of the grey matter of the brain:
THIAMINE metabolism
SULPHUR metabolism.
How does altered thiamine metabolism cause CCN?
Thiamine is a cofactor for transketolase in pentose phosphate pathway, providing glucose for the brain
Less transketolase
So increased lactate, pyuvate etc
Intraneuronal swelling through decreased ATP/Na/H2o activity
Increased intracranial pressure and necrosis
What causes altered thiamine metabolism and thus CCN in farm animals?
Thiamine storage is poor. Excessive grain intake or sudden change in feed promotes thiaminase producing bacteria.
Deficient pastures, unsupplemented
Thiaminase producing plants spp. - Bracken
How does sulphur metabolism cause CCN?
Sulphur found in beef cattle feed as sulphur, sulphate and gypsum
Sulphate reduced to sulphide and ultimately incorporated into crude protein and energy released
Sulphides are neurotoxic (inhibit cytochrome C oxidase, preventing ATP production)
What are the clinical signs of CCN?
Sudden death or recumbency Blindness Stargazing Miosis Strabismus Head tilt
What is the treatment for CCN?
Thiamine IM or SQ
Dexamethasone to reduce cerebral oedema
Diazepam to control seizures
What are the main viral diseases causing neurological issues in farm animals?
Maedi Visna - Sheep
Caprine arthritis-encephalitis virus - Goats
Border disease - Sheep
BVD - Cattle
What are the clinical signs of caprine arthritis encephalitis virus?
Ataxia Paresis Head tilt Nystagmus Decreased PLR Usually young goats Enlarged joints, shifting lameness, weight loss, ill thrift
How is caprine arthritis encephalitis virus spread?
Aerosol, milk, colostrum, transplacental
How can you test for caprine arthritis encephalitis virus?
Ab ELISA
How do you treat caprine arthritis encephalitis virus?
Test and cull
Explain Borders Disease pathogenesis…
Infects naive ewe in pregnancy
Abortion, infertility or deformities
Lambs infected in first half of gestation become immunotolerent and remain viraemic - PI
Similar to BVDv
What are the clinical signs of Borders Disease?
CNS, skin and skeletal systems
Skin: steel wool coat, hyperpigmentation
Skeletal: short legs, domed forehead, small orbits
CNS: ataxia, tremors, hops on rear legs.
CNS usually disappear after 20 days.
How do you test for borders disease?
Antibody testing young sheep for flock status
Virus testing to find PIS
What are the neurological signs of BVD?
Hydrocephalus Cerebellar hypoplasia Head tremors Weak Proprioceptive deficits Ataxia Blindness Strabismus Often die
What parasitic disease cause neurological disease in farm animals?
Ovine encephelomyelitis (Louping ill)
Coenurosis (Taenia)
Coccidosis (Eimeria)
Sarcocystis
What are the clinical signs, epidemiology and treatment of louping ill?
CS: Fever, depression, muscle tremors, hypermetria, bunny hopping gait, coma
Epi: Yearling sheep, spring, weeks after place on infected pasture
Tx: Supportive
What are the clinical signs, epidemiology and treatment of Coenurosis (sheep gid)?
CS: Spaceoccupying lesion, ataxia, unilateral vision loss, head tilti, circling
Epi: Adult worm shed in dog/cat faeces, ingested on pasutres, eggs hatch in SI and migrate to CNS via blood
Tx: Praziquantel
What are the clinical signs, epidemiology and treatment of sarcocystis?
CS: ataxia, weakness, tremors, hyperexcitable, seizures
Epi: Mostly asymptomatic, large numbers needed
Tx: Diclazuril
What are the clinical signs, epidemiology and treatment of nervous coccidiosis?
CS: GI signs then depression, ataxia, hyperaesthesia, seizures
Epi: neurotoxin from parasite. High mortality rate
Tx: Diclazuril
Describe that pathogenesis of TSE…
Slowly progressing fatal infectious notifiable disease. Accumulations of prion proteins in the CNS depost as amyloid plaques within nervous tissue
