Lab 6 MCQ | Quizlet

A 2-week-old calf and an adult cow ingest identical amounts of nitrite. The calf is more likely to develop severe poisoning primarily because of

a. Increased nitrate reduction by ruminal microorganisms

b. Increased conversion of nitrite to ammonia

c. Reduced methemoglobin reductase activity

d. Increased renal nitrate elimination

c. Reduced methemoglobin reductase activity

Which environmental condition is MOST likely to increase nitrate accumulation in plants?

a. Warm sunny weather with adequate irrigation

b. Drought followed by cloudy weather

c. Mature plant growth

d. High phosphorus fertilization

b. Drought followed by cloudy weather

Which plant characteristic is associated with increased nitrate concentration?

a. Advanced maturity

b. High fiber content

c. Young age

d. Seed production

c. Young age

Nitrite poisoning is generally more common than nitrate poisoning because

a. Nitrite is less readily absorbed

b. Nitrate is primarily an irritant

c. Nitrite is rapidly converted to ammonia in all species

d. Nitrite cannot form methemoglobin

b. Nitrate is primarily an irritant

Which species would be expected to have the HIGHEST susceptibility to nitrite poisoning?

a. Cattle

b. Sheep

c. Horse

d. Dog

d. Dog

A major reason monogastric animals are susceptible to nitrite intoxication is

a. Increased ruminal conversion of nitrate to nitrite

b. Inability to convert nitrite efficiently to ammonia

c. Increased dietary nitrate intake

d. Increased production of methemoglobin reductase

b. Inability to convert nitrite efficiently to ammonia

Which factor decreases the risk of nitrate poisoning in ruminants?

a. Hunger

b. Sudden exposure to high-nitrate feed

c. Adaptation through gradual exposure

d. Frost-damaged pasture

c. Adaptation through gradual exposure

Frequent ingestion of small amounts of nitrate-rich forage may reduce poisoning risk because

a. It increases renal clearance

b. It induces hepatic metabolism

c. Rumen microorganisms adapt

d. It decreases feed intake

c. Rumen microorganisms adapt

Which statement regarding newborn animals is CORRECT?

a. Newborn hemoglobin is less susceptible to oxidation

b. Methemoglobin reductase activity is increased

c. Pentose phosphate pathway activity is reduced

d. Nitrate absorption is reduced

c. Pentose phosphate pathway activity is reduced

Nitrate poisoning is particularly associated with ruminants because

a. They absorb nitrate more rapidly than monogastrics

b. Their microorganisms convert nitrate to nitrite

c. They possess lower blood volume

d. They lack methemoglobin reductase

b. Their microorganisms convert nitrate to nitrite

Nitrite is absorbed most rapidly after exposure, with detectable systemic absorption occurring within approximately

a. 8 minutes

b. 30 minutes

c. 2 hours

d. 12 hours

a. 8 minutes

Compared with nitrite, nitrate is characterized by

a. Longer biological half-life

b. Greater methemoglobin production

c. Faster elimination

d. Higher acute toxicity

a. Longer biological half-life

Which toxicokinetic property contributes most to the persistence of nitrate in the body?

a. Retention and slow elimination

b. Extensive protein binding

c. Lipid accumulation

d. Enterohepatic recirculation

a. Retention and slow elimination

The primary mechanism responsible for hypoxia in nitrite poisoning is

a. Pulmonary edema

b. Methemoglobin formation

c. Bronchoconstriction

d. Respiratory depression

b. Methemoglobin formation

Nitrite-induced vasodilation may result in

a. Hypertension

b. Reduced coronary blood flow

c. Hypotension and collapse

d. Increased peripheral resistance

c. Hypotension and collapse

Nitrite poisoning may produce congestion because of

a. Arterial vasoconstriction

b. Venous blood stasis

c. Increased cardiac output

d. Polycythemia

b. Venous blood stasis

Which effect is characteristic of nitrite but NOT typically nitrate poisoning?

