Neurological Disease In Sheep Flashcards
What questions should be asked when gathering the history for a neurological case?
- Age group
- Number affected
- Speed of onset
- Speed of progression
- Time of year
- Feeding
Once the history has been gathered what are the next steps in a neurological case?
Full clinical exam
Neurological exam
If the cerebrum is affected the stage of disease correlates with?
The severity of the signs
What are some signs you would see which would correlate with a diffuse cerebral lesion?
- Altered mental state i.e. depressed, disorientated, hyperexcitable
- Blindness
- Seizures
- Opisthotonus
What is Opisthotonus?
D dramatic abnormal posture due to spastic contraction of the extensor muscles of the neck, trunk, and lower extremities that produces a severe backward arching from neck to heel
* Recumbant
* Extended front legs flexed hind legs
Name 3 example causes of a diffuse cerebral lesion
- Bacterial meningitis
- Cerebrocortical necrosis
- Pregnancy toxaemia
What signs would you see that would correlate with a local cerebral lesion?
- Contralateral blindness
- Circling
- Proprioceptive deficits
Name 3 example causes of a localised cerebral lesion
- GID cysts (coenuris cerebralis, Taenia multiceps)
- Brain abscess
- Trauma
What signs would you see that would correlate with a cerebellar lesion?
- Altered head carriage
- Balance: ataxic, but not weak
- Wide stance
- Dysmetria
- Intention tremor including nystagmus
What is a congenital cause of a cerebellar lesion?
Cerebellar hypoplasia
What is an infectious case of cerebellar lesions?
Border disease
- Cerebellar hypoplasia
What signs would you see that would correlate with a lesion of the vestibular system?
- Head tilt towards the affected side
- Loss of balance
- Circling
- Falling/rolling to one side
- Spontaneous nystagmus
- Middle ear infection
- Unilateral facial nerve paralysis
Which condition leads to lesions in the brainstem?
Listeriosis
What signs would you see that would correlate with a brainstem lesion?
- Depression
- Multiple cranial nerve deficits
- Ipsilateral hemiparesis
What signs would you see that would correlate with a spinal lesion?
- No signs of central disease
- Depends on site of spinal cord
- Tetraparesis/ paraparesis
- Proprioception
- Skin sensation
- Pain
What are some possible causes of spinal lesions?
- Trauma
- Congenital abnormality
- Spinal abscess e.g. joint ill tick pyaemia
- Wobblers syndrome in Texel’s
List some possible causes of neurological diseases that could affect lambs from 0-3months old (9 possible)
- Border disease
- Congenital swayback (copper deficiency)
- Drunken lamb disease
- Bacterial meningitis
- Spinal abscess
- Listeriosis
- Louping ill
- Tetanus
- Trauma
How would a lamb with bacterial meningitis present?
Collapsed
If a lamb was circling with facial paralysis which disease would be indicated?
Listeriosis
Which neurological disease of young lambs is tick borne?
Louping ill
What are the clinical signs of louping ill?
- Head pressing
- Trembling & tremors
- Nystagmus
- Lip twitching etc
- “louping gait”
List some possible causes of neurological diseases that could affect lambs from 3+ months
- Cerebrocortical necrosis
- Listeriosis
- GID
- Louping ill
- Trauma
What is the cause of cerebro-cortical necrosis?
Vitamin B1 (thiamine) deficiency
What is a likely history for an animal with cerebro-cortical necrosis?
Diet change or worming
Thiaminase production in rumen
What are the clinical signs of cerebro-cortical necrosis?
- Dull
- Disorientated
- Blind
- Tremors
- Recumbency
- Opisthotonus
- Convulsions
How can cortico-cerebral necrosis be treated?
- Vitamin B1 iv (slow 10mg/kg)
- Vit B1 i/m every 12 hours For 3 days
- House quietly
- Vision should return 5- 7 days
Name the agent that cause listeriosis
Listeria monocytogenes
Listeriosis is associated with what kind of feeding?
Feeding poorly preserved silage soil that has gone mouldy
What is the pathway in the body of a listeria infection?
An ascending infection to the brainstem
What are the clinical signs of listeriosis?
- Anorexia, depression
- Unilateral hemiparesis
- Trigeminal nerve paralysis
- Facial nerve paralysis
What signs are seen with trigeminal nerve paralysis caused by listeriosis?
Salivation
Food impaction in the cheek
What signs are seen with facial nerve paralysis caused by listeriosis?
Drooped ear
Drooped lower eyelid
Deviated muzzle
Loss of blink
How would you diagnose listeriosis?
- Clinical signs
- CSF tap
- PM
How can you treat listeriosis?
- Good prognosis if caught early
- Remove silage
- Benzylpenicillin IV
- Procaine penicillin IM
- Dexamethozone IV
What is the cause of gid?
Taenia multiceps
Describe the pathogenesis of taenia multiceps
- Eggs picked up by sheep, cysts develop in brain cerebral, cerebellar (Coenoris cerebralis)
- Primary host dog
What are the clinical signs of taenia multiceps infection?
Gradual onset
Circling
Unilateral blindness (opposite to lesion)
Head tilt
Skull softening
What is the treatment and prognosis of taenia multiceps?
- Surgical
- Signs depend on site of lesion
- Cerebral – good prognosis
- Cerebellar – poor
How can flocks be controlled to manage Taenia multiceps?
- Worm dogs every 6 weeks praziquantel
- Keep away from sheep carcasses
Vestibular disease is commonly misdiagnosed as?
Listeriosis
What are the clinical signs of vestibular disease?
- Loss of balance
- Head tilt towards the affected side
- Horizontal nystagmus
- Aural discharge
- Facial nerve paralysis
How is vestibular disease treated?
5 days of penicillin
List some possible causes of neurological diseases that could affect adult sheep
- Gid cyst
- Listeriosis
- Brain abscess
- Louping ill
- Trauma
- Metabolic disease
Compare the neurological clinical signs in the following 3 metabolic diseases in adult pregnant sheep
1. Pregnancy toxaemia
2. Hypocalcaemia
3. Hypomagnesemia
- Dull, blind
- Collapsed, bloated, flaccid paralysis
- Staggers, hyperaesthesia
Define classical scrapie
- Infectious neurological disease of sheep
- Fatal chronic progressive, brain disease of sheep
Describe the aetiology of scrapie
- Causes abnormal protein to accumulate especially in brain causing neurological dysfunction
- Spread mother to offspring (vertical transmission) prenatally and colostrum and milk
- Horizontally birth fluids, placenta
- Considerable Genetic Variation in Susceptibility to Infection
What are the clinical signs of scrapie?
- Progressive Fatal Neurological disease
- Long incubation period: 2-5 years old
- Single animal
- Altered mental state excitable nervous depressed, aggressive
- Trembling
- High step ataxia
- Recumbency
- Skin prurititus, rubbing scratching, wool loss
- Weight loss
- Death
What should you do if scrapie is suspected?
Notifiable Report to AHVLA
Test animal - If positive
- Compulsory Scrapie Flocks Scheme
- Movement Restriction, Genotyping, Testing and Culling
How is pregnancy toxaemia diagnosed and treated?
Diagnosis –BOHB levels blood
Treatment – poor prognosis unless early
