Toxicology Exam II Material Flashcards
What species is most susceptible to urea toxicosis?
Ruminants
What domestic species is most sensitive to ethylene glycol toxicity?
Cats
When is chelation therapy indicated in the case of iron toxicity?
Only in severe toxicosis within 12 hours of ingestion
Glycerol monoacetate (Monacetin) is an antidote for:
fluoroacetate
Which of the following chelators is most commonly used to treat acute zinc toxicosis?
- Succimer
- EDTA
- D-Penacillamine
- None of the above
none of the above
In canines, zinc levels fall very quickly after the source is removed. Chelation therapy is not typically used in the case of zinc toxicosis
T/F: Ionophore toxicity is associated with ↑ CPK, ↑ AST, ↑ LDH, and ↑ ALP
True
- Ionophore toxicity is associated with ↑ creatine phosphokinase (CPK), ↑ Aspartate transaminase (AST), ↑ Lactic dehydrogenase (LDH), and ↑ Alkaline phosphatase (ALP)*
- It is also associated with ↑ PCV*
Ingestion of a plant that has been sprayed with a 2,4-D herbicide may cause poisoning in livestock mainly because of accumulation of toxic levels of what toxicants?
Nitrate or cyanide
What is the treatment protocol for urea toxicosis in cattle?
Acetic acid or vinegar
Followed by a large volume of cold water. Normal saline for dehydration, and sodium bicarbonate IV for acidosis.
What is the mechanism of action (MOA) of pentachlorophenol (PCP) toxicosis?
Uncouples oxidative phosphorylation and blocks or decreases ATP
This leads to an increased oxygen demand in an effort to produce ATP. The oxygen demand is more than the oxygen supply, resulting in overheating, metabolic acidosis, and dehydration
T/F: Reduced cytochrome oxidase in cattle can be used as a diagnostic test in molybdenum toxicosis
True
What species is most susceptible to molybdenum toxicosis?
cattle
What species is the most sensitive to phenoxy derivatives of fatty acids (2,4-D herbicides)?
dogs
Describe the characteristic lesions associated with urea toxicosis
None
There are no characteristic lesions associated with urea toxicosis. However, dead animals are usually very bloated. The pH of the rumen would likely be very alkalotic. There may also be an ammonia odor
What chelator is typically used to treat copper toxicosis?
D-Penacillamine
Which of the following body systems is least likely to show clinical signs in chronic lead toxicosis?
- Renal systen
- Neurological system
- GI system
- Hematopoietic system
Renal system
In what breed do we typically observe chronic copper toxicosis?
Bedlington Terriers
This is due to an autosomal recessive disorder at 2-6 years of age
T/F: Hematologic signs including hemolytic anemia, icterus, and hemoglobinuria are commonly associated with zinc toxicosis
True
What are the preferred specimens for chemical detection of strychnine in a live animal?
stomach contents, bait, serum, urine
Serum and CSF (or ocular fluid) sodium concentrations above _______ mEq/L support diagnosis of water deprivation-sodium ion toxicosis
Serum and CSF (or ocular fluid) sodium concentrations above 160 mEg/L support diagnosis of water deprivation-sodium ion toxicosis
In what stage of acute iron toxicity do we expect to see the most serious clinical cardiovascular and metabolic effects?
Stage 3 (12-96 hours PI)
Vomiting, diarrhea, GI hemorrhage, metabolic acidosis, coagulation disorders, hepatic failure, cardiovascular collapse
T/F: Activated charcoal is highly effective for treatment of iron toxicity
False
Do younger patients have less or greater oral absorption of lead?
Greater
Younger patients have greater oral absorption of lead than adult patients. Younger patients are also more sensitive to lead toxicity because of their immature BBB.
T/F: Anorexia is a common clinical sign associated with arsanilic acid toxicosis in swine
False
Anorexia IS a clinical sign associated with arsanilic acid toxicosis in poultry
T/F: Onset of clinical signs of paraquat toxicity typically occur very rapidly
False
Signs may not be observed until 3 days after exposure to paraquat
Serum iron values above _______ mcg/dL are consistent with iron toxicity
> 300 mcg/dL
T/F: Cats that recover the acute phase of metaldehyde toxicosis develop liver failure within 2-3 days of exposure
False
DOGS that recover the acute phase of metaldehyde toxicosis develop liver failure within 2-3 days of exposure.
