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Vet clinics of N. America-Food Animals > 2022.Iss3.liverabnormalitiesinCattle > Flashcards

2022.Iss3.liverabnormalitiesinCattle Flashcards

1
Q

Roughage and Dietary influence on Liver abscesses

which antibiotic has been shown to be effective in reducing liver abscess prevalence?

A

tylosin

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2
Q

Roughage and Dietary influence on Liver abscesses

Which diets are shown to reduce incidence of liver abscessation?

A

roughage
**grain diets and ruminal acidosis are predisposing factor to liver abscesses

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3
Q

Roughage and Dietary influence on Liver abscesses

Which bacteria are implicated in liver abscess formation?

A

Fusobacterium necrophorum

Trueperella pyogenes

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4
Q

Antimicrobial and biological methods to control liver abscesses

Are there commercial vaccines available for control of liver abscesses?

A

No

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5
Q

Antimicrobial and biological methods to control liver abscesses

What is bacitracin, MOA?

A

produced by Bacillus licheniformis and B subtilis

MOA: inhibits peptidoglycan synthesis in bacteria by block phosphorylase reactions nonspecifically

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6
Q

Antimicrobial and biological methods to control liver abscesses

How effective is bacitracin in control of liver abscesses?

A

-no association with liver abscess prevalence
**liver abscess great in the study (72% condemned)

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7
Q

Antimicrobial and biological methods to control liver abscesses

What is the efficacy of chlortetracycline in reducing liver abscess formation?

A

reduces liver abscess formation by about 20-35% in cattle

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8
Q

Antimicrobial and biological methods to control liver abscesses

What is the efficacy of neomycin sulfate & oxytetracycline in reducing liver abscess formation?

A

no evidence evaluating the efficacy of neomycin sulfate & oxytet

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9
Q

Antimicrobial and biological methods to control liver abscesses

What is the MOA of tetracyclines?

A

bind 30S ribosomal unit of susceptible organisms

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10
Q

Antimicrobial and biological methods to control liver abscesses

What is the MOA of tylosin?

A

macrolide: inhibit protein synthesis by binding to 50S ribosomal subunit of organisms

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11
Q

Antimicrobial and biological methods to control liver abscesses

which antimicrobial has the most data supporting its efficacy out of all the antimicrobials used in controlling liver abscesses?

A

Tylosin

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12
Q

Antimicrobial and biological methods to control liver abscesses

Virginiamycin mode of action

A

bactericidal
inhibits 23S ribosomal subunit

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13
Q

Antimicrobial and biological methods to control liver abscesses

What are the six different antimicrobials approved by the FDA for use in the USA?

A
  1. Tylosin
  2. Virginiamycin
  3. oxytetracycline
  4. neomycin sulfate
  5. chlortetracycline
  6. Bacitracin methylene disalicylate
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14
Q

Pathogenesis of Liver Abscesses in Cattle

What are widely accepted predisposing factors for the occurrence of liver abscesses?

A

ruminal acidosis
rumenitis

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15
Q

Pathogenesis of Liver Abscesses in Cattle

What are the virulence factors of Fusobacterium necrophorum that contribute to its pathogenesis?

A

primarily leukotoxin & endotoxic LPS

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16
Q

Pathogenesis of Liver Abscesses in Cattle

What are routes of entry of bacteria into the liver?

A
  1. hepatic artery
  2. umbilical vein (neonatal calves)
  3. direct extension from adjacent organs (often the reticulum)
  4. bile duct
  5. peritoneal cavity
  6. portal vein
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17
Q

Pathogenesis of Liver Abscesses in Cattle

Ruminal gut barrier function is disrupted by:

A

-acidity (mostly VFAs)
-hyperosmolarity b/c of inc solute concentrations (sugars & acids)
-toxins (endotoxin, histamine, etc)
-immune mediators (cytokines)

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18
Q

Pathogenesis of Liver Abscesses in Cattle

What are diets that predispose to ruminal acidosis & subsequent rumenitis:

A
  1. inadequate roughage in diet
  2. diets containing rapidly fermentable grains, such as wheat and barley or processed grains, such as steam-flaked or high-moisture corn
  3. Long feeding duration such as that observed with dairy calves raised for beef production
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19
Q

Pathogenesis of Liver Abscesses in Cattle

Which bacteria is synergistic with F necrophorum, allowing it to proliferate in its necessary anaerobic environment?