a. Irritation of gastrointestinal mucosa

b. Methemoglobinemia

c. Diarrhea

d. Salivation

b. Methemoglobinemia

A blood methemoglobin concentration of approximately 50% is generally associated with

a. Recovery

b. Mild intoxication

c. Terminal clinical signs

d. Chronic poisoning only

c. Terminal clinical signs

Which finding is most suggestive of acute nitrite poisoning?

a. Bright red blood

b. Brown-colored blood

c. Polycythemia

d. Hypercoagulability

b. Brown-colored blood

A herd experiencing abortions due to nitrate/nitrite exposure is most likely affected by

a. Maternal hypotension

b. Fetal hypoxia

c. Hyperglycemia

d. Hepatic failure

b. Fetal hypoxia

Chronic nitrate/nitrite poisoning may result in

a. Increased milk production

b. Enhanced immune function

c. Thyroid dysfunction

d. Polyuria

c. Thyroid dysfunction

Which post-mortem finding is most consistent with nitrite poisoning?

a. Severe gastrointestinal edema only

b. Brown poorly clotting blood

c. Renal mineralization

d. Pulmonary fibrosis

b. Brown poorly clotting blood

Severe erythema and edema of gastrointestinal mucosa is more characteristic of

a. Nitrite poisoning

b. Nitrate poisoning

c. Carbon monoxide poisoning

d. Organophosphate poisoning

b. Nitrate poisoning

The single most useful laboratory parameter for confirming nitrite poisoning is

a. ALT activity

b. Serum creatinine

c. Methemoglobin concentration

d. Blood glucose concentration

c. Methemoglobin concentration

A forage nitrate concentration above which value should raise serious concern?

a. 0.15%

b. 0.5%

c. 1.5%

d. 5%

c. 1.5%

Why may rumen lavage be beneficial in severe nitrate poisoning?

a. It increases methemoglobin reductase activity

b. It reduces ongoing microbial nitrite production

c. It enhances renal excretion

d. It decreases nitrate absorption from blood

b. It reduces ongoing microbial nitrite production

The therapeutic effect of methylene blue is primarily related to

a. Increased oxygen delivery

b. Enhanced NADPH-dependent methemoglobin reduction

c. Inhibition of nitrate absorption

d. Prevention of vasodilation

b. Enhanced NADPH-dependent methemoglobin reduction

Administration of excessive methylene blue may

a. Be completely harmless

b. Initially worsen clinical signs

c. Prevent methemoglobin formation entirely

d. Cause severe hypoglycemia

b. Initially worsen clinical signs

Which nitrosamine is considered the most toxic?

a. DENA

b. DMNA

c. Both are equally toxic

d. Toxicity depends only on dose

b. DMNA

Elevated nitrate concentration in water is most likely associated with

a. Deep wells supplied by water from fertilized fields

b. Water contaminated with animal waste

c. Water contaminated with decaying organic matter

d. All of the above

d. All of the above

Which factor may increase nitrate concentration in forage?

a. Fragmentation

b. Mold development during storage

c. Both a and b

d. Neither

c. Both a and b

Arrange species from highest to lowest susceptibility to nitrite poisoning

a. Bo > Ov > Eq > Su/Ca/Fe

b. Su/Ca/Fe > Eq > Ov > Bo

c. Eq > Bo > Ov > Su/Ca/Fe

d. Ov > Eq > Bo > Su/Ca/Fe

b. Su/Ca/Fe > Eq > Ov > Bo

The most efficient pathway for methemoglobin reduction is

a. Glycolysis

b. Pentose phosphate pathway

c. Krebs cycle

d. β-oxidation

b. Pentose phosphate pathway

Nitrite intoxication may directly cause

a. Bronchoconstriction

b. Smooth muscle relaxation within the gastrointestinal tract

c. Increased gastrointestinal motility

d. Urinary retention

b. Smooth muscle relaxation within the gastrointestinal tract

Which clinical sign is more characteristic of nitrate than nitrite poisoning?

a. Brown blood

b. Methemoglobinemia

c. Diarrhea and abdominal pain

d. Cyanotic mucous membranes

c. Diarrhea and abdominal pain

Nitrosamine formation is favored in

a. Alkaline conditions

b. Neutral conditions

c. Acidic conditions

d. Anaerobic conditions only

c. Acidic conditions