Respiratory disease in calves

RespiRatoRy disease in calves is an interaction between:
• Various infectious agents (whether bacterial, viral or both)
• environment (poorly
buildings, overcrowding)
• immunity (vaccination status)

Viral Causes
the important viral causes of
respiratory disease in calves are:
• infectiousbovinerhinotracheitis(iBR)
• Bovine respiratory syncytial virus
(BRsV)
• parainfluenza-3 virus
• Bovine virus diarrhoea virus (BVD)
may be involved in some herds.

Bacterial Causes
the important bacterial causes of
respiratory disease are:
• Mannheimia haemolytica
• pasteurella multocida
• Haemophilus somni
• Mycoplasma bovis
the first two organisms are often still collectively termed “pasteurellae” and the disease “pasteurellosis”.Economic implications
Respiratory disease is estimated to cost the UK cattle industry more than £60 million annually.
• Financial losses result from antibiotic treatment and labour costs
• £50 for mild cases to £800 when the animal dies
• Weight loss during illness can affect a large proportion of the group

Clinical signs
Clinical signs during an outbreak of respiratory disease in a group of calves can be very variable but the first cattle affected often show the most severe signs. the clinical signs include:
• elevated rectal temperature (above 39.6°c)
• increased respiratory rate
• increased respiratory effort
• Frequent coughing
• Muco-purulent ocular/nasal discharge
• Lethargy
• Not eating
• Lying down more than usual
elevated rectal temperature is the most reliable clinical feature of respiratory disease in calves and may detect disease 24 hours before onset of more severe clinical signs. in an outbreak rectal temperatures should be taken at least once daily and if feasible twice daily.

Diagnosis
Diagnosis of viral infection may involve:
• ocular and nasal swabs
• Collection of lung fluid (broncho-alveolar lavage)
• Collection of blood samples two weeks apart
• post mortem examination is only useful in cases of sudden death
Antibiotic treatment
the choice of antibiotic, and possible non-steroidal anti-inflammatory drug treatment is based upon:
• Veterinary advice and knowledge of previous outbreaks of respiratory disease on the unit.

Recurrence of bacterial infections is common (up to 25 per cent) often necessitating repeat antibiotic treatments 5-14 days later.

this situation is caused by re-infection of the physically damaged respiratory tract. While antibiotic treatment of the whole group of calves is practised in some situations this often results in 2- 4-fold increase in treatment costs because up 25 to 75 per cent of the calves are injected unnecessarily because they would not have succumbed to disease.

Prevention/control
Vaccination
there are a number of vaccines to control respiratory disease and veterinary advice should be sought for the most appropriate prevention strategy as part of your veterinary health plan.

Control of respiratory disease is likely to be best achieved by attention to all of the following:
• General husbandry practices especially the ventilation system
• Correctly-timed administration of vaccines
• Reducing stocking density
• stressful events such as disbudding, dehorning and castration are best undertaken before housing or delayed until calves have been housed for at least six weeks.
Main points of building design:
• air enters below the eaves and exits at the ridge
(natural or stack effect whereby spent warm air
rises to the ridge out to be replaced by fresh air
drawn in from below the eaves)
• Minimum of six air changes per hour on a still day
air should appear fresh and free of ammonia or slurry smells when you walk through the shed especially during still winter nights

• the ridge opening should be 300mm (minimum) with a cap at least 150mm above

• Buildings should not exceed 20m width. Multispan buildings should be avoided
• Minimum airspace allowances 10 cubic metres for calves up to 90kgs

• Upturned corrugated sheeting on roof with a 25mm gap
• spaced boarding all round building including gable ends (Netlon polypropylene mesh also popular)

• ensure adequate drainage to prevent high humidity. Condensation on underside of roof and cobwebs over outlets are indicators of poor ventilation.

DISEASE CONTROL AND PREVENTION SHOULD BE PART OF YOUR VETERINARY HEALTH PLAN – CONSULT YOUR VET.

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