This has not been reported in cats
T/F: Enlarged yellow liver, enlarged friable and hemorrhagic kidneys, enlarged black spleen, and red wine-colored urine are lesions most likely associated with acute copper toxicosis
False
Enlarged yellow liver, enlarged friable and hemorrhagic kidneys, enlarged black spleen, and red wine-colored urine are lesions most likely associated with chronic copper toxicosis
T/F: Clinical signs of subacute selenium toxicosis in pigs are generally similar to toxicosis with arsanilic acid
True
What clinical signs predominate in the dog in the case of fluoroacetate (Compound 1080) toxicosis?
CNS stimulation and GI signs
T/F: Metaldehyde toxicity is associated with metabolic alkalosis
False
Metaldehyde toxicity causes metabolic acidosis
The most likely pathognomonic evidence of water deprivation/sodium ion toxicosis in swine is:
eosinophilic meningoencephalitis
This is only present in pigs and is only present during the first 24 hours!
What species is most sensitive to strychnine toxicity?
Horses, Cattle, Pigs
The toxic dose for these species is ~0.5 mg/kg. However, it is important to remember that while dogs are less sensitive (Toxic dose = 0.5 - 1.2 mg/kg), dogs are most frequently poisoned.
T/F: Methylene blue IV is the antidotal treatment for 2,4-D
False
Methylene blue IV is the antidotal treatment for nitrates
For treatment of seizures associated with metaldehyde toxicity, why is phenobarbital recommended after initial control with diazepam?
enzyme induction
Phenobarbital is an enzyme inducer, so it may also accelerate elimination of the toxin
What rodenticide has a characteristic acetylene odor?
Zinc Phosphide
What organic arsenical is mainly used as a feed additive in poultry?
Roxarsone
What signs are typically associated with acute paraquat toxicosis?
vomiting, anorexia, CNS depression
High doses may cause ataxia, dyspnea, and seizures. Signs may not be observed until 3 days after exposure
A dog presents to your clinic with compulsive hypermotility, abdominal pain, and vomits (the vomit smells like dead fish). Which of the following would you include in your treatment?
- Antacids
- Activated charcoal
- Ammonium chloride
- Methionone IV
antacids, activated charcoal
- If the GI contents smell like dead fish, you’re likely dealing with Zinc Phosphide toxicity. Antacids are administered because acid enhances toxicity (leads to hydrolysis to phosphine gas - occurs at pH 4 and lower).*
- The efficacy of activated charcoal isn’t super well documented but what the hell; why not*
T/F: The diagnosis of lead toxicosis in dogs is best established on the basis of the occurrence of basophilic stippling of erythrocytes
False
Basophilic stippling may occur on erythrocytes in dogs and rabbits associated with lead toxicity, but the best diagnostic sign is presence of lead in the blood
Approximately how long does strychnine persist in the environment?
Up to ~40 days
What species is most sensitive to monensin toxicosis?
Horses
Ionophores are rapidly metabolized by P-450 oxidative demethylation enzymes in the liver and excreted mainly in bile. Horses have the lowest levels of oxidative demethylases out of the other domestic species, so the compound is metabolized slowly
T/F: Arsanilic acid may produce peripheral and optic nerve degeneration
True
Which is more toxic: pentavalent arsenic or trivalent arsenic?
Trivalent arsenic
- Inorganic trivalent is more toxic than pentavalent, which is more toxic than organic*
- Trivalent > Pentavalent > Organic*
In what organs do we observe the most rapid accumulation and turnover of zinc?
pancreas, liver, kidney, spleen, male reproductive organs
T/F: Blindness may develop with arsanilic acid as well as with roxarsone
False
Blindness may develop with arsanilic acid but not with roxarsone
A feedlot steer that survived an overdose of monensin in the feed was found dead 3 weeks later.
