Pathology and Microbiology of Respiratory Infections - Pigs

Question 1

Bacteria

Answer 1

Bordetella/Pasteurella
Actinobacillus
Haemophilus
Mycoplasmas

Question 2

viruses

Answer 2

Porcine reproductive and respiratory syndrome virus (PRRSV)
Swine influenza
Aujeszky’s disease
Porcine circovirus

Question 3

atrophic rhinitis

Answer 3

Combination of early colonisation of N/P with Bordetella bronchiseptica + Pasteurella multocida producing the osteolytic toxin.
malformation of snout

Question 4

Bordetella bronchiseptica dermonecrotic toxin

Answer 4

Damages osteoblasts prevents bone growth

turbinate atrophy

Question 5

Pasteurella multocida osteolytic toxin

Answer 5

Stimulates osteoclasts turbinate - bone resorbtion

atrophic rhinitis

Question 6

contagious pleuropneumonia

Answer 6

Actinobacillus pleuropneumoniae
Acute or chronic fibrinohaemorrhagic pneumonia with pleurisy
worldwide distribution
high morbidity + mortality
Initial outbreaks very severe progresses to chronic status with sporadic cases.
Subclinical carriers & recovered carriers

Question 7

Pathology of contagious pleuropneumonia in pigs

Answer 7

Fibrinonecrotic bronchopneumonia with pleuritis
Spreads throughout all lung lobes: - cranioventral distribution may not be evident
Pleural adhesions form in chronic cases

Question 8

Actinobacillus pleuropneumoniae

Answer 8

NAD-dependent (growth on chocolate agar) Waxy, sticky colonies Delicate, Gram-negative
15 serotypes
Pathogenicity: - Apx toxins, Capsule polysaccharide, Takes iron from porcine transferrin
Apx toxins are RTX protein toxins, cytolytic, haemolytic
?stimulate massive cytokine release - pulmonary inflammation, haemorrhage, oedema

Question 9

actinobacillus suis

Answer 9

Pleuropneumonia-like disease (mild) in high health-status animals.

Question 10

haemophilus parasuis

Answer 10

Glassers disease - polyserositis

Fibrinous exudate in high health-status animals

Question 11

Pathology of Haemophilus parasuis infection in pigs (Glasser’s disease)

Answer 11

suppurative bronchopneumonia
polyserositis (pleuritis, pericarditis and peritonitis), meningitis and polyarthritis
lesions may be present singly or combination
mortality high in young animals
predisposing factors include stress (mixing, weaning + adverse environmental conditions)

Question 12

mycoplasma hypopneumoniae

Answer 12

enzootic pneumonia (EP) in the pig
widespread and very common
predisposition to other respiratory diseases
transmission by aerosol coughing resolves
vaccine effective

Question 13

Pathology of mycoplasmal infections

Answer 13

usually chronic, non-fatal disease unless secondary infection present
seen commonly at slaughter
reduced growth rate and coughing
Gross - cranioventral consolidation and red/grey discolouration
Microscopic features - similar to ‘cuffing pneumonia’ in calves

Question 14

Porcine reproductive and respiratory syndrome virus (PRRS)

Answer 14

Infection of URT, systemic spread in macrophages
May cause respiratory signs - interstitial pneumonia but frequently subclinical
May predispose to or enhance effects of infection with other viruses or bacteria

Question 15

swine influenza

Answer 15

Sudden outbreaks of respiratory disease with barking cough and respiratory distress in naïve herds
Bronchiolitis and pneumonia
If endemic in herd, weaned pigs will develop clinical signs as soon as levels of maternal antibodies decline
no vaccine in UK

Question 16

swine influenza - clinical signs

Answer 16

diarrhoea
coughing
sore throat
lethargy
loss of appetite
sneezing
mucous nose/eyes
fever
weight loss
poor growth

Question 17

Pseudorabies (Aujeszky’s disease)

Answer 17

Porcine herpesvirus
Sneezing, coughing, laboured breathing, fever and weight loss.
CNS disease in piglets; abortion, stillbirth, mummified foetuses in sows

Question 18

Pseudorabies (Aujeszky’s disease) - control

Answer 18

Endemic in Northern Ireland (and Republic) but has been eradicated from rest of UK
Vaccination only permitted in Northern Ireland

Question 19

porcine circovirus

Answer 19

Considered to be immune suppressive and to predispose pigs to other infections
Possible involvement in porcine respiratory disease complex, post weaning multisystemic wasting syndrome (PMWS), porcine dermatitis + nephropathy syndrome (PDNS) = PCAD
Two vaccines available in UK