BRD Clinical Diagnosis Flashcards

1
Q

What is the prevalence of BRD in Pre-weaning (Cow-Calf)?

A
  • ~20% of herds impacted
  • Within herd prevalence 5-15%
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2
Q

What is the prevalence of BRD in Post-Weaning (Stocker/Feedyard)?

A
  • Almost all operations impacted
  • 16.2% feedyard cattle treated for BRD
  • Avg Cost / case = $23.60
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3
Q

What are the factors that contribute to the development of BRD?

A
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4
Q

What are the Viral Pathogens that cause BRD?

A
  • Bovine Herpesvirus-1 (BHV-1; IBR)
  • Bovine Viral Diarrhea (BVD)
  • Bovine Parainfluenza virus type 3 (PI-3)
  • Bovine respiratory syncytial virus (BRSV)
  • Gen characteristics:
    • infectious, contagious
    • influence host response to additional pathogens
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5
Q

What is BHV-1; IBR? Reservoir? Transmission? Clinical syndrome?

A
  • Reservoir - Cattle
    • new introductions / shedding latent virus
  • Transmission - highly contagious
    • oro-nasal secretions
    • aerosol
  • Clinical Syndrome:
    • Mild to severe
    • Tracheitis
    • +/- ocular involvement
    • Potential for reproductive impact in breeding stock
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6
Q

What is Bovine Viral Diarrhea virus (BVD)? Reservoir? Transmission?

A
  • Highly mutable RNA virus (pestivirus)
    • Multiple genotypes and phenotypes
  • Reservoir - Cattle
    • Transient infections
    • Persistent infection (PI)
  • Transmission - Highly contagious
    • oro-nasal secretions
    • vertical transmission
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7
Q

How are persistently infected BVD cattle made? What are they?

A
  • Calf (fetus) exposed through the dam at day 40-130 of gestation
  • May appear normal
  • Shed virus constantly
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8
Q

What is the Clinical syndrome of BVD?

A
  • Mild to severe
  • Immunosuppression
  • Syndromes related to age / cattle class:
    • Scours (young calves)
    • BRD
    • Reproductive
    • Mucosal Disease
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9
Q

What pathology is develops from exposure to BVD and/or Mannheimia hemolytica

A
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10
Q

What is Bovine Respiratory Syncytial Virus? Reservoir? Transmission? Clinical Syndrome?

A
  • Pneumovirus - multiple strains
  • Reservoir- Cattle
    • young cattle more susceptible
  • Transmission - contagious
    • oro-nasal secretions
    • aerosol transmission
  • Clinical Syndrome
    • Pyrexia
    • Acute Respiratory Distress
      • Bronchiole constriction
      • Emphysema
      • Wet, heavy lungs
    • Nasal Discharge
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11
Q

What are the bacterial pathogens that cause BRD? general characteristics?

A
  • Mannheimia haemolytica
  • Pasteurella multocida
  • Histophils somni
  • Mycoplasma bovis
  • Gen Characteristics:
    • Augment pulmonary damage
    • Reservoir - cattle
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12
Q

What is Mannheimia haemolytia? Reservoir? Transmission?

A
  • Agent:
    • Gram (-) bacteria
    • Formally known as Pasteurella haemolytica
    • Serotypes 1 & 2 +/- leukotoxin
  • Reservoir - Cattle
    • Commensal
    • Normal inhabitants of nasal pharyngeal mucosa (tonsillar crypts)
  • Transmission - Questionable contagious nature
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13
Q

What is the clinical syndrome of Mannheimia haemolytica?

A
  • Leukotoxin causes pulmonary damage and systemic signs
  • Acute and chronic illness
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14
Q

What is Pasteurella multocida? Reservoir? Transmission? clinical syndrome?

A
  • Gram negative bacteria
  • Reservoir: cattle (commensal)
  • Transmission: Questionable contagious nature
  • Clinical syndrome:
    • May cause fibrinous pneumonia in chronic cases
    • Acute and chronic illness
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15
Q

What is Mycoplasma bovis? Reservoir? Transmission? Clinical syndrom?

A
  • Agent:
    • Mollicutes class
    • >102 species of mycoplasma
  • Reservoir: Cattle (nasal passages)
  • Tranmission:
    • Oro-nasal
    • Aerosol
  • Clinical Syndrome:
    • Opportunistic organism
    • Slow growth ⇢ chronic disease (abscesses)
    • Multiple presentations:
      • Respiratory
      • Arthritis / tenosynovitis
      • Ear infections
      • Mastitis
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16
Q

What is the epidemiology of Acute Interstitial Pneumonia (AIP)

A
  • 72% feedlots have AIP
    • affects 2.8% cattle
  • Sporadic occurrence
  • More common in heifers
  • Later in feeding period (>60d)
    • avg days at death 114-136
  • Higher rates in summer
  • High case fatality (near 100%)
17
Q

What is the Etiology of Acute Interstitial Pneumonia (AIP)

A
  • Questionable association with common microbial pathogens
  • Unknown: dust, allergies, toxicity
  • Pneumotoxic effects of 3 methlindole
  • Multiple factors
18
Q

What are the clinical signs of AIP

A
  • Rapid disease onset - often fatal
  • Respiratory signs, but no fever
  • Open mouth breathing
  • May be found dead in pen
  • Nasal, oral discharge
19
Q

What is the pathology of AIP

A
  • Bronchiole constriction - lungs fail to collapse
  • Marked interlobular emphysema
  • Marked interlobular edema
  • Heavy, wet lungs
20
Q

How long does it take calves to get sick post infectious agent challenge

A
21
Q

What biophysical profile changes occur early in BRD?

A
  • Minimal changes in respiratory/heart rates
  • Complete blood count (CBC)/Chemistry panel
    • few meaningful changes
    • Inflammatory profile
22
Q

What are the common clinical signs of BRD? additional signs?

A
  • DART:
    • Depression
    • Anorexia
    • Respiration Increased
    • Temperature
  • Coughing
  • nasal discharge
  • Isolation from group
23
Q

What is the accuracy of Visual observation at diagnosing BRD?

A
  • Low
  • Sensitivity - 27-63%
  • Specificity - 63-92%
24
Q

When should be recommend ranchers observe their cattle?

A
  • At feed time (convenience) AND
  • At times of decreased social pressure (i.e. everyone else is eating so I should eat, everyone is moving to the other side of the pen so I need to move)
25
Q

What is the respiratory score chart based on?

A
  • 4 level scale
  • Rectal temperature
  • Presence of cough
  • Nasal discharge
  • Eye score
  • Ear score
26
Q

what is the cost of an imperfect diagnosis?

A
  • False negatives
    • Subclinical disease cost $39/head
  • False positives
    • Unnecessary treatments
27
Q

What are the available ancillary pathogen diagnostics?

A
28
Q

How can misdiagnosis be decreased through additional testing?

A

Improving Specificity

  • Use when false positives are a problem (low specificity of diagnostic test, low prevalence of disease, or high cost of false positive
  • Consider testing in series (or rather the calf should be positive on several tests to consider positive
    • E.g. Clinical diagnosis followed by confirmatory test

Improving Sensitivity

  • Use when false negatives are a problem (low sensitivity or diagnostic test, high prevalence of disease, or high cost of false negatives)
  • Consider testing in parallel (or rather apply multiple tests and consider calf positive if any of the results are positive)
    • E.g. apply clinical diagnosis daily and monitor individual calf feed intake
29
Q

What is the sensitivity and specificity of thoracic auscultation and ultrasonography?

A