CNS disease in cattle Flashcards
What does hyperaethetic mean
Hyper responsive to stimuli
What does obtundation mean
No response to normal stimuli levels
What does stupor mean
Respond only to painful stimuli
What does coma mean
No reponse to ANY stimuli
Two spots where we can take a CSF tap
Cisterna magna and lumbosacral space
How does lesion affect limb responses based on position
When cranial to limb get hyperactive reflexes (+ataxia and weakness)
When level with limb = depressed reflexes + ataxia and weakness
When caudal to limb = no effect on limb
What clinical signs do forebrain lesions give
seizures, behavioural changes, propulsive pacing, circling, aggression, charging, mania, excessive licking
What clinical sign does cerebral disorders give
apparent blindness; but still have normal pupillary light reflex
What is hydrocephalus and what might the cause be
Congenital condition where calves are born with domed forehead
- May relate to VIt A deficiency, Schmallenberg
What is hydrancephaly; and what might have caused it
‘Dummy syndrome’ in calves; born without brain hemispheres in skull
- Due to viral infection in utero; BVDv, bluetongue, Schmallenberg
What in utero viral infection is most associated with cerebellar hypoplasia (intention tremors, ataxia, dymetria)
Bovine viral diarrhoea virus
[Also bluetongue]
What brain inflammatory condition can bull rings be associated with
Pituitary infections
When we get embolic spread of from distant abscesses/septicaemia to brain what form abscesses; what organism do we commonly isolate from it
Trueperella
What does listeriosis in calves look like
Facial cranial nerve deficits; drooped ear/eyelids, strabismus, nystagmus, loss of sensation
> On PM see microabscesses in pons and medulla
What might be a common route of brain infection with listeria in calves
Via oral route (from low quality silage); via cuts in mouth e.g due to cheek teeth
What are notifiable neurological diseases
Rabies (classical)
Aujesky’s diseases = pseudorabies/mad itch = a pig herpes virus
BSE
Bluetongue
What is the causative agent in thromboembolic meningoencephalitis
Histophilus somni
> NB respiratory disease more common than neurological
What brain condition can lack of thiamine cause in cattle
Cerebrocortical necrosis
What is an unusual finding in cerebrocortical necrosis (from thiamine deficiency)
Cut surface of the brain fluoresces
How might we treat lead poisoning
Rumenotomy to remove lead material
Chelation therapy i.e using calcium EDTA
What brain condition can salt poisoning cause
Cerebral oedema
How might a cow suffering from cerebrocortical necrosis present
Recumbant and comatose
Cortical blindness, paddling movements, head pressing, nystagmus etc
What is nervous ketosis
= neurological manifestation of ketosis; see high excitability, apparent blindness, head pressing
Treat via IV glucose
What is ‘night blindness’ a sign of
Vitamin A deficiency
In what vitamin deficiency might we see retinal bleeding
Vitamin A
What is hepatic encephalopathy
Where we see changes in behaviour and seizures in cows; because diffuse liver damage has cause hyperammonaemia and other toxic factor accumulation
Signs of botulism in cattle; and what is common source of contamination
> Flaccid paralysis, sternal recumbency, hind limb ataxia, loss of tail tone
Associated with contamination of feed with dead rodents or the use of poultry with chicken carcasses in it as manure
In what situations might we see tetanus in cattle
With deep, anaerobic puncture wounds e.g from castration or dehorning
Or ruminal damage from fibrous feeds
Which viral diseases can cause cerebellar hypoplasia in neonates
Bovine viral diarrhoea virus
Bluetongue virus
Schmallenberg virus
What diet change would encourage more thiaminase producing ruminal bacteria and therefore more risk of cerebrocoritcal necrosis
High carbohydrate diet
Why does thiamine deficiency lead to cerebrocortical necrosis
Because it is a co-enzyme in carbohydrate metabolism
- SO deficiency leads to lower glucose
-> NEURONS NEED GLUCOSE
Without energy in brain: get failure of Na+ and H2O transport; get cerebrocortical oedema, raised intracranial pressure, lower blood flow and necrosis
How does lead poisoning cause cerebral lesions
Because lead binds to sulfhydryl groups on enzymes, including those involved in carbohydrate metabolism
- Get fall in energy metabolism + effects on endothelial cells
Oedema and raised ICP –> lower blood flow and ischaemia
Why do we see cerebro-cortical necrosis (distribution) in thiamine deficiency
Because these are the neurons which are most susceptible to energy impairment so die first
Which bacteria is classically associated with haematogenous spread to brain and infectious thrombo-embolic meningoencephalitis
Histophilus somni
How does listeria reach the brain
Ascneding infection via nerves
What is typical histopathology for viral encephalitis
Perivascular cuffing with lymphocytes
Vasculitis
Cell death
Lesions usually diffuse
What rare CNS condition can neospora caninum cause in cattle
Degeneration of the spinal cord; following in utero infection
Why might cattle get a thiamine (B1) deficiency
- Low intake
- Rumen producing thiaminases; high carb diet causes overgrowth of gram +ve bacteria so more thiaminase producing ones
- Ingestion of thiaminases e.g bracken
- anti-thiamine drugs
Risk factors: sudden diet change, high grain intake, excess sulfur
What mechanism does thiamine deficiency cause CCN
Thiamine is a co-enzyme in carbohydrate metabolism; so defieicny causes failure in glucose metabolism which neurons rely on
Therefore low energy in neurons; failure of Na+ and water transport causing intracellular oedema and raised ICP
What mechanism does lead toxicity cause neurological signs
Lead binds to and stops enzymes in carbohydrate metabolism working properly
Get failure of energy metabolism + impact on endothelial cells in BBB
So get oedema and raised ICP similar to with CCN causing decreased blood flow and ischaemia
Which different agents cause which type of inflammatory response
Bacteria; mostly neutrophils
Viruses; lymphocytes
Parasites; eosinophils
