Bovine Respiratory Disease: Importance and Causes Flashcards
List the 6 features of the bovine lung which make it ‘poorly designed’
- Small lung volume for body size
- Large dead space
- No collateral ventilation in alveoli
- Alveoli are easy to damage and difficult to recover
- Vasoconstriction or arteries and arterioles
- Poorly developed fibrinolytic systems
Describe the marginating structures of the lungs in cows - and where the window of auscultation is
- Triceps cranially
- Attachment of the ribs to the vertebral column dorsally
- An imaginary line joining the point of the elbow with the eleventh intercostal space.
What are the issues of having a large dead space?
- Limited respiratory reserve
- Reduced phagocytic activity in the dead space
- Decreased clearance of the bacteria
No collateral ventilation of alveoli in bovine lungs means which structures aren’t present?
No “pores of Kohn” or bronchiole anastomoses
Describe Pores of Kohn and their function
Function as collateral ventilation; if the lung is partially deflated, ventilation can occur to some extent through these pores. They equalize the pressure in adjacent alveoli and play important role in prevention of collapse of lung
How will a lung with collapse/atelectasis appear on PME?
Lung wont float and will be discoloured
What is the importance of vasoconstriction of arteries and arterioles in the bovine lung?
- Thick muscular arterioles/arteries in bovine lung
- Early vasoconstriction in pneumonia which is intended to maintain arterial BP
- BUT…this cuts off blood supply to the pneumonic lung
What is the importance of poorly developed fibrinolytic systems in bovine lungs?
Persistent fibrinous exudate
Lung scarring
How does failure of passive transfer occur?
Colostrum: too little, too late, too poor quality
How is failure of passive transfer measured?
Plasma TP < 56g/l (5.6g/dl)
Serum TP < 52g/l (5.2g/dl)
How can local host defences be reduced in lung disease/conditions?
- URT mucociliary carpet - Damaged by inappropriate air quality
- LRT inflammatory cells - Immunosuppression
List the consequences of poorly designed bovine lung and reduced host defences in respiratory disease in cows
- Death
- Poor growth
- Drug costs
- Delay in age at first calving
- Reduction in subsequent milk yield
- Prevention definitely better than cure
List the 4 viral causative agents of bovine respiratory disease
RSV (Bovine respiratory syncytial virus)
PI3 (Parainfluenza)
IBR (infectious bovine rhinotracheitis – herpes virus. Carriers common)
BVD (bovine viral diarrhoea)
List the non-viral causative agents of bovine respiratory disease
Pasteurella, Mannheimia, Histophilus, Truperella
Mycoplasma
Dictyocaulus viviparous – lungworm
How is respiratory disease in cattle influenced by the environment?
- Pathogen multiplier effects
- Seasonal effects
- Temperature and humidity