Small Ruminants: Neurological Disease of Sheep Flashcards
What specific history should be taken when investigating neurological disease?
What is done after a history?
- Age group
- Number affected
- Speed of onset
- Speed of progression
- Time of year
- Feeding
Full clinical exam
Followed by a neurological exam
What are the common clinical signs of cerbellum disease?
What are the differentials?
- Altered head carriage
- Balance- ataxia, wide stance, dysmetria (high steps)
- Intention tremour- incl nystagmus
- Not common
DDXs- Congenital (cerebellar hypoplasia), border disease (cerebellar hypoplasia), possible abscess
What are the clinical signs of diffuse cerebrum disease?
What are some DDxs?
- Altered mental state- depressed, hyperexitable, disorientated
- Blindness
- Seizures
- Opisthotonos- recumbent, extended front legs, flexed hind legs
DDxs- Bacterial meningitis, cerebrocortical necrosis, pregnancy toxaemia
What are the clinical signs of local cerebrum disease?
What are some DDxs?
- Controlateral blindness
- Circling
- Proprioceptive defecits
DDXs- GID cysts, brain abscess, trauma
What are the clinical signs of vestibular disease?
- Head tilt to affected side
- Loss of balance
- Circling
- Falling/rolling to one side
- Spontaneous nystagmus
- Middle ear infection
- Unulateral facial paralysis (runs close to middle ear)
- What can cause brain stem disease?
- What are the clinical signs?
- Listeriosis
- Depression because of ascending reticular activation system
- Multiple cranial nerve defects- V, VII, VIII
- Ipsilateral hemiparesis
- What are the clinical signs of spinal cord disease?
- What can cause it?
1)
* No signs of central disease
* Depends on spinal cord site: tetraparesis/paraparesis
Proprioception
Pain
Skin sensitisation
Pedal and other spinal reflex
2) Spinal abscess, joint ill, tick pyaemia, wobblers syndrome, trauma, congenital abnormality
What are common neurological diseases of younf lambs <3 months?
- Border disease- tremors, hairy shakers
- Congenital swayback- ataxia, copper deficiency
- Drunken lamb disease and lamb nephrosis- ataxia, depression
- Bacterial meningitis- collapsed
- Tetanus
- Trauma
- Spinal abscess (joint ill)
- Listeriosis- circling, facial nerve paralysis
- Louping ill
How can spinal abscesses (joint ill) be treated in lambs?
1mg/kg dextamethasone, penicillin
5 days at least
- What are the ‘variable signs’ of louping ill?
- What disease is it important in?
- Head pressing, trembling, tremors, nystagmus, lip twitching, louping gait
- Important in grouse- high mortality
Vaccine available- bought in, naive
- What is CCN?
- What causes it?
- How and when does it present?
- What history may predipsose?
- What are the clinical signs?
- Cerebrocortical necrosis
- Vitamin B1 deficiency- thiamine
- Acute onset in growing lambs >3m
- Diet change or worming- thiaminase production in the rumen
- Dull, disorientated, blind, tremors, recumbency, opisthotonos, convulsions
- How is CCN treated?
- How is it diagnosed?
- How is it prevented?
1)
* Vitamin B1 IV slowly 10mg/kg
* Vitamin B1 IM every 12 hours for 3 days
* House quietly
* Vision should return 5-7 days
2) PM of the brain
3) Prevention- diet changes
- What causes listeriosis?
- What is it associated with?
- Why are 18-24 month olds more commonly infected?
- How does it progress?
- Listeria monocytogenes
- Associated with poorly preserved silage- soil contaminated- mold
- Changing molar teeth allowing infection of buccal tissues
- Ascending infection to the brain
- What are the clinical signs of listeriosis?
- How is it diagnosed?
- How is it treated?
- Anorexia, depression, unilateral hemiparesis, trigeminal nerve paralysis, facial nerve paralysis, drooped ear, lowered eyelid, deviated muzzle, loss of blink
- CS, CSF tap, PM
- Supportive care- remove silage
Good if caught early
Gold standard- 75kg ewe, 6g benzylpenicillin, 20ml procaine penicillin, 1mg dexamethasone, 5ml procaine penicillin for 5 days
- What parasite causes Gid?
- How does it present?
- What is the treatment?
- How can it be controlled?
- Taenia multiceps
- Gradual onset- circling, unilateral blindness, head tilt, skull softening
- Surgical precise- cerebral (good prognosis), cerebellar (poor prognosis)
- Worm dogs every 6 weeks with praziquantel- keep away from sheep carcasses
What is commonly misdiagnosed as listeriosis?
Vestibular disease
- What is vestibular disease associated with?
- What agents commonly cause it?
- What are the clinical signs?
- What is the treatment?
- Associated with otitis media and ascending infeciton from pharynx to eustachian tube
- Pasturella, streptococcus, truperella pyogenes
- Loss of balance, head tilt to affected side, horizontal nystagmus, aural discharge, facial nerve paralysis
- 5 days penicillin
What neurological diseases are common in adult sheep?
- Cervical sub-luxation
- Gid
- Listeriosis
- Brain abscess
- Louping ill
- Trauma
- Metabolic disease- toxaemia, hypocal
- Scrapie
- Wobbler texels
What are the likely causes of a collapsed recumbent ewe at lambing time?
- Pregnancy toxaemia- Diagnosis BOBH blood levels, treatment propylene glycol (poor prognosis unless early)
- Hypocalcaemia- before lambing, stress factors, 20-40ml 20% borogluconate
- Septicaemic listeriosis- hopless prognosis
- When is hypomagnesia seen?
- How does it usually present
- How is itr treated?
- Seen after lambing- milk drain, stress
- Sudden death usually- recumbant, convulsive
- IV Ca and Mg slowly or Mg SC- prevention high mg concentrates
What are the two different types of scrapie?
Classical- infectious, neurological, fatal chronic progressive
Atypical- prion disease
What are the TSEs possible in sheep?
BSE
CJD
Atypical scrapie
What are the features of a prion disease?
- Very resistant to heat, disinfectants, UV
- Causes abnormal protein to accumulate in the brain- neurological dysfunction
- Spead to mother of offspring
- Hoziontal- birth fluids
What are the clinical signs of Scrapie?
- Progressive fatal neurological disease- long inc
- 2-5 years old
- Single animal
- Neurological
- Altered mental state- exitable, nervous, depressed, trembling, ataxia, recumbency
- Skin- prutitis, rubbing, scratching, wool loss
- Weight loss
- Death
NOTIFIABLE
What is the statutory Scrapie testing scheme?
Testing Scheme
* The UK is required to test annually for TSE:
– 10000 fallen sheep aged over 18 months;
– 500 fallen goats aged over 18 months;
– 10000 sheep slaughtered for human consumption; and
– Sheep and goats from scrapie-infected flocks and herds.
– Carcases for the fallen sheep and goat surveys are randomly selected for sampling at relevant animal by-products plants, based on quotas provided by AHVLA. Samples are also taken during routine inspections by AHVLA.
* TSE Feed Controls
* The feed controls are the key animal health control for BSE. It is illegal to feed animal protein to ruminants (egcattle, sheep and goats) and the feeding of processed animal protein to all farmed animals, although there are exceptions.
* SRM Controls at abattoirs
– Specified Risk Material Removed from Sheep over 6 months old and Incinerated
-brain, spinal cord and spleen