T/F: The most likely cause of death, if related to the monensin toxicosis is persistent depolarization and arrhythmias as a result of the sodium and calcium channel effects
False
The most likely cause of death in this case, if related to the monensin toxicosis is cardiac fibrosis and insufficiency as a result of cardiac muscle necrosis during acute monensin toxicosis
What sample do you think is most appropriate for antemortem testing for lead toxicosis?
- Serum
- Plasma
- Whole Blood
- Brain tissue
Whole Blood
- > 90% of circulating lead is bound to erythrocyte membranes*
- Blood lead more than 0.4 ppm along with clinical signs is considered diagnostic (Blood lead >0.6 ppm are considered diagnostic regardless of correlation with clinical signs)*
The specimen of choice for analysis of nitrate poisoning in an animal that has been dead for several hours is:
ocular fluid
Brain sodium concentrations above _______ ppm support diagnosis of water deprivation-sodium ion toxicosis
Brain sodium concentrations above 2200 ppm support diagnosis of water deprivation-sodium ion toxicosis
Disruption of the citric acid cycle by inhibition of the aconitase enzyme is the mechanism of action for what toxicant?
Fluoroacetate
What is the most efficient chelator for binding lead?
Calcium disodium EDTA
- It is diluted and given in multiple doses IV (Used IM or SQ in large animals - painful!). Treat for a maximum of 5 days (renal injury is primary concern)*
- Make sure to remove and lead from the gut before chelation, as chelation may enhance absorption further*
- Or mayonnaise?*
Fomepizole (4-methyl pyrazole) is not recommended for treatment of ethylene glycol poisoning in cats because it causes methemoglobinemia and Heinz body anemia
False
It does not do those things
What is the mechanism of action for strychnine?
Blocks the post-synaptic effect of glycine in the spinal cord
- Glycine is an important inhibitory neurotransmitter to motor neurons and interneurons in the spinal cord/brainstem/thalamus*
- This leads to highly exaggerated reflex arcs, muscle spasms, severe extensor rigidity, and tonic seizures*
Washing samples for laboratory diagnosis is generally contraindicated, however in __________ toxicosis it is recommended
selenium toxicosis
Specimens in chronic toxicosis are hair and hoof and must be washed before analysis
T/F: You’re more likely to see reticulocytosis associated with zinc toxicity than with lead toxicity
True
T/F: Toxicity of paraquat is enhanced by selenium-vitamin E deficiency, depletion of tissue glutathione, and oxygen therapy
True
T/F: Seizures associated with strychnine toxicosis and water deprivation/sodium ion toxicosis are elicited by external stimuli
False
- Seizures associated with strychnine toxicosis are elicited by external stimuli.*
- Seizures associated with water deprivation/sodium ion toxicosis are not elicited by external stimuli!!*
What is the common name for the poisonous plant Senna occidentalis?
Coffee Senna
T/F: Cats are more sensitive to metaldehyde toxicosis than dogs
True
Cats are more sensitive than dogs, but dogs are more likely to ingest
T/F: Oxygen therapy is used in severe cases of paraquat toxicity
False
Oxygen is contraindicated because it may increase lung damage
T/F: Arsenic increases biliary excretion of selenium
True
A patient with suspected toxin exposure presents to your clinic and vomits. The vomitus has a fishy/garlic/acetylene odor to it. You open the windows and ventilate the room immediately because you suspect this is what toxin?
Zinc phosphide
Toxicity of urea is due to:
ammonia
Ammonia inhibits citric acid cycle resulting in lack of energy and decreased cellular respiration and tissue damage
T/F: Urea toxicosis is associated with ↑ ammonia, ↑ blood urea nitrogen (BUN), ↑ blood glucose, ↑ blood lactate, ↑ blood pH, ↑ transaminases (ALT, AST), and ↑ PCV
False
Urea toxicosis is associated with ↑ ammonia, ↑ blood urea nitrogen (BUN), ↑ blood glucose, ↑ blood lactate, ↑ transaminases (ALT, AST), and ↑ PCV
Urea toxicosis is NOT associated with ↑ blood pH. Blood pH will decrease due to the circulating acids.
