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Enzootic Pneumonia of Calves |  |
| Enzootic pneumonia of calves refers to infectious respiratory disease in calves. The term “viral pneumonia of calves” is sometimes used but is not preferred based on the current understanding of etiology and pathogenesis. Enzootic pneumonia is primarily a problem in calves <6 mo old with peak occurrence from 2-10 wk, but may be seen in calves up to 1 yr of age. It is more common in dairy than in beef calves and
is a common problem in veal calves. It is also more common in housed calves than those raised outside. Peak incidence of disease may coincide with decline of passively acquired immunity. Morbidity rates may approach 100%; case fatality rates vary but can reach 20%. |
| Etiology: |
| The etiology is similar to that for BRD complex in general (see
Bovine Respiratory Disease Complex: Overview). The pathogenesis involves stress and possibly an initial respiratory viral infection followed by a secondary bacterial infection of the lower respiratory tract. Stress results from environmental and management factors, including inadequate ventilation, continually adding calves to an established group, crowding, and nutritional factors such as poor-quality milk replacers. Partial or complete failure of passive transfer of maternal antibodies
is an important host factor related to development of disease. Any of several viruses may be involved, and a variety of bacteria may be recovered from affected calves. Mycoplasmal and bacterial agents including
Pasteurella
multocida
,
Mannheimia
haemolytica
, and
Mycoplasma
bovis
represent the most frequently isolated pathogenic organisms. The individual viral and bacterial etiologies, clinical signs, lesions, and treatment are discussed under viral respiratory tract infections (
Viral Respiratory Tract Infections: Overview) and bacterial pneumonia (
Bacterial Pneumonia: Overview). |
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| Control and Prevention: |
| When calves of varying ages are placed in communal pens, control of enzootic pneumonia is difficult. The severity of the pneumonia may be decreased by improved husbandry, proper housing, adequate ventilation, and good nursing care. Prevention begins with vaccinating the cows against specific respiratory viruses and bacteria 3-4 wk prepartum to improve the quality of colostral antibodies. Calves should receive good quality colostrum at 8-10% of body wt in the first 12 hr after
birth. Newborn dairy calves should be housed individually in hutches or stalls and fed whole milk or a high-quality milk replacer with a fiber content of <0.25% until 8-12 wk old. Calves should be vaccinated against respiratory viruses 3-4 wk before the first grouping, although in some situations, the presence of passive immunity may interfere with an active immune response. Calves should be of similar age when assembled into groups and the group should be limited to ≤10. As
calves mature, groups can become larger as the size of the herd, facilities, and available labor dictate. An “all in/all out” management style should be practiced when establishing and terminating a group. At minimum, newly purchased calves should be isolated before introduction to an existing group. Newborn beef calves and their dams should be moved from concentrated calving areas as soon as the calf is nursing well and is strong enough to travel. |
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