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Large Animal Medicine > Food Animal Respiratory Disease, Pt. 2 > Flashcards

Food Animal Respiratory Disease, Pt. 2 Flashcards

1
Q

What can all viral infections predispose cattle to?

A

Bovine Respiratory Disease Complex (BRDC)

  • shipping fever - feedlot calves
  • enzootic pneumonia - diary and veal calves
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2
Q

What are the 4 most common viruses and bacteria associated with BRDC?

A

VIRUSES - BVD, IBR, BRSV, PI3

BACTERIAL - Mannheimia hemolytica, Pasteurella multocida, Mycoplasma, Histophilus somni

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3
Q

What predisposes to BRDC?

A

STRESS and viral disease

  • shipping
  • comingling at sale barns
  • heat
  • poor nutrition
  • weaning
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4
Q

What treatment is recommended for BRDC? How is it controlled? What is prognosis like?

A

antibitoics and Flunixin meglumine

vaccines, control stress and viral infections

good

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5
Q

What causes infectious bovine rhinotracheitis? How is it transmitted?

A

bovine herpesvirus-1

  • oronasal secretions of infected
  • reactivation from trigeminal ganglia in clinically recovered cattle with immunocompromization
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6
Q

What are some hosts of infectious bovine rhinotracheitis?

A
  • cattle
  • buffalos
  • small ruminants
  • wild ruminants
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7
Q

What is the characteristic sign of infectious bovine rhinotracheitis? What else is seen?

A

red nose - rhinitis causes hyperemia and ulceration of the mucosa

  • bilateral conjunctivitis +/- corneal opacity without ulcers
  • fever >104 F
  • abortion - BHV-1.2
  • pustular vulvovaginitis - BHV-1.2
  • encephalitis - BHV-1.3 or BHV-5
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8
Q

What are the 2 forms of transmission of infectious bovine rhinotracheitis? What are 2 risk factors?

A
  1. RESPIRATORY - droplets, nasal secretions
  2. GENITAL - semen, genital fluid, fetal fluid, venereal
  • ALL ages and breeds are susceptible, but most common in those above 6 months of age
  • unvaccinated herds - breeding cattle are highly susceptible to epidemics of respiratory disease and abortion
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9
Q

What are the 5 clinical forms of infectious bovine rhinotracheitis?

A
  1. respiratory - rhinitis (red nose)
  2. ocular
  3. abortive (IPV)
  4. systemic disease - newborn calves
  5. encephalitic
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10
Q

What necropsy lesions are associated with infectious bovine rhinotracheitis? What are 2 methods of diagnosis?

A

reddened, congested tracheal mucosa with secondary bacterial infections

  1. virus isolation from nasal or ocular swabs
  2. serology - paired samples ONLY with a 4 fold rise in the 2nd sample taken 2-3 weeks later
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11
Q

What cattle are most commonly affected by bovine respiratory syncytial virus? How is it spread?

A

feeder age dairy and beef calves and naive adults –> fatalities associated

oronasal secretions

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12
Q

What is the pathophysiology of bovine respiratory syncytial virus? What does it have a predilection for?

A

CYTOPATHIC

  • forms syncytial cells in infected tissues, causing the formation of multinuclear cell fusion
  • induced cytokine production by cellular immunity

lower respiratory tract

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13
Q

What are some signs of bovine respiratory syncytial virus? What are 2 unique signs?

A
  • depressed, off feed
  • cough, severe dyspnea
  • high fever >104

lung and SQ emphysema

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14
Q

What are 3 signs of bovine respiratory syncytial virus on necropsy?

A
  1. lungs fail to collapse when thorax is opened
  2. pulmonary edema and interstitial pneumonia
  3. emphysema
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15
Q

How is bovine respiratory syncytial virus diagnosed? Treated?

A
  • clinical signs and necropsy lesions
  • virus isolation - difficult
  • serology

NSAIDs +/- corticosteroids

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16
Q

What causes bovine viral diarrhea? What are the 3 ways it is classified?

A

Flaviviridae, Pestivirus (RNA)

  1. BIOTYPE - way it behaves in culture (cytopathic vs. non-cytopathic –> both capable of causing disease!)
  2. GENOTYPE - Type 1a, 1b, 2a (2 is newer and associated with severe hemorrhagic syndrome)
  3. STRAIN - small genetic differences
17
Q

What serves as the main reservoir for BVD? What are the 3 courses of disease?

A

persistently infected –> spread through infected body fluids

  1. acute infection - usually subclinical
  2. in-utero fetal infection
  3. persistent infection - mucosal disease
18
Q

What clinical signs are associated with acute infection of BVD?

A
  • anorexia, depression
  • high fever
  • oculonasal d/c
  • salivation
  • mucosal erosion
  • diarrhea
  • leukopenia, thrombocytopenia (Type II, older cattle)
  • may have NO signs –> immunosuppression

(all post-natal infections are acute, most are subclinical)

19
Q

How does fetal infection of BVD occur? What does outcome depend on?

A

dam is infected or viremic and virus infects fetus transplacentally –> fetal infection continues independent of maternal infection

stage of fetal development
- <150 days = death and abortion
- 100-150 days = congenital malformation
- 40-125 days = persistently infected calf
- >150 days = normal calf with acquired immunity to BVD, may be born weak

20
Q

When does mucosal disease occur with BVD? How does this typically develop?

