Bovine Respiratory Disease (BRD)
"last update: 16 April 2024"
- Etiology and risk factors of BRD
BRD is a multifactorial disease where different causes are involved in the etiology of BRD including viruses, bacteria, parasites, malnutrition, environmental stressors, and host susceptibility.
1-Viruses commonly associated with BRD Complex are bovine herpesvirus-1 (BHV-1, IBR), bovine viral diarrhea virus (BVD), bovine respiratory syncytial virus (BRSV), parainfluenza-3 (PI-3), and bovine respiratory coronavirus (BRCV).
2-Bacteria are also associated with BRD Complex including Mannheimia haemolytica (formerly Pasteurella haemolytica), Pasteurella multocida, Mycoplasma bovis, Histophilus somni, and Trueperella pyogenes.
3-Parasites – Lungworm can cause irreversible damage to an animal’s lungs and can lead on to further respiratory disease if not treated.
4-Environmental factors
sanitation, ventilation, and overcrowding, and stress events such as weaning, transportation, vaccination, castration, and dehorning, also significantly increase the risk of developing BRD.
5- Stocking
A-Mixing Stock – Mixing bought-in stock with current stock can increase the risk of exposure to various different pneumonia-causing bacteria and viruses, which they have not encountered before and therefore have not developed an immunity to.
B- Overstocking - Can lead to stress and build-up of infection in closely stocked areas increasing the transmission of airborne pathogens.
5- Stress factors: Procedures such as weaning, castration, disbudding, TB testing, housing and transport are inevitably stressful and these will adversely affect the animals’ immune system, thus increasing their susceptibility to BRD.
List of most common viral diseases causing BRD and the characters of each of them
|
Viral cause of BRD |
Characteristic findings |
|
IBR
|
· Contagious disease affecting cattle causing severe respiratory manifestation as coughing, fever, anorexia, nasal discharge that appear serous then mucopurulent with redness of the nose and necrotic lesions of nasal mucosa. Pneumonia is developed only after secondary bacterial infection |
|
DVD
|
· Acute, infectious disease causing with bloody diarrhea, high fever, off- feed, mouth ulcers, and pneumonia. Abortion of pregnant cattle usually occurs in sporadic cases. |
|
BRSV |
· It is the major cause of bovine respiratory disease in calves during the first year of life. The virus usually causes mild respiratory disease is characterized by coughing, mucous to seropurulent nasal discharge, slight to moderate increased respiratory rates and abnormal breathing sounds. · Moderately affected calves exhibit respiratory rates above 80/min, tachypnoea, harsh lung sounds across most of the lung wall and profound coughing. Generalized symptoms range from slightly elevated rectal temperature, mild CNS depression and anorexia to high fever, deep depression, and coma.
|
|
BPI-3
|
· The virus causes mild respiratory disease of ruminants when it is the only pathogen. · In combination with other pathogenic agents, BPI3V is one of the most significant respiratory pathogens in ruminants. · This virus can cause pneumonia on its own, but it is more generally a part of the etiological complex of enzootic pneumonia. · The clinical signs in calves include fever, lacrimation, serous nasal discharge, depression, dyspnea, and coughing. Some animals may develop bronchointerstitial pneumonia that selectively affects the anteroventral portions of the lungs. · An uncomplicated bovine parainfluenza virus 3 infection runs a brief clinical course of 3–4 days that is usually followed by complete and uneventful recovery. However, stress factors predispose the calf to secondary bacterial infection, especially Mannheimia haemolytica infection. This syndrome is characterized by purulent nasal discharge, cough, rapid respiration, anorexia, fever, general malaise, and substantial mortality from acute fibrinous bronchopneumonia. |
|
BRCV |
· pneumoenteric virus that infects the upper and lower respiratory tract and intestine. It is shed in feces and nasal secretions and also infects the lung. · Bovine corona virus is the cause of 3 distinct clinical syndromes in cattle: (1) calf diarrhea, (2) winter dysentery with hemorrhagic diarrhea in adults, and (3) respiratory infections in cattle of various ages including the bovine respiratory disease complex or shipping fever of feedlot cattle |
