Lecture 6 10/15/24

Question 1

What are the characteristics of bovine respiratory syncytial virus?

Answer 1

-causes formation of syncytial cells in the lungs
-very common
-most cattle are likely seropositive

Question 2

What are the two manifestations of BRSV?

Answer 2

-upper respiratory, which is more common
-lower respiratory

Question 3

What are the clinical signs of an upper BRSV infection?

Answer 3

-high fever
-ptyalism
-cough
-increased lung sounds
-anorexia
-oculonasal discharge

Question 4

What are the characteristics of lower BRSV infection?

Answer 4

-causes interstitial pneumonia that alters the architecture of the lungs
-inflammation occurs between alveoli
-ruptured alveoli result in emphysematous bullae and subcutaneous emphysema

Question 5

What are the clinical signs seen in calves with interstitial pneumonia due to BRSV?

Answer 5

-expiratory dyspnea
-open-mouthed breathing
-respiratory collapse

Question 6

What is the signalment of cattle with BRSV?

Answer 6

cattle can be in any age group

Question 7

Why is BRSV difficult to culture?

Answer 7

the virus is very fragile and not likely to grow/survive

Question 8

Which diagnostic methods are used for BRSV?

Answer 8

-immunohistochemistry
-FA
-PCR
-necropsy (easiest diagnostic method)

Question 9

How is BRSV treated?

Answer 9

-corticosteroids
-NSAIDs
-antihistamines

Question 10

How is BRSV prevented?

Answer 10

vaccination (MLV available)

Question 11

What are the clinical signs of para-influenza 3 virus?

Answer 11

-often subclinical
-fever
-cough
-nasal and ocular discharge

Question 12

What is the pathophysiology of para-influenza 3 virus?

Answer 12

weakens immune system to allow for synergistic infections

Question 13

How is para-influenza 3 virus diagnosed?

Answer 13

-PCR
-virus isolation
-serology

Question 14

How is para-influenza 3 virus prevented?

Answer 14

vaccination

Question 15

What are the clinical signs of bovine coronavirus?

Answer 15

-fever
-nasal and ocular discharge
-coughing
-diarrhea

Question 16

What are important characteristics of bovine coronavirus?

Answer 16

-same virus that causes neonatal diarrhea and winter dysentery also causes resp. disease
-clinical signs of viral infection can worsen following secondary bacterial pneumonia

Question 17

How is bovine coronavirus prevented from causing resp disease?

Answer 17

by using the bovine rota-coronavirus vx off label as an intranasal vx

Question 18

What is the importance of Mannheima haemolytica serotypes?

Answer 18

-all serotypes can be commensals of the nasal cavity
-serotypes A1 and A6 are commonly pathogenic under correct conditions

Question 19

What are the characteristics of M. haemolytica leukotoxin?

Answer 19

-main virulence factor
-binds to beta-2 integrins on ruminant leukocyte and punches hole in cell
-increases number of beta-2 receptors and induces apoptosis
-induces cell lysis

Question 20

Why is the lysis of neutrophils in M. haemolytica infection important?

Answer 20

toxic compounds in the neutrophils spill out and damage the tissue

Question 21

What are the characteristics of M. haemolytica endotoxin?

Answer 21

-induces cytokine storm
-production of IL-8 increases neutrophil migration into lungs

Question 22

Which pathogen is the most economically significant in cattle?

Answer 22

M. haemolytica

Question 23

What must be contained in a good vaccine against M. haemolytica?

Answer 23

purified leukotoxoid

Question 24

What is important to note about the M. haemolytica toxoid vx?

Answer 24

immunity is short lived

Question 25

What are the characteristics of Pasteurella multocida?

Answer 25

-not as severe as M. haemolytica -cattle inhale small amounts of bacteria from the nasopharynx -small area is colonized by the bacteria; slowly expands to form larger lesion

Question 26

What is the pathophysiology of P. multocida?

Answer 26

-chronic resp damage is necessary for bacteria to colonize lung -seen in dairy calves housed in poorly ventilated barns -takes over after an infection with M. haemolytica in feedlot cattle

Question 27

What type of pneumonia is caused by M. haemolytica?

Answer 27

fibrinous pleuropneumonia

Question 28

What type of pneumonia is caused by P. multocida?

Answer 28

bronchopneumonia that is less severe than that associated with M. haemolytica

Question 29

What are the downsides to vaccinating against bacterial pathogens?

Answer 29

-not efficacious -not long lasting -disrupting effects of stress and viral infections is more beneficial

Question 30

What is the pathophysiology of Histophilus somni?

Answer 30

-forms lesions on endothelial membranes -causes vasculitis and thrombosis -affects multiple organ systems -induces endothelial cell death and exposes the basement membrane, activating the coag. cascade

Question 31

What are the four "flavors" of Mycoplasma bovis?

Answer 31

-pneumonia -mastitis -otitis -septic arthritis

Question 32

What is important about M. bovis infection?

Answer 32

-causes multisystemic manifestations -most infections likely start as a pneumonia and the bacteria spread elsewhere in the body

Question 33

Why are M. bovis infections difficult to treat?

Answer 33

-chronic and non-responsive to antibiotics -no cell wall; beta-lactams are useless

Question 34

Why is M. bovis difficult to vaccinate against?

Answer 34

the surface proteins are variable

Question 35

Which diagnostic methods are primarily used to diagnose bacterial pathogens?

Answer 35

-culture -PCR

Question 36

Which samples can be used to diagnose bact. infections?

Answer 36

-nasal swab -deep nasopharyngeal swab -TTW -BAL -pleurocentesis -lung tissue biopsy

Question 37

Why is diagnosing bacterial pathogens difficult?

Answer 37

many of the bacterial pathogens that cause disease are also commensals of the nasal cavity

Question 38

What is the importance of ultrasound?

Answer 38

-best tool for evaluating pulmonary surface -can be used for early detection of pulmonary disease

Question 39

What are the two triggers for treating calves with pneumonia?

Answer 39

-clinical signs such as poor appetite, lack of rumen fill, depression, and increased resp. rate -increased temperature; greater than 104

Question 40

What are the problems with the current method for identifying calves requiring pneumonia treatment?

Answer 40

-sensitivity is 62% and specificity is 63% -greater than 50% of calves with evidence of pneumonia at slaughter were never treated

Question 41

How is treatment duration determined?

Answer 41

-attitude -appetite -weight gain -rectal temp

Question 42

How long are cattle given to respond before changing antibiotic/treatment?

Answer 42

3 days

Question 43

Which methods can be useful in the identification of pneumonia and treatment duration determinations?

Answer 43

-biomarkers such as haptoglobin and haptoglobin-MMP -activity monitors

Question 44

What is BRD metaphylaxis?

Answer 44

treating animals that are at high risk for BRD/are incubating BRD but do not yet have clinical signs

Question 45

Why is it important to culture an animal prior to treatment whenever possible?

Answer 45

-culturing before treatment allows for identification of the pathogen and its actual sensitivity profile -culturing after treatment can cause pathogen to be missed or sensitivity profile to show resistance

Question 46

What are the two perspectives on NSAID use in treating BRD?

Answer 46

one cow at a time: -want to control inflammation causing pneumonia -NSAIDs cause clinical improvement many cows at a time: -treatment costs outweigh benefits of NSAID use -no effect on weight gain or economic improvement