Resp disease in farmed calves Flashcards
1
Q
Agents that cause calf pneumonia: viruses, bacteria and mycoplasma?
A
- Viruses (act as primary pathogen)
- Infectious Bovine Rhinotracheitis (IBR)
- Respiratory Syncytial Virus (RSV) (important)
- Parainfluenza Virus III (PI3) (important)
- Bovine Viral Diarrhoea Virus (BVD)
- Bacteria (generally secondary)
- Mannheimia haemolytica (“Transit or shipping fever”) (can be a primary cause of pneumonia)
- Stress acts as a trigger factor and get invasion of the lungs with this pathogen with shipping fever.
- Pasteurella multocida
- Mannheimia haemolytica (“Transit or shipping fever”) (can be a primary cause of pneumonia)
- Mycoplasmas (URT signs generally, but it also causes otitis, so will be a sign that this is involved).
- Mycoplasma dispar
- Mycoplasma bovis
- Ureaplasma spp.
2
Q
Clinical signs generally seen with calf pneumonia?
A
- nasal discharge
- Often ocular discharge - serous then muco-serous nasal discharge.
- Depression
- Extension of head and neck to assist respiration
- Coughing
- Elbows abducted
3
Q
Treatment of calf pneumonia?
A
- Two cornerstone treatments for calf pneumonia: antibiotics and anti-inflammatories.
- Antibiotics
- Used to treat primary bacterial / mycoplasmal causes
- If suspect these are the primary cause.
- Used to prevent secondary infection if initial viral cause (more common)
- Treat secondary infection if already established
- Used to treat primary bacterial / mycoplasmal causes
- Anti-inflammatories
- Reduce inflammation (limit lung damage and consolidation), improve demeanour – antipyrexic
- NSAIDs or steroids
- NSAIDs generally preferred.
- Other treatments
- e.g. antihistamines, sympathomimetics, Xanthine derivatives, expectorants
- Whilst all are theoretically useful, none are widely used
- Clenbuterol has a farm animal license for uterine relaxation, so could use off label here.
- e.g. antihistamines, sympathomimetics, Xanthine derivatives, expectorants
4
Q
How do you chose the correct antibiotic for calf pneumonia?
A
- Rational to use ABs as bacterial complications are incredibly common with calf pneumonia.
- Spectrum of activity
- Broad spectrum, including mycosplasmal activity, required
- Broad is best choice.
- If signs of otitis media, need to use an AB that covers mycoplasma.
- Duration of action
- Long duration reduces / prevents necessity to re-handle
- Handling to treat can be stressful, esp. beef animals. Using longer acting would be best.
- Bacteriostatic / cidal
- Cidal preferred, especially if steroids used as the anti-inflammatory
- If using steroids, use cidal, but practically probably doesn’t make much a difference and most that are licensed are static.
- Resistance
- Oxytetracyline is a good choice, although resistance has emerged.
- Cost
- Newer, long acting products can be expensive
- But avoid need to handle, so have welfare and health benefits, as well as reducing staff time.
- Practice policy
- In reality, choices will be driven by practice policy. But must feel comfortable that this is appropriate.
- Responsible use
- Safety
- Tilmicosin (“Micotil”) self injection is potentially fatal in man. Now licensed only for use by veterinary surgeons. Farmers cannot give it.
- Hence, don’t really use it.
- Spectrum: florfenicol, tulathromycin, tildiprosin, gamithromycin, oxytet all some activity against mycoplasmae and histophilus
- Only Draxxin licensed against mycoplasma, widespread myc resistance to oxytet and some to florfenicol
5
Q
Explain tetracyclines
A
- Oxytetracycline
- Variety of brand names
- Cheap
- i/m, repeat after 48-72 hours if necessary
- Consider this choice with beef animals!
- Original calf pneumonia antibiotic. However, means quite a lot of resistance now.
- Some long acting versions (2-3days), so even if you use 72hrs, you will have to repeat at least once.