Rumen pH is expected to increase (>7.5 is highly suggestive of urea toxicosis)
What is the mechanism of action of ionophore toxicosis?
Disruption of transmembrane electrochemical gradients
The main targets are the mitochondria of highly energetic tissues (myocardium, skeletal muscles, and the kidney)
T/F: The clinical signs associated with water deprivation/sodium ion toxicosis in swine are thought to be mainly caused by cerebral edema and overhydration of nerve cells
True
What is the drug of choice for treatment of mycoplasmosis in large animals?
Tetracycline
If Tetracycline does not work, Tiamulin is a good alternative in large animals.
T/F: Ketamine may be used for treatment of strychnine toxicity
False
In general, you want to avoid dissociative anesthetics in the case of strychnine toxicity
What is the principle behind chelation therapy?
The chelator binds a metal and forms a complex that is excreted
What is the primary transport protein for iron?
transferrin
When would you expect to observe respiratory signs associated with paraquat toxicity?
2-7 days
Respiratory signs include tachypnea, dyspnea, harsh respiratory sounds, cyanosis, and reduced pulmonary compliance
What abnormal coloration of the urine may be considered normal in a patient that is undergoing chelation therapy with Deferoxamine?
reddish-brown
What is the most toxic form of selenium?
Organic selenium in plants
Whereas synthetic organoselenium compounds are the least toxic
What species is most frequently affected by marijuana toxicosis?
Dogs
Cats are also susceptible
T/F: Repeated exposure to small amounts of strychnine over time is more toxic than a large single exposure
False
Most of the toxin is eliminated within ~24 hours and it does not accumulate in any particular tissue
What is the chelating agent of choice for inorganic arsenic?
Dimercaprol (BAL)
T/F: Fomepizole (4-methyl pyrazole) is used in the treatment of ethylene glycol in dogs and cats and acts by competitive inhibition of alcohol dehydrogenase
True
Alcohol dehydrogenase is the enzyme that catalyzes the initial steps in the metabolism of ethylene glycol and methanol to their toxic metabolites
What is the mechanism of action (MOA) of trivalent arsenic?
Binds to 2-SH groups of lipoic acid
This binding results in inhibition of glycolysis and the citric acid cycle
What toxicant is most likely to cause degeneration & pale areas in the myocardium and skeletal muscles, as well as damage in liver & kidney in most species?
Monensin
What signs should you expect to see in Stage I acute iron toxicosis?
Nausea, vomiting, diarrhea, GI hemorrhage
Which of the following metal toxicoses causes inhibition of the activity of several enzymes in heme synthesis?
- iron
- zinc
- inorganic arsenic
- lead
lead
What are the preferred specimens for post-mortem chemical detection of strychnine?
stomach contents, liver
What species is most susceptible to cocaine toxicosis?
Dogs
Especially police dogs
T/F: Sucralfate may be used in the treatment of iron toxicity
True
Sucralfate is a GI protectant
Methylene blue IV is the antidotal treatment for
Nitrate
T/F: In chronic organic arsenical (Arsanilic Acid) toxicosis in swine, there is gradual onset of blindness and partial paralysis, but pigs still eat and drink
True
How quickly would you expect to observe clinical signs associated with urea toxicosis?
0.5 - 3 hours (rapid onset)
Signs include restlessness, aggression, muscle tremors, salivation, teeth grinding, colic, bloat, rumen stasis, sternal recumbency while standing on the hind limbs, usually no diarrhea, convulsions and death within 1-2 hours
Animals less than one year old are more sensitive to nonprotein nitrogen (NPN) toxicosis, but animals of what age are more tolerant?
