BRD 1

Question 1

BRD (shipping fever, enzootic calf pneumonia) results in what type of pneumonia?

Answer 1

bronchopneumonia or pleuropneumonia

Question 2

what cattle anatomy makes them more prone to resp dz?

Answer 2

• 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

Question 3

what environmental factors predispose cattle to resp dz?

Answer 3

• indoor housing
• stocking density
• inclement weather
• transportation
• nutritional deficiencies
• concurrent dz

Question 4

what is the difference b/t tracheitis and expectorated material from lungs?

Answer 4

tracheitis: exudate adhered to mucosa and when removed, mucosa is eroded/ulcerated –> hyperaemia & edema

expectorated: easily wiped away to reveal smooth healthy tracheal mucosa

Question 5

what is the role of viral pathogens in BRD?

Answer 5

• primary viral infections can compromise host –> precursor to immune dysfunction and allow bac t proliferation

Question 6

how can viral pathogens compromise host to allow bac t proliferation? (4 things)

Answer 6

• damage URT mucosa/mucociliary clearance
• damage tracheal epithelial cells
• depletion/damage to innate host defence mechanisms
• suppression of acquired immune system

Question 7

list the viral pathogens involved in BRD

Answer 7

• BVDV
• parainfluenza virus 3 (PI3)
• bovine resp syncytial virus (BRSV)
• bovine herpesvirus 1 (BHV1)
• bovine coronavirus

Question 8

BVDV is ____ immunosuppressive

Answer 8

highly

Question 9

PI3 has ____ dz. What changes this?

Answer 9

mild dz, unless complicated by secondary bac t agents

Question 10

BRSV causes what type of pneumonia?

Answer 10

interstitial pneumonia

Question 11

what are the C/S of BRSV?

Answer 11

• acute onset
• high fever
• severe dyspnea w/ open-mouthed breathing
• audible expiratory grunt

Question 12

bovine herpesvirus 1 is also called what?

Answer 12

infectious bovine rhinotracheitis, red nose

Question 13

BHV1 likes what type of cells? what does this mean?

Answer 13

epitheliotropism

means massive destruction of URT and tracheal epithelium (ulceration and necrosis)

Question 14

what are the C/S of BHV1? what is the pathognomonic lesion?

Answer 14

• 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

Question 15

how is BHV1 transmitted?

Answer 15

nasal + genital secretions

Question 16

true or false: bovine coronavirus is ubiquitous in cattle pops

Answer 16

true

Question 17

what is important to know about herpesviruses?

Answer 17

latency!
recrudescence of viral shedding occurs w/ immunosuppression

Question 18

what does bovine coronavirus cause in cattle?

Answer 18

broadly: pneumonia and diarrhea in calves and adults (among other things)

Question 19

what is the role of bacterial pathogens in BRD?

Answer 19

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

Question 20

what types of things suppress the bovine immune system in order for bac t to cause infection in BRD?

Answer 20

• stress
• viral infection
• parasitic infection
• ammonia fumes

Question 21

list the major bacteria involved in BRD

Answer 21

• Mannheimia haemolytica
• Pasteurella multocida
• Histophilus somni
• Mycoplasma bovis

(Biberstinia trehalosi – virulent, fast-acting relative of M. haemolytica)

Question 22

what gram are the BRD bacteria?

Answer 22

gram -, except for mycoplasma, which is gram +

Question 23

What ABs can you use to treat BRD and why would you choose/not choose them?

Answer 23

• 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)

Question 24

how does Mannheimia haemolytica cause disease?

Answer 24

commensal, ability to reside in URT among other non-pathogenic strains (A2), and then converts/overgrows under stressful stimuli to a pathogenic serotype (A1)

Question 25

which is frequently isolated as the cause of “shipping fever pneumonia”?

Answer 25

Mannheimia haemolytica

Question 26

what is the gross pathology for Mannheimeia haemolytica infection?

Answer 26

bilateral fibrinous bronchopneumonia w/ 25-75% lungs involved (cranioventral consolidation)

Question 27

Pasteurella multocida causes resp dz in what signalment?

Answer 27

younger cattle, esp dairy calves

Question 28

true or false: Pasteurella multocida requires additional predisposing factors to get pneumonia (like adverse climate, nutrition conditions, transportation, co-infections)

Answer 28

true

Question 29

what is the pathology of Pasteurella multocida?

Answer 29

suppurative bronchopneumonia

Question 30

what is the pathology of Histophilus somni pneumonia?

Answer 30

fibrinopurulent broncopneumonia (among other things –> it’s a systemic dz)

some strains will only cause severe fibrinous pleuritis w/o involvement of underlying lung

Question 31

if cattle are showing resp signs, CNS dz, sudden death bc of HF, and lameness, what should you be sus of?

Answer 31

Histophilus somni

Question 32

vasculitis is a predominant feature of what bacteria?

Answer 32

Histophilus somni

Question 33

Mycoplasma bovis has ____ dissemination, which results in what?

Answer 33

hematologic

pneumonia, otitis media, arthritis in calves

Question 34

true or false: Mycoplasma bovis may persist for life in infected animals

Answer 34

true

recrudescence of dz during periods of stress, continual transmission in herds

Question 35

what is the main cause of the damage during BRD?

Answer 35

the inflammatory reaction, not the pathogens themselves!

Neutrophils in lung don’t have anywhere to go, so they blow up (anti-apoptosis), which causes a cytokine storm –> huge inflammatory rxn

Question 36

tell me the C/S of BRD (they’re broad lol)

Answer 36

• naso-ocular discharge, depression, anorexia, fever as high as 42C, increased resp rate, moist cough
• worsening of symptoms: resp distress, encrusted muzzle, excessive tear prod., dyspnea, auscultation = pleural friction and muffled lung sounds if consolidated, distressed stance w/ elbow abducted and neck extended

Question 37

how do you dx BRD in live animals?

Answer 37

• C/S
• deep nasopharyngeal swab
• transtracheal wash
• bronchoalveolar lavage
• (paired sera)

Question 38

what C/S do you look for to dx BRD?

Answer 38

DART = depression, appetite, resp signs, temp

auscultation of lung field + trachea = primary dx modality

Question 39

a “sucking soup” noise in thorax is what?

Answer 39

often referred from distal trachea, indicative of lung consolidation

Question 40

list the 3 main dx tests in live animals from:
1. least invasive –> most invasive
2. from best –> worst diagnostic interpretation

Answer 40

1. deep nasopharyngeal swab, trans tracheal wash, bronchoalveolar lavage
2. bronchoalveolar lavage, trans tracheal wash, deep nasopharyngeal swab

Question 41

how do you dx BRD in dead animals?

Answer 41

• PM
• histo: 1cm thick tissues, lung (4 sections, cranial/caudal, both sides) + non lung
• bac t
• molecular

Question 42

what are the 3 kinds of vaccines for BRD?

Answer 42

• modified live: complete + long-lasting immunity, fewer doses required
• killed: at least 2 doses required
• intranasal: young animals when circulating maternal ABs have inhibitory effect on parenteral vax-induced immune response

Question 43

should you use NSAIDs in the tx of BRD?

Answer 43

I guess you can but there’s not enough evidence to say for certain if it actually helps