A

Truepurella pyogenes– facultative anaerobic

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20
Q

Liver Disorders Associated with Metabolic Imbalances in Dairy Cows

fatty liver & negative energy balance is associated with a greater incidence of what periparturient disorders?

A

dystocia
infections
inflammation

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21
Q

Liver Disorders Associated with Metabolic Imbalances in Dairy Cows

A normal liver should contain what percentage of triglycerides?

A

<1%

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22
Q

Liver Disorders Associated with Metabolic Imbalances in Dairy Cows

What percentage of triglyerides are present in a severely fatty liver?

A

> 10%
moderate: 5-10%

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23
Q

Toxicologic insults to the Bovine Liver

Which region of the liver (on the cellular level) is the common affected by necrosis in toxic insults?

A

centribolubar– d/t high concentration of cytohcrom P450 enzymes in this region

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24
Q

Toxicologic insults to the Bovine Liver

Copper toxicity in cattle is most commonly caused by:

A

-over supplementation
-chronci consumption of feeds or feedstuffs high in copper

25
Toxicologic insults to the Bovine Liver What are copper antagonists?
sulfure molybdenum
26
Toxicologic insults to the Bovine Liver Describe the pathogenesis of copper toxicity.
-copper stored in lysosomes w/in hepatocytes until stressful event causes release -systemic copper overwhelms the binding capacity of ceruloplasmin --> oxidative damge to RBCs &from exposure to unbound copper --> hemorrhagic crisis & death
27
Toxicologic insults to the Bovine Liver How is copper toxicity definitively diagnosed?
copper levels in the liver
28
Toxicologic insults to the Bovine Liver What is the most common fungal spp implicated in alfatoxicosis?
Aspergillus flavus
29
Toxicologic insults to the Bovine Liver IN alfatoxicosis, what are environmental conditions that favor fungal growth?
-high relative humidity (>75%) -temperatures ranging 12-42C -damage to seeds during harvesting or rpocessing
30
Toxicologic insults to the Bovine Liver What are the major types of alfatoxins produced?
B1 or B2 G1 or G2 B1** most common type produces & most toxic & most carcinogenic
31
Toxicologic insults to the Bovine Liver What hydroxylated alfatoxins are metabolites seen in milk & meat products from exposed animals?
M1 or M2
32
Toxicologic insults to the Bovine Liver Which grains are most commonly associated with alfatoxicosis in cattle?
cereal grains cotton seed peanuts or peanut byproducts
33
Toxicologic insults to the Bovine Liver fumonisin mycotoxin, is commonly associated with what grains?
corn or corn based feeds
34
Toxicologic insults to the Bovine Liver What does fumonisin cause in horses & pigs?
equine leukoencephalomalacia porcine pulmonary edema
35
Toxicologic insults to the Bovine Liver Pyrrolizidine alkaloid toxicity pathogenesis
bioactivation of PA in the liver by cytochrome P450 system yields toxic emtabolites that damage cellular proteins and nucleis acids
36
Toxicologic insults to the Bovine Liver With Pyrrolizidine alkaloid toxicity, what lesions are characteristic in the liver?
megalocytosis & periportal necrosis
37
Toxicologic insults to the Bovine Liver Secondary photosensitization, seen in cattle is commonly due to
hepatic dysfunction, results in decreased capacity of the liver to metabolize phylloerythrin (breakdown product of chlorophyll)
38
Toxicologic insults to the Bovine Liver What are the two most commonly indicated nutrients triggering toxic cyanobacteria/blue-green algae blooms?
nitrogen phosphorus
39
Toxicologic insults to the Bovine Liver Clinical cases of blue-green algae toxicity (cyanobacteria), are caused by what toxins?
