Dr Ingrid Lorenz
AHI CalfCare Technical Working Group‘Prevention and Management of Pneumonia in Dairy Calves’ is the latest leaflet from the CalfCare Technical Working Group of AHI, aimed at farmers, giving an introduction to the control of pneumonia. Below is an extract from the leaflet.Pneumonia in dairy calves is often referred to as a ‘multifactorial disease’. This means that, besides infectious agents, a multitude of environmental and management factors and their interactions are responsible for the outbreak of disease (Figure 1).
Apart from adequate colostrum intake and proper further nutrition, which have been discussed in this journal before, housing and ventilation play a major role in the development of calf pneumonia.
Calves are born with functional thermoregulatory mechanisms. Therefore, healthy calves are readily able to deal with outdoor temperatures as long as they receive adequate amounts of energy and are provided with a dry, well-bedded and draft-free shelter.
Many calf rearing systems can work well if managed properly. In general, outdoor housing is superior to indoor housing, and the risk for transmission of infection is lower in individually housed calves than in groups. If calves are housed in groups, the risk is lowest in small, stable groups of calves of similar age.
Inadequate ventilation of calf barns increases the risk of disease due to a build-up of high levels of humidity, noxious gases, dust and bacterial content. A thorough investigation of the ventilation, and measures of improvement as appropriate, is warranted if dairy calf pneumonia is a problem.
Early signs of calf pneumonia include elevated respiratory rate, fever, serous nasal discharge and, at the most mild, depression or inappetence. Since early treatment is the most important factor that prevents treatment failure, recognition at this stage would be preferable.
Antibiotic treatment of bacterial pneumonia must be sufficient in duration and, most crucially, early enough to prevent lesions forming that may resist both therapy and regeneration of normal lung parenchyma.
The value of diagnostic tests in calf pneumonia is limited due to the multifactorial nature of the disease and the uncertainty if the pathogens recovered from samples are causative to the disease. Most outbreaks can be successfully managed using the principles for treatment described above, and diagnostic tests cannot replace the examination of management practices and facility design in cases of recurrent outbreaks. Testing for the possible involvement of viruses can be of value for decisions on vaccination programmes.
The efficacy and economic viability of vaccination against respiratory disease in dairy calves remains uncertain. Young calves do not produce specific antibodies after vaccination in the presence of maternally derived immunity. For this reason, it is commonly believed that maternal antibodies can interfere with the efficacy of vaccination. To overcome this issue, research in recent years has focused on the use of the mucosal immune system for vaccination, and intranasal vaccines against BRSV and Bovine Herpes Virus 1 are now available.
Copies of this leaflet and other CalfCare leaflets are available for you to download for your clients from
www.animalhealthireland.ie
