Respiratory Infections in Cattle and Sheep

Question 1

Which two cattle viruses belong in the family paramyxoviridae?

Answer 1

• Bovine respiratory syncytial virus

- Parainfluenza virus 3

Question 2

Bovine viral Diarrhoea belongs to which family?

Answer 2

Flaviviridae

Question 3

Which 4 viruses make up the bovine respiratory disease complex?

Answer 3

• Bovine respiratory syncytial virus
• Parainfluenza virus 3
• Bovine herpes virus 1
• Bovine viral diarrhoea

Question 4

What are virulence factors?

Answer 4

The components of the virus that allow it to attach to and invade host cells, i.e. they are molecules produced by the virus that allow the pathogen to cause disease

Question 5

What are the 2 main virulence factors for bovine respiratory syncytial virus?

Answer 5

G-protein

F-protein

Question 6

What are the functions of the G and F proteins?

Answer 6

G-protein - allows attachment of the virion to the host cell membrane
F-protein - facilitates fusion of the virion with the host cell membrane

Question 7

Describe the disease caused by bovine respiratory syncytial virus

Answer 7

• Interstitial pneumonia (inflammation of the tissues supporting the lung)
• Interstitial emphysema
• Secondary bacterial bronchopneumonia

Question 8

How does bovine respiratory syncytial virus predispose to secondary bacterial bronchopneumonia?

Answer 8

• Formation of multinucleated giant cells
• These contain eosinophilic inclusion bodies
• Causes obstruction of airways and impairs lung clearance mechanisms
• > predisposing to secondary bacterial bronchopneumonia

Question 9

What is a giant cell and what does it indicate?

Answer 9

A fusion of macrophages

Indicated chronic inflammation

Question 10

How does bovine respiratory syncytial virus appear grossly?

Answer 10

Filled sacs on the lung surface which would pop if touched caused by coalescence of alveoli (Alveoli septae thickened by lymphocytes and mononuclear cells)

Question 11

What are inclusion bodies?

Answer 11

Aggregates of viral capsid proteins

Question 12

How does bovine parainfluenza virus type 3 affect the airways?

Answer 12

• Bronchitis
• Bronchiolitis
• Intracytoplasmic inclusion bodies in lungs days 5-7
• Hyperplasia= proliferation in numbers of alveolar cells (clogging of airways)

Question 13

Describe how the virus of Bovine Rhinotracheitis BHV-1 infects the body and causes disease?

Answer 13

• The virus remains latent in sciatic and trigeminal nerves
• Once an animal is infected, it’s infected for life
• Initial response to infection is always by cell mediated immunity
• In times of stress, when immunosuppression occurs, you get recrudescence of disease, even in adult cattle

Question 14

What is the source of infection of Bovine Rhinotracheitis BHV-1 ?

Answer 14

Periodic shedding of persistently infected animals

Question 15

Cattle of which age are most susceptible to Bovine Rhinotracheitis BHV-1 ?

Answer 15

6-18 months old

Question 16

Describe the pathology of Bovine Rhinotracheitis BHV-1

Answer 16

• Sloughing of epithelial cells in the Upper Resp Tract

- Necrosis leaves animal open to bacterial infection

Question 17

What are the outcomes of bovine viral diarrhoea infection in each pregnancy trimester?

Answer 17

1st = reproductive losses
2nd = production of a persistently infected calf 
3rd = foetus can fight off the virus

Question 18

How does bovine viral diarrhoea attack the body?

Answer 18

• Destroys alveolar macrophages
• Depletes lymphoid tissue
• Can increase the prevalence or severity of bovine respiratory disease

Question 19

What are the 2 predilection sites for bovine viral diarrhoea?

Answer 19

palatine tonsil and the nasal mucosa

Question 20

Once bovine viral diarrhoea virus has spread in the blood, which tissues does it have a preference for, where it can be found in its highest concentrations?

Answer 20

Preference for lymphoid tissue, reaching its highest concentrations in the tonsil, thymus and ileum

Question 21

Which disease occurs as a manifestation of BVD?

Answer 21

Mucosal disease

Question 22

Which 2 sheep viruses are associated with respiratory disease?

Answer 22

• Ovine pulmonary adenocarcinoma

- Maedi

Question 23

Which cells are targeted by Ovine pulmonary adenocarcinoma?

Answer 23

Type II pneumocytes

Question 24

What is the diagnostic test for Ovine pulmonary adenocarcinoma?

Answer 24

The “wheelbarrow test” i.e. lift the sheep by its back legs like a wheelbarrow, and the fluid, which is produced from the tumour cells, comes out

Question 25

Which cells are targeted by maedi virus?

Answer 25

Monocytes

Question 26

How is Maedi virus transmitted?

Answer 26

By infected colostrum and milk as well as the respiratory route

Question 27

'Shipping fever' is caused by which bacteria?

Answer 27

Mannheimia haemolytica

Question 28

Mannheimia haemolytica occurs secondarily to?

Answer 28

Infectious bovine Rhinotracheitis (BHV-1)

Question 29

How does Mannheimia haemolytica affect the lung?

Answer 29

- Haemorrhage is a classic feature | - Thrombosis, necrosis, inflammatory cell infiltration in Mannheimia haemolytica pneumonia

Question 30

If Histophilus somni is found in the body, where is it commensal and where is it pathogenic?

Answer 30

Commensal in the genital tract and pathogenic in the respiratory tract

Question 31

What are the effects of Histophilus somni in the body?

Answer 31

- Thrombus formation - Vasoconstriction and increased epithelial permeability due to histamine release - Systemic spread

Question 32

What are the 4 main consequences of systemic spread of Histophilus somni?

Answer 32

Pleuritis Pericarditis Myocardial abscesses Joint inflammation

Question 33

Which 2 cattle bacterial are normal commensals of the URT but not the LRT?

Answer 33

Mannheimia haemolytica and Pasteurella

Question 34

Why is used to treat mycoplasma and why?

Answer 34

- No cell wall - Cannot be treated with penicillins or other beta-lactam antibiotics that target cell wall synthesis - Use oxytetracycline or macrolides

Question 35

How can animals become infected with mycoplasma?

Answer 35

Via the respiratory tract, the teat canal or genital tract | Artificial insemination with infected semen is another common route

Question 36

What are the 4 clinical signs/conditions caused by Mycoplsma?

Answer 36

- Cuffing pneumonia - Septic arthritis - Otitis media - Mastitis

Question 37

What is cuffing pneumonia?

Answer 37

Peribronchial thickening or bronchial wall thickening - A radiologic sign which occurs when excess fluid or mucus build-up in the small airway passages of the lung causes localized patches of atelectasis (lung collapse).

Question 38

Describe how Mycoplasma bovis infects the body

Answer 38

- Found in URT and LRT - Can survive in epithelial and inflammatory cells - Infected cattle shed the mycoplasma via the respiratory tract for many months and even years acting as reservoirs of infection

Question 39

How does spread of respiratory viruses occur? What can make them spread at a faster rate?

Answer 39

Close contact Carriers- age mixing Poor ventilation Poor immunity

Question 40

How can spread of disease be prevented?

Answer 40

``` Hygiene Stocking densities Correct air flow Dry environment Vaccination (where possible) ```