Porcine Neurology

Question 1

You go to a farm where a pig is having fits? What do you ask?

Answer 1

1. Type of farrm, location of sick pigs on farm
2. Age and number of affected pigs
3. Number of deaths
4. Length of time with clinical signs
5. Response to treatment
6. Conditions of shed - water, temperature, ventilation
7. Additives in feed

• Walk-through of the farm - assess staff, pen equipment, feed, water - get a feel of the farm
• Clinical exam of pigs - neuro eam (depending on conciousness of pig)
• PM of 2 or 3 pigs - on farm, often no gross lesions, swab brain stem for strep, culture half brain for virus
• Serum from 10 pigs

Question 2

Neuro exam continued…

Answer 2

• cerebral lesions - altered metnal state, depression, hyperaesthesia
• cerebellar lesions - intention tremors, dysmetria, high stepping gait
• vestibular lesions - otitis media, head tilt, circling, rolling
• UMN lesions - spatial positoning limbs, exaggerated reflexes, increased extensor tone
• LMN lesions - reduced muscle tone and muscle atrophy, reflex absent
• spinal cord lesion - tail bite injury
• Skin sensitivity test - conscious response indicates spinal cord and peripheral sensory nerves intact
• panniculus test - not useful in older pigs
• pedal withdrawal - exaggerated response - UMN, reduced response - LMN
• patellar reflex - sedated pigs only!

Question 3

Other diagnostic tests:

Answer 3

Proprioception:

• usually only possible in piglets - UMN lesions
• wheelbarrow test

CSF:

• lumbar puncture (lumbosacral space) - under GA, complex!

Serology

PM

NOTIFIABLE DISEASES? Aujesky’s, Teschen’s dx, Classical Swine Fever (CSF) - consider particularly if there are a lot of dead pigs.

Question 4

PIGLETS - differentials

Answer 4

1. Bacterial meningitis - streptococcus
2. Viral infections - Aujesky’s, Techen, CSF
3. Congenital tremors - may recover with nursing
4. Carbon monoxide poisoning - heating devices

Question 5

Differential Diagnosis - GROWING PIGS

Answer 5

1. Streptococcal meningitis*
2. Water deprivation *
3. Oedema dx
4. Aujesky’s dx
5. Teschen dx (eneroviruses)
6. Poisonings

* most common

Question 6

Streptococcal Meningitis

Answer 6

• Universal problem
• Streptococcs suis types 1, 2 and 14
• strep also causes arthritis, serositis
• Most common diagnosis on PM (70%)
• Survives on surfaces
• ZOONOTIC

Question 8

Streptococcus suis type 1

Answer 8

• carried in tonsils of carrier sows and enters piglets through tonsilar crypts
• most common in piglets 10-14 days
• clinical signs - pyrexia, sudden death, swollen joints, convulsions, nystagmus
• diagnosis
  
  • culture from PME and CS

Treatment:

• 3-5 days penicillin, TMS
• NSAIDs
• poor prognosis if meningitis - consider euthanasia

Prevention:

• hygiene farrowing
• prophylactic antibiotics?
• depop-repop if severe

Question 9

Streptococcus suis type II and 14

Answer 9

• ZOONOTIC (abrasions/oropharynx)
• can survive in environment for several days
• usually seen in growing pigs 3-7 days after stresses e.g. moving groups
• sudden death, pyrexia, acute arthritis, meningitis
• Diagnosis - CS and PME
• Treatment - same as type I
• Control - hygiene, prophylactic ABs, depop, repop

Question 10

Water deprivation/ salt poisoning

Answer 10

• Common
• high salt diets (rare) or rapid rehydration following water deprivation (common)
• when water becomes available, enters the brain causing cerebral oedema and raised ICP
• Clinical signs
  
  • recumbency, convulsions, atazxia, DOG SITTING, agitated
• Diagnosis:
  
  • CS and PME (eosinophilic meningitis)
• Treatment:
  
  • slow rehydration, poor prognosis
• Control:
  
  • adequate water supplies and warning systems for failure
  • frozen pipes!
  • water in medication - might put too many chemicals in affecting palatability

*suspect if lots of cystitis cases!

Question 11

Oedema Disease

Answer 11

• Re-emerging, global
• E. coli VT (verotoxigenic) - O138, O139, O141
• 7-10 days after weaning
• Sudden death, swollen eyelids, ataxia, recumbency, depression
• change in Squeak! - laryngeal oedema - high pitched
• Not a brain infection - intestinal infection
• E.coli - F18 fimbriae - produce shiga-like vero toxins - VTe or STe
• Vasoactive toxaemia and vascular damage causes gelatinous oedema

Diagnosis:

• culture VTEC from intestine
• Look for eyelid oedema
• stomach wall oedema (greater curvature)
• diarrhoea post-wean colibacillosis is more common

Prevention:

• Abs (neomycin) in feed and water after weaning
• zinc oxide in feed controls E.coli toxins
• govenment have stopped the use of zinc oxide but oedema dx on the rise again

Question 12

Aujeszky’s Disease - pseudorabies

Answer 12

• Herpes virus
• Eradicated from Britain, 2010 in Ireland
• Globally common, but excellent vaccines
• Many sick pigs, rapid spread around farm
• NOT confied to pigs - cattle, dogs, sheep
• NOTIFIABLE
• Encephalitis in piglets - incoordination, spasms, paddling
• High mortality
• outbreaks may involve pigs up to 14 weeks old
• Older pigs - locomotion changes e.g. goose stepping, run nose on floor, rabid biting, odd posture
• Also might see rhinitis and tonsillitis (PME), pneumonia common
• Diagnosis:
  
  • ​serology, histology, virology
• Excellent vaccine now available

*see tonsillar necrosis attached.

Question 13

Porcine Teschen Virus Disease

Answer 13

• Common in eastern EU
• Rare in UK
• NOTIFIABLE
• Enterovirus - mostly subclinical
• Proliferate in intestine, viral encephalitis
• Piglets <2weeks old
• Ataxia, paralysis, paddling, tremors, deaths
• NO GROSS LESIONS
• Diagnosis:
  
  • ​brain histology and virology
  • serology - paired samples

Question 14

Congenital Tremor

Answer 14

• Sporadic dx seen in piglets, tremors and shaking of the muscles
• might die from not being able to suckle
• Hypomyelinogenesis and muscle tremor
• Piglets may appear normal, clinical signs by 3 days
• Classified into 4 groups depending on brain histology

Question 15

Group 1

Answer 15

• Associated with a classical swine fever

Question 16

Group 2

Answer 16

• Associated with circovirus involving both circovirus types 1 and 2 simultaneously. most of the problems in the field are in group 2

Question 17

Group 3 and 4

Answer 17

• Associated with either hereditary disorders seen in landrace and saddleback breeds or with organophosphorous poisoning.

Group 4 includes Aujesky’s dx and Japanese encephalomyelitis virus.

Question 18

Hypoglycaemia

Answer 18

• very common mortality in newborn piglets
• low blood glucose due to inadequate milk intake
• little fat reserves so become hypoglycaemic quickly
• CS - weakness, ataxia, hypothermia, fitting, opisthotonus, champing jaws
• Diagnosis:
  
  • ​CS, blood glucose <2.8mmol/L
• Treatment:
  
  • ​15ml 20% glucose solution IP q4-6 hours

Question 19

Other differentials

Answer 19

• Spinal abscess
• toxicities -selenium
• Nutritional deficiency - vitamin A, Pantothenic acid