BRD 1 Flashcards
BRD (shipping fever, enzootic calf pneumonia) results in what type of pneumonia?
bronchopneumonia or pleuropneumonia
what cattle anatomy makes them more prone to resp dz?
- bovine lungs small relative to O2 requirements –> lower capacity for diffusion of O2 across air-blood barrier
- limited compliance –> abundant interstitial connective tissue
- diffusion of O2 across air/blood barrier less efficient
what environmental factors predispose cattle to resp dz?
- indoor housing
- stocking density
- inclement weather
- transportation
- nutritional deficiencies
- concurrent dz
what is the difference b/t tracheitis and expectorated material from lungs?
tracheitis: exudate adhered to mucosa and when removed, mucosa is eroded/ulcerated –> hyperaemia & edema
expectorated: easily wiped away to reveal smooth healthy tracheal mucosa
what is the role of viral pathogens in BRD?
- primary viral infections can compromise host –> precursor to immune dysfunction and allow bac t proliferation
how can viral pathogens compromise host to allow bac t proliferation? (4 things)
- damage URT mucosa/mucociliary clearance
- damage tracheal epithelial cells
- depletion/damage to innate host defence mechanisms
- suppression of acquired immune system
list the viral pathogens involved in BRD
- BVDV
- parainfluenza virus 3 (PI3)
- bovine resp syncytial virus (BRSV)
- bovine herpesvirus 1 (BHV1)
- bovine coronavirus
BVDV is ____ immunosuppressive
highly
PI3 has ____ dz. What changes this?
mild dz, unless complicated by secondary bac t agents
BRSV causes what type of pneumonia?
interstitial pneumonia
what are the C/S of BRSV?
- acute onset
- high fever
- severe dyspnea w/ open-mouthed breathing
- audible expiratory grunt
bovine herpesvirus 1 is also called what?
infectious bovine rhinotracheitis, red nose
BHV1 likes what type of cells? what does this mean?
epitheliotropism
means massive destruction of URT and tracheal epithelium (ulceration and necrosis)
what are the C/S of BHV1? what is the pathognomonic lesion?
- heavy serous nasal discharge that becomes thick and mucopurulent w/I 72 h
- may also have conjunctivitis (serous ocular discharge, followed by mucopurulent w/I 72h)
- abortions
- white plaques on nasal mucosa
diphtheritic membrane = pathognomonic
how is BHV1 transmitted?
nasal + genital secretions
true or false: bovine coronavirus is ubiquitous in cattle pops
true
what is important to know about herpesviruses?
latency!
recrudescence of viral shedding occurs w/ immunosuppression
what does bovine coronavirus cause in cattle?
broadly: pneumonia and diarrhea in calves and adults (among other things)
what is the role of bacterial pathogens in BRD?
suppression of immune system = rapid production of bac t in URT
many bac t are commensals and need that first suppression of immune system to get in there
what types of things suppress the bovine immune system in order for bac t to cause infection in BRD?
- stress
- viral infection
- parasitic infection
- ammonia fumes
list the major bacteria involved in BRD
- Mannheimia haemolytica
- Pasteurella multocida
- Histophilus somni
- Mycoplasma bovis
(Biberstinia trehalosi – virulent, fast-acting relative of M. haemolytica)
what gram are the BRD bacteria?
gram -, except for mycoplasma, which is gram +
What ABs can you use to treat BRD and why would you choose/not choose them?
- tetracyclines (>1 inj)
- pot sulpha (off label)
- amino pen (ok)
- cephalosporins (off label)
- phenicol (1 inj, broad spec)
- macrolides (10 days, but no)
- floroquin (best, but not 1st line)
how does Mannheimia haemolytica cause disease?
commensal, ability to reside in URT among other non-pathogenic strains (A2), and then converts/overgrows under stressful stimuli to a pathogenic serotype (A1)
