Bovine Respiratory Disease Complex

Question 1

What are the 3 strains of bovine herpes virus and what disease do they cause?

Answer 1

BHV1 - respiratory disease and abortion
BHV2 - infectious pustular vulvovaginitis
BHV4 - metritis

Question 2

At what age do you see BHV1 causing clinical signs of respiratory infection in calves?

Answer 2

6 months to 2yo

Question 3

At what stage of gestation does BVD cause foetal absorption and abortion?

Answer 3

1st trimester 0-95 days

Question 4

At what stage of gestation does BVD create persistently infected animals?

Answer 4

95-120 days

Question 5

At what stage of gestation does BVD cause congenital lesions, a seropositive foetus or abortion due to placentitis?

Answer 5

120-285days 3rd trimester

Question 6

What congenital lesions does BVD cause?

Answer 6

Cerebellum hypoplasia
Micropthalmus
Cataracts

Question 7

What causes BVD mucosal disease and what are clinical signs?

Answer 7

Persistently infected animal becomes infected with a cytopathic biotype

CS: oral ulceration, ill thrift, diarrhoea, respiratory disease due to immunosuppression

Question 8

How can you diagnose BVD?

Answer 8

Bulk milk tank testing
Ear notch tissue test - when calf is tagged at 9w
Check 5 blood ELISAs per group

Question 9

How can you control BVD?

Answer 9

Vaccination before first breeding
Test bought in animals
Test Bulls blood and semen
Biosecurity
Test and cull PIs

Question 10

What are the components of the bovine respiratory disease complex?

Answer 10

1. Bovine herpes virus 1 - infectious bovine rhinotracheitis
2. Parainfluenza virus 3 - flavivirus
3. Bovine viral diarrhoea - pestivirus
4. Respiratory syncitial virus - pneumovirus

Question 11

What are the gross lesions associated with Respiratory Syncitial Virus on PM?

Answer 11

Emphysematous lungs
Multinucleate giant cells
Air bullae
Alveoli have clumped together

Question 12

What are the post mortem findings with IBR (BHV1)?

Answer 12

Necrosis of the tracheal mucosa

Question 13

What is the pathogenesis of BVD leading to respiratory disease?

Answer 13

Immunosuppression makes PIs more susceptible to respiratory disease

• destruction of alveolar macrophages
• depleted lymphoid tissues

Question 14

What bacterial agents commonly cause respiratory disease in cattle?

Answer 14

1. Mycoplasma bovis
2. Pasturella
   
   • Mannheimia haemolytica
   • Pasteurella multocida
   • Histophilus somni

Question 15

What should you treat mycoplasma infections with?

Answer 15

Oxytetracyclines or macrolides

Target DNA synthesis - no cell wall

Question 16

What other diseases can mycoplasma bovis cause?

Answer 16

Septic arthritis (joint ill) - calves
Otitis media
Mastitis 
Conjunctivitis 
Pneumonia 

Only significant if found the in the LRT - commensual in the URT

Question 17

What are the typical post mortem lesions associated with mycoplasma?

Answer 17

Cuffing pneumonia - lymphocyte cuffing around bronchioles

Cranioventral atelectasis

Question 18

What aetiological agents are responsible for Shipping Fever?

Answer 18

IBR (BHV1) followed by Mannheimia haemolytica

Question 19

What presentations does Histophilus somni cause?

Answer 19

Myocardial abscesses 
Pleuritis
Pericarditis 
Arthritis 
Thrombomeningoencephalitis

Question 20

How can you treat Histophilus somni?

Answer 20

Usually too late - acutely fatal

Question 21

How can you prevent bovine respiratory disease?

Answer 21

4L colostrum in 1st 6h, another 4L in the next 6
Improving housing and husbandry
- reduce SD, improve hygiene and ventilation
Vaccination increases herd immunity

Question 22

What aetiological agents can you vaccinate against?

Answer 22

IBR only - Rispoval
BVD + IBR - Bovillis
BVD only - Bovella

Question 23

Why are cows so susceptible to respiratory disease?

Answer 23

1. Small lung volume
2. Large respiratory dead space
3. Alveoli easy to damage and difficult to recover
4. No collaterals ventilation of the alveoli
5. Early and substantial vasoconstriction of arteries and arterioles
6. Persistent fibrinous exudate and lung scarring

Question 24

What is the cost of calf pneumonia?

Answer 24

Death
Poor growth
Delayed age at first calving
Drugs costs
Reduction in subsequent milk yield 
Other disease

Question 25

What defines failure of passive transfer?

Answer 25

Plasma proteins <56g/L

Serum proteins <52g/L

Question 26

What are predisposing factors to respiratory disease?

Answer 26

Bad air quality - ammonia, too dry / humid, too cold
Immunosuppression - SARA, BVD, stress eg weaning / disbudding
Overstocking and large group sizes
Larger than a 2 week spread between age groups

Most common during the housing period in winter

Question 27

What are the similarity and differences between PI3 and RSV?

Answer 27

PI3 - Young calves
RSV - calves and older calves

Lower respiratory tract infections - classic viral pneumonia

Can vaccinate both

Question 28

What are two viruses that causes lower respiratory tract disease?

Answer 28

PI3

RSV

Question 29

What type of respiratory disease does BHV1 cause?

Answer 29

Upper respiratory tract infection

Ocular and nasal discharge, Pyrexia, milk drop

Question 30

How do animals present with secondary pasteurellosis?

Answer 30

Following a stressful incident - shipping fever

Acute dysponea and septicaemia

Question 31

What are the lower critical temperatures for calves in different conditions?

Answer 31

0c - no draught
9c - draughty
15c - wet floor