Enzootic Bronchopneu.
Pathogenic Agent
Feeding and watering facilities are a common source of infection
Parainfluenza 3 (PI-3), Adenovirus, REO Virus, Rhinovirus, ECBO virus, Coronavirus, (BRSV, BVD/MD)
Secondary Agents:
Pasteurella hemolytica and multocida, Staphylocci, Haemophilus somnus, Chlamydia, Mycoplasms, Corynebacteria and other.
Etiology
The cause of enzootic pneumonia in feedlot and dairy cattle appears to be a complex interaction among stressors.
Poor ventilation, excessive ammonia levels in barns, sudden nutritional changes, overcrowding, and shipment may debilitate defense mechanisms in cattle, predisposing them to infection by viruses listed above.
Often secondary bacterial agents cause severe bronchopneumonia once the virus succeeds in damaging the upper and lower airways. According to the latest research, the BRSV infection is considered to be an independent disease among the enzootic bronchopneumonia complex.
Clinical Signs
The signs of viral pneumonia infection include dry cough, fever, depression, anorexia, serous nasal and ocular discharge and dyspnea. By auscultation you will find tracheal rales and occasional rales in the lower lung fields.
Fatalities are uncommon, and recovery should occur within a week.
Secondary bacterial infections are recognized by a second increase in temperature, moist painful cough, rapid respiratory rates, open mouth breathing, severe depression, anorexia and salivation. There is a significant decrease in milk yield. Auscultation of the lungs reveals moist or dry rales in the lower lung fields of both sides. Often death occurs within a few days, especially without treatment, in cases of severe bacterial bronchopneumonia. Chronic courses are not uncommon.
Diagnosis
Infectious bovine enzootic pneumonia may be suspected from clinical signs such as fever, cough, nasal discharge, dyspnea, results of auscultation in conjunction with a history of recent transportation or arrival of bought in cattle, indoor housing and deficiencies in management. Your diagnosis can be confirmed by detection of virus in culture from nasopharyngeal swabs or tracheal wash. You can also take paired serum samples.
Differential Diagnosis
IBR, shipping fever, lungworm pneumonia, BRSV
Prevention
- Optimize housing and management conditions (e.g.quarantine, hygiene, disinfection, vector control)
- stimulate the unspecific defense mechanisms of animals at risk
- isolate new animals for at least a week and screen them for diseases
- induce and improve acquired immunity of herds by vaccination (IBR, PI-3, BVD/MD, BRSV, Pasteurella, Hemophilus somnus)
- revaccinate regularly to maintain vaccination status
- cleaning and disinfection of animal houses and transporting equipment at regular intervals helps to prevent spreading of virus
- avoid mechanical tranmission
- rodent control
- fly control
- disinfection
Treatment
Treatment should be aimed at the frequent secondary bacterial pneumonia. Initial antimicrobial therapy should be based on prior experiences with antibiotics in the herd. If the animal fails to respond within 3 days of treatment, change to broad spectrum antibiotics and select antibiotics on results of culture and sensibility tests. Symptomatic and supportive treatment includes non-steroidal anti-inflammatory drugs (NSAID), bronchodilatators, secretolytics and immunostimulating drugs.
Literature
- Blood, D.C., Radostis, O.M., Veterinary Medicine, 1989
- Dyer, R.M., The Bovine Respiratory Disease Complex: A Complex
- Interaction of Host, Environmental, and Infectious Factors, Compendium on Continuing Education Vol 4, No7, July 1982
- Hofmann, W., Rinderkrankheiten Band 1, 1992
- Fraser, C.M. et al., The Merck Veterinary Manual, 1991
- Mantey, S., Heifer Enemy No.1, Dairy Herd Management, December 1993
- Smith, B. P., Large Animal Internal Medicine, 1990