6
Q
Explain chloramphenicol derivatives
A
- Florfenicol
- Combination product (AB+NSAID) also available (“Resflor”)
- e.g. “Nuflor” and many others
- Big dose volume
- 1ml/15Kg i/m (2x with 48 hr gap) or2ml/15Kg s/c (single dose)
- It is unsyringable – very thick and viscous, so slow to inject.
- Widely used.
7
Q
Explain Macrolides
A
- Really commonly used - long duration of activity
- Tilmicosin
- e.g. “Micotil” and others
- S/C. Licence states a single dose
- CARE potentially fatal: vet administration only
- Original one used – can kill you.
- Tulathromycin
- “Draxxin”
- S/C. Up to 10d duration from single dose
- License against mycoplasma
- Tildiprosin
- “Zuprevo”
- S/C. Very long duration from single dose
- Gamithromycin
- “Zactran” - an azalide (similar to macrolides)
- Single S/C injection, claimed duration of up to 15 days
8
Q
Explain Fluroquinolones
A
Don’t last a long time, but can give a high dose.
- Marbofloxacin
- e.g. “Marbocyl Solo” and others
- Single i/m injection
- Danofloxacin
- e.g. “Advocin 180”
- S/C. Repeat after 48 hours if necessary
- Enrofloxacin
- e.g. “Baytril Max” and others
- S/C. Licence states a single dose
9
Q
Anti-inflammatory choices for calf pneumonia
A
- 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
- Reduce consolidation, lots have a license for this dz.
- Steroids
- Reduce inflammation, although broadly immunosuppressive if treatment prolonged
- Dexamethasone is licensed for use in cattle
- Much less commonly used as NSAIDs work well and people concerned about immunosuppressive side effects.
10
Q
Pros and cons of treating sick animals only
A
- 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
- Can increase total cost
- Bacterial lung damage only treated, not prevented
11
Q
Pros and cons of treating sick and pyrexic animals
A
- Isolate sick animals (if possible) and treat
- Additionally, isolate and treat all animals with a temperature =/>39.5oC (Antibiotics +/- anti-inflammatories)
- Pros
- Cost of antibiotic restricted
- (Still!) responsible use of antibiotics (as you are treating a clinical disease)
- Protects animals early in course of disease against bacterial damage
- If doing this, ones that are sick – give AB and NSAIDs, those just with high temp – can just give NSAIDs if no other symptoms.
- Cons
- Increased time (cost) to take temperatures
- May be offset by decreased meds cost
- Increased time (cost) to take temperatures
12
Q
Pros and cons of treating all animals if prevelance of disease is greater than the threshold
A
- 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) ßknown as metaphylaxis
- Pros
- Protects animals early in course of disease against bacterial damage
- May help prevent disease ifprimary pathogen bacterial/ mycoplasmal
- Cons
- Expensive (meds cost plus time)
- Less responsible use of antibiotics (Tx of healthy animals)
- Arbitrary choice of proportion (30%)
- Shouldn’t use this option.
13
Q
Pros and cons of prophylactic treatment
A
- 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
- However, this is rare that the primary cause is bacterial.
- 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
14
Q
Risk factors for calf pneumonia
A
- Prevention is a balance between infection pressures and calf defences.
- Infection pressure
- 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 can also shed and act as source of infection.
- Other affected calves
- Environment
- Calf defences
- Immune status
- Inadequate passive transfer (make sure colostrum transfer is good).
- Decline in MDA
- Stress
- Weaning, transport, castration/disbudding, mixing groups etc
- Concurrent disease (e.g. BVD)
- Nutrition
- Inadequate nutrition
- Deficiencies
- Weaning
- Immune status
- A complex multi-factorialdisease.
- Risk factors combine to an overall “infection pressure” or “weight of infection”
- The importance (or weight) of each risk factor will vary between farms
- Changing one factor can sufficiently alter the balance and make clinical disease either more or less likely
- Sudden or small change in one factor can lead to outbreaks of disease
15
Q
Prevention of calf pneumonia
A
- Preventing pneumonia relies on shifting the balance away from disease
- This can be achieved in a number of ways:
- 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
- In reality will look at both sides and look at where the main risk factors are.
