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
What can inadequte ventillation cause? (3)
–Decreased pathogen removal
–Increased temperature
–Increased humidity (& therefore pathogen survival)
What are the 2 methods of ventilation?
–Natural Ventilation
–Artificial Ventilation
What type of ventillation is this?
The “Stack” Effect
What is the stack effect?
Solid wall and then perforated wall
Avoids draughts and high air speed on their back
Needs to allow air but not rain
What is the purpose of yorkshire boarding?
Gaps between the boards allows air to flow in (and out) but prevents the entry of nearly all rain
What does this show?
The “Stack” Effect
How does the stack effect ventillation work?
- Animals within a building warm the air, which rises carrying the stale air out through ridge (or ventilation slots) in the roof
- Cool fresh air is drawn in through the sides of the building (Yorkshire boarding) ventilating it
What is this?
Capped ridge
What is this?
The “Stack” Effect:
Mono-pitch roof
Young stock – this works quite well. Half of a normal pitched roof
What factors affect ventilation? (4)
–The air inlet and outlet areas
–The height difference between inlets and outlets
–Inside and outside temperature differences
–Heat generated by animals
- Numbers
- Live weight
What does artificial ventilation involve?
Using fans to blow air or suck out
Where natural ventilation alone does not work
When are fans used for ventilation?
•Fan should only be used as a last resort and only if changes to building to achieve natural ventilation have been considered
When may artifiical ventilation be useful?
•Fans can be used to ventilate a building when natural ventilation is inadequate
–E.g. old stone / brick buildings with slate roofs (no inlets or outlets)
–Large buildings with internal “dead spots”
–A building sited in the centre of a complex without adequate inlets
Improving ventilation in (old) buildings built for other purposes and converted to hold calves can be challenging
What can we do? (4)
–Slot roof
–Slot walls
–Open up the building
–Artificial ventilation
Can we vaccinate for calf pneumonia?
•Vaccination can be extremely helpful, although it is not a panacea (cant expect to have a farm with lots of pneumonia to vaccinate and it all goes away – probably a challenge from a few aspects)
Name reasons for calf pneumonia vaccination failure (6)
–Pathogen can not be vaccinated against e.g. M. bovis
–Pathogen not in the vaccine used on the farm
–Overwhelming “weight” of infection – often the issue
–Vaccine course not completed or inappropriate
–Calf failed to respond to vaccine e.g. concurrent disease / immunosuppression
–Vaccine inactivated by poor handling / administration
Which causes of calf pneumonia is there a vaccine for?? (5)
•IBR, BVD, PI3, RSV and M. haemolytica
What are the calf pneumonia vaccine combinations? (2)What is the vaccine type? (2)
How do we give the vaccine?
- Available in both monovalent and many assorted polyvalent combinations
- Live attenuated & dead
- Intranasal (can give some really useful protection), S/C and i/m
