Respiratory Disease in Calves Flashcards
What are the common viruses causing calf pneumonia? (4)
–Infectious Bovine Rhinotracheitis (IBR)
–Respiratory Syncytial Virus (RSV)
–Parainfluenza Virus III (PI3)
–Bovine Viral Diarrhoea Virus (BVD)
Name bacteria causing pneumonia? (2)
–Mannheimia haemolytica (“Transit or shipping fever”)
–Pasteurella multocida
Name mycoplasma causing calf pneumonia (3)
–Mycoplasma dispar
–Mycoplasma bovis
–Ureaplasma spp.
What is going on here?
Fr/H calf with typical nasal discharge associated with pneumonia
Occular and serous signs
What is the issue here?
Hereford X calf demonstrating depression and extension of the head and neck to assist respiration
Detection here is at a more severe stage – possibly a rapid progression or not detected
What is this?
Consolidation of lung lobes in a calf which died of pneumonia
What are the treatment options for calf pneumonia?
•Antibiotics
–Treat bacterial / mycoplasmal pneumonia
–Prevent secondary infection if initial viral cause (as viral is often the primary issue) – reduces the potential for lung damage
–Treat secondary infection if already established
•Anti-inflammatories
–Reduce inflammation (limit lung damage), improve demeanour, anti-pyretic
–NSAIDs (preferred) or steroids
•Other treatments
–e.g. antihistamines, sympathomimetics, Xanthine derivatives, expectorants
–Clenbuterol? – licensed for repro so could use on cascade
•Whilst all are theoretically useful, none are widely used
What criteria do we need to think about when chosing antibiotics? (8)
–Spectrum of activity
•Broad spectrum, including mycosplasmal activity, required
–Duration of action
•Long duration reduces / prevents necessity to re-handle (stressful to handle)
–Bacteriostatic / cidal
•Cidal preferred, especially if steroids used as the anti-inflammatory
–Resistance
•Oxytetracyline is an good choice, although resistance has emerged
–Cost
•Newer, long acting products can be expensive
–Avoid the need to handle – health and welfare? Reduce staff time? Reduce re treating.
–Practice policy
–Responsible use
–Safety
What is the issue with using Tilmicosin (“Micotil”)?
Self injection is potentially fatal in man. Now licensed only for use by veterinary surgeons. There are many products in the same family which have he same benefits without the death risk
What antibiotics can we use for calf pneumonia? (9)
Oxytetracycline:
A) Why is there resistance now?
B) What is good about it?
C) What is the issue of it?
A) The original use of AB in cattle – so effective so was put in milk replacer or feed to prevent and this is why we have resistance to it
B) Cheap
C) i/m, repeat after 48-72 hours if necessary (care if going to slaughter not to damage meat)
What is the issue of using florenicol?
•Hard to syringe – very viscous! Hard to get out on a cold day
What is the benefit of using macrolides?
All long durations
Which macrolide can only be given by a vet?
Tilmicosin
Which classification of ABs should not really be used in farm animals?
Fluoroquinolones
Why may an animal not respond to ABs? (5)
•Remember, failure to respond does not necessarily indicate antibacterial resistance
–Viral causes
–Inflammation / lung damage persists well beyond bacterial cure
–May not have treated for long enough
–Disease may have progressed too much
•Farmers often expect a rapid response and are disappointed if this does not occur
What is the good thing of using anti-inflammatories? (2)
Nsaids? (2)
Steroids? (2)
•Anti-inflammatories
–An excellent adjunctive therapy, esp. in badly affected animals
–Reduce inflammation (limit lung damage), improve demeanour
•…NSAIDs
–Antipyretic, anti-inflammatory and analgesic
–Many NSAIDs have a licence for respiratory disease
•…Steroids
–Reduce inflammation, although broadly immunosuppressive if treatment prolonged
–Dexamethasone is licensed for use in cattle
What are the 3 treatment strategies with calf pneumonia?
- Treat sick animals only
- Treat sick and pyrexic animals
- Treat all animals if prevalence exceeds a threshold value
How does “treating sick animals only” work?
What are the pros? (2)
What are the cons? (3)
–Isolate sick animals (if possible) and treat
–Watch group carefully, isolate and treat as necessary
Pros -
- Cost of antibiotic minimised
- Responsible use of antibiotics
Cons:
- “Chase” the outbreak although this is rare unless it is bacterial
- Can increase total cost
- Bacterial lung damage only treated, not prevented
How does Treating sick and pyrexic animals work?
A) What are the pros? (3)
B) What are the cons? (2)
–Isolate sick animals (if possible) and treat
–Additionally, isolate and treat all animals with a temperature =/>39.5oC (Antibiotics +/- anti-inflammatories)
–Could treat the obvious sick with AB and NSAID and those pyrexic treat NSAID and keep and eye on all temperatures
Pros:
- Cost of antibiotic restricted
- (Still!) responsible use of antibiotics
- Protects animals early in course of disease against bacterial damage
Cons:
- Increased time (cost) to take temperatures
- May be offset by decreased meds cost
How does the strategy Treat all animals if prevalence of disease > threshold (e.g. >30% affected) work?
What are the pros? (2)
What are the cons? (3)
–If a high proportion of the group are already sick, many other will be in the early stages or likely to succumb. (Often ABs only to non-clinicals)
Pros:
- Protects animals early in course of disease against bacterial damage
- May help prevent disease if primary pathogen bacterial/ mycoplasmal
Cons:
- Expensive (meds cost plus time)
- Less responsible use of antibiotics (Tx of healthy animals)
- Arbitrary choice of proportion (30%)
How does prophylactic treatment work?
A) What is the pro?
B) What are the cons? (2)
•Antibiotic treatment of the whole group, timed before a known risk. Common examples includes movement and housing
Pros:
–May help prevent disease if primary pathogen is bacterial / mycoplasmal
Cons:
–Expensive (cost of medicine and time to administer)
–Some consider this entirely inappropriate antibiotic treatment of healthy animals
- This is probably a reasonable attitude!
- Should be able to control risk using other measures
What are the risk factors for calf pneumonia?Split into - envrionment (5), sources of infection (2), Immune status (5)
•Environment
–Overcrowding
–Inadequate ventilation
–Poor air quality
–Air spaces shared between large # calves
–Humidity
•Sources of infection
–Other affected calves
•Different sources
–Clinically normal older animals
•Immune status
–Inadequate passive transfer
–Decline in MDA
–Stress
•Weaning, transport, castration/disbudding, mixing groups etc
–Concurrent disease
–Nutrition
- Inadequate nutrition
- Deficiencies
- Weaning
How can we prevent pneumonia? (4)
–Increasing calf defences / resistance to disease
–Decreasing the number of risk factors
–Decreasing the importance (“weight”) of one or more risk factors
–Any combination of the above