microcystins-- hepatotoxic anatoxins-- neurotixc
40
Toxicologic insults to the Bovine Liver Describe the pathogenesis of blue-green algae toxicosis.
cyanobacteria exposed to gastric environment-- release of microcystins-- absorption to portal blood stream & distributed to liver Liver: oxidative damage, mitochondrial changes & cell apoptosis --->death d/t intrahepatic hemorrhage--failure of sinusoidal endothelium
41
Effect of Liver Abscessation on Carcass Outcomes Liver abscess prevalence exceeds what percentage of a pen of finished cattle?
20%
42
Effect of Liver Abscessation on Carcass Outcomes What is the significance of liver abscessation?
-financial loss from condemnation ($8-$189 per animal) -dec hot carcass weights
43
Toxicology and Analytical Chemistry Collecting gastrointestinal contents post mortem is diagnostic for what toxins?
ammonia blue-green algae toxins botulism cantharidin gossypol heavy metals ionophores plant/seed identification pH plant toxins pesticides rodentixicdes
44
Toxicology and Analytical Chemistry Collecting the kidney on post mortem is diagnostic for what toxins?
drugs/medications heavy metals
45
Toxicology and Analytical Chemistry Collecting liver on post mortem is diagnostic for what toxins?
drugs/medications heavy metals pesticides plant toxins rodenticides sulfur trace nutrients vitamin A & E
46
Toxicology and Analytical Chemistry Collecting milk on post mortem is diagnostic for what toxins?
alfatoxin antibiotics pesticides heavy metals (lead)
47
Toxicology and Analytical Chemistry Collecting ocular fluid on post mortem is diagnostic for what toxins?
ammonia magnesium sodium
48
Toxicology and Analytical Chemistry Collecting urine on post mortem is diagnostic for what toxins?
anatoxin-a cantharidin drugs/medications plant toxins
49
Toxicology and Analytical Chemistry Collecting antemortem samples, of liver is diagnostic for what potential toxins?
heavy metals trace nutrients
50
Toxicology and Analytical Chemistry Collecting antemortem samples, blood is diagnostic for what potential toxins?
acetylcholinesterase activity & cyanide drugs/medications heavy metals trace nutrients pesticides rodenticides
51
Toxicology and Analytical Chemistry Collecting antemortem samples, of feces is diagnostic for what potential toxins?
botulism
52
Toxicology and Analytical Chemistry Collecting antemortem samples, of serum/plasma is diagnostic for what potential toxins?
ammonia antitoxin-a botulism canthariidn drugs/meds ionophores nitrate pesticides rodenticides trace nutrients vit A & E
53
Toxicology and Analytical Chemistry Collecting antemortem samples, of hair is diagnostic for what potential toxins?
growth promotants
54
Toxicology and Analytical Chemistry Collecting antemortem samples, of milk is diagnostic for what potential toxins?
aflatoxin antibiotics pesticides heavy metals (lead)
55
Toxicology and Analytical Chemistry Collecting antemortem samples, of urine is diagnostic for what potential toxins?
ammonia anatoxin-a cantharidin drugs/medications plant toxins
56
The role of histopathology in ruminant diagnostics What are common causes of pulmonary edema in ruminants?
cardiac insufficiency BRD sepsis
57
The role of histopathology in ruminant diagnostics Describe microscopic lesions seen in atypical interstitial pneumonia
pulmonary edema & congestion emphysema fibrosis type II pneumocyte hyperplasia hyaline membranes lining alovelar wall
58
The role of histopathology in ruminant diagnostics If myocardial inflammation, degeneration and/or necrosis in ruminants shoul lead to suspecion of what toxins?
ionophores gossypol plants of genus Senna (coffee senna) Japanese Yew *taxus cuspidate)

Vet clinics of N. America-Food Animals (11 decks)

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