A

fetal infection with noncytopathic persistant virus only - calf’s body doesn’t recognize the virus as foreign (any calf born to a PI cow WILL BE PI)

calf may look normal at birth and secretes large amounts of virus throughout its life +/- chronic poor-doers

21
Q

What are the 4 possible outcomes of a PI animal infected with BVD?

A
22
Q

What are 3 necropsy lesions seen with BVD?

A
  1. mucosal erosions seen in oral cavity, nose, esophagus, rumen, omasum, and abomasum
  2. necrosis of Peyer’s patches in the ileum
  3. erosions on coronary band and interdigital skin
23
Q

What is the gold standard for diagnosing BVD? What are 2 other options?

A

viral isolation - blood antemortem, best for detecting acute infection

  1. serology - paired samples
  2. PI screening tests - Microplate VI, antigen-capture ELISA, PCR, IHC on skin samples (skin notch) - poor detection of acute infections
24
Q

What treatment is recommended for mucosal disease with BVD? How is infection controlled?

A

euthanasia

  • vaccination - does not completely protect fetus
  • detection and removal of PI carriers
  • biosecurity - isolation of new cattle for 3 weeks prior to comingling and testing prior to addition
25
Q

What is the standard vaccine issues for BRDC?

A

4 way - BRV, BVD, PI3, BRSV

  • often in combo with Leptospirosis
  • injectable and nasal options
  • modified live > killed - produced better cell-mediated immunity, killed required 2 doses spaced 2-3 weeks apart, killed is more $$$
26
Q

What is the most economically significant disease of beef cattle?

A

BRDC - death, chronic infection, treatment cost, production loss

27
Q

What cattle are most commonly affected by enzootic pneumonia? What is the most common cause of outbreaks?

A

housed dairy and veal calves 2-6 months old

Pasteurella multocida

28
Q

What are the 3 steps of progression of shipping fever?

A
  1. stress impairs the immune system - commingling, poor weather, weaning, transport, overcrowding, poor nutrition, vaccination, castration
  2. primary viral respiratory infection
  3. further impairment of respiratory immunity due to destruction of cilia and alveolar macrophages
29
Q

What are the 4 most common bacteria associated with shipping fever?

A
  1. Mannheimis hemolytica - most common, inhabitant of nasopharynx, virulence enhanced by bacterial leukotoxin
  2. Pasteurella multocida - common in outbreaks in dairy calves (enzootic pneumonia)
  3. Histophilus somni - sporadic in US
  4. Mycoplasma bovis
30
Q

When are clinical signs of shipping fever seen? What signs are associated?

A

first 3 weeks after stress

  • depression - drooped ears and head, weakness, will not move when approached
  • anorexia - decreased rumen fill, sunken paralumbar fossa (dehydrated)
  • nasal d/c, cough
  • increased rectal temperature, RR (open mouth breathing common), respiratory sounds (wheezes, pleural friction rubs) cranioventrally
31
Q

What is the characteristic necropsy lesion of shipping fever? What else is seen?

A

consolidation and dark discoloration of cranioventral lung lobes

  • fibrinous pleuritis
  • pulmonary abscesses with chronic cases
32
Q

What are 3 options for treating shipping fever? What is not used?

A
  1. antibiotics - all labeled for bacterial pneumonia
  2. anti-inflammatories - Banamine (Flunixin meglumine)
  3. vitamin C, B

fluids

33
Q

What are some good options for antibiotics for treating shipping fever? What is not commonly used?

A
  • Ceftiofur - 3-4 day slaughter withdrawal
  • OTC - 28 day withdrawal
  • Tilmicosin (Micotil)
  • Florfenicol
  • Draxxin - also covers Mycoplasma

Baytril/Danofloxacin (A180) - not for use in cattle intended for dairy production or in calves to be processed for veal

34
Q

What is metaphylaxis? What use does it have for shipping fever?

A

mass treatment of all animals in the hopes of preventing outbreaks

significantly decreases morbidity and case fatality + improve performance

  • most beneficial when >40% of animals are anticipated to become ill
35
Q

What ancillary treatment is done for BRDC?

A
  • oral fluids
  • isolate, space, shelter
  • provide dry and warm environment
  • plenty of palatable feed and water
  • tripelennamine hydrochloride (Re-Covr)
36
Q

How can stress be minimized to prevent BRDC? What biosecurity is recommended?

A
  • work calves well in advance of weaning
  • wean calves 4-6 weeks before marketing

quarantine 2-3 weeks and clean between

37
Q

How are modified live vaccines handled? When are they not given?

A
  • MLV loses viability a few hours after reconstitution
  • disinfectant and soap residues left in equipment will kill MLV

pregnant cows - modified live IBR can cause temporary infertility due to follicular necrosis + minute chance for MLV to be contaminated with virulent viruses or to cause mucosal disease in PI animals

38
Q

How does the nasal IBR and PI3 vaccines work?

A

virus cannot survive at normal body temperatures, but replicates in the upper airways, resulting in interferon production and increased secretory IgA at point of entry

  • safe in pregnant cows and contact animals
39
Q

What are bacterin vaccines for BRDC? What affect do they have?

A

M. hemolytica, P. multocida vaccines with a maximum response within 2-3 weeks following vaccination but wanes by 6 weeks

decreases morbidity

Large Animal Medicine (34 decks)

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