Animals less than one year old are more sensitive to nonprotein nitrogen (NPN) toxicosis, but very young animals (3-6 weeks) are more tolerant
Generally animals can tolerate more than _____% salt in feed as long as they have free access to water
Generally animals can tolerate more than 10% salt in feed as long as they have free access to water
T/F: With regard to the toxicokinetics of monensin, ruminants absorb ~50% of the toxin, whereas horses/monogastrics absorb ~100%
True
T/F: Ionophore toxicity is associated with ↑ serum Ca2+ and K+
False
Ionophore toxicity is associated with ↓ serum Ca2+ and K+
Chronic diarrhea, depigmentation, emaciation, and lameness in cattle suggests toxicosis with:
- inorganic arsenic
- lead
- molybdenum
- copper
- zinc
molybdenum
Signs manifested in propylene glycol toxicity are due to the accumulation of __________ acid, resulting in metabolic acidosis
D-Lactic Acid
L-lactic acid is used by the TCA cycle. D-lactic acid is not readily used and accumulates. High concentrations of D-lactic acid may cause lactic acidosis
What toxicant is associated with elevated citrate levels in the blood and kidneys?
Fluoroacetate
What clinical signs predominate in the horse in the case of fluoroacetate (Compound 1080) toxicosis?
cardiac signs
The most common source of lead toxicosis in animals is:
lead-based paints
A thumbnail sized chip of lead-based paint may contain 50-200 mg of lead. WOAH.
What species is most sensitive to fluroacetate toxicity?
Dogs
- Dogs: LD50 = 0.06 - 0.2 mg/kg*
- Cats: LD50 = 0.5 mg/kg*
- Livestock: LD50 = 0.15-0.7 mg/kg*
- Rodents: LD50 = 5-8 mg/kg*
What clinical signs predominate in cats and pigs in the case of fluoroacetate (Compound 1080) toxicosis?
CNS and cardiac signs
The presence of an odor of rotten garlic in a fresh carcass is suggestive of acute __________ toxicosis
selenium
T/F: Fomepizole is used in the treatment of both ethylene glycol and propylene glycol
False
Fomepizole is only used in the treatment of ethylene glycol
Identify this selenium indicator plant that is grown widely in the west:
Prince’s Plume
Stanleya pinnata
T/F: Phenothiazines may be used for treatment of strychnine toxicity
False
In general, you want to avoid opioids, phenothiazines, neuromuscular blockers, and dissociative anesthetics in treatment of strychnine toxicity
T/F: Tonic-clonic convulsive seizures and opisthotonos are the most predominant signs associated with Fluoroacetate (Compound 1080) toxicity in the horse
False
Cardiac signs predominate in the horse. Signs of heart failure, staggering, and arrhythmias may be seen as well as colic and terminal convulsions (from cerebral anoxia). Death may be due to arrhythmias or respiratory failure/anoxia
Deferoxamine is the chelating agent of choice for:
iron
Acute zinc phosphide toxicity is mostly due to:
phosphine gas
When zinc phosphide is exposed to acid, phosphine gas (PH3) is released. The gas is toxic, flammable, and is an irritant.
Other than freezing, what compound may be used to preserve the rumen for laboratory diagnosis in the case of suspected urea toxicosis?
Mercury chloride
T/F: Diets low in energy and protein but high in fiber will increase urea toxicity
True
Which of the following heavy metals require special royal-blue top tube for accurate measurement?
- Iron
- Zinc
- Lead
- Inorganic Arsenic
Zinc
What organic arsenical is mainly used as a feed additive in swine?
Arsanilic acid
T/F: Chronic selenium exposure results in high concentrations in the hair and hooves
True
A dog that is showing autonomic signs including vomiting, colic, diarrhea, mydriasis, dyspnea; nervous signs including convulsions; locomotor signs including ataxia; then recovers to show signs of liver failure and metabolic acidosis 2-3 days later is most likely intoxicated with:
Metaldehyde
A dog showing gastrointestinal signs followed by a phase of apparent recovery, which deteriorates into multi-organ failure is most likely poisoned with oral
iron
Sternal recumbency while standing on the hind limbs is a clinical sign of what food and water related toxicant?
NPN (Urea)
Signs include restlessness, aggression, muscle tremors, salivation, teeth grinding, colic, bloat, rumen stasis, sternal recumbency while standing on the hind limbs, usually no diarrhea, convulsions and death within 1-2 hours
T/F: If your favorite pig is pivoting on one foot, that behavior is pathognomonic for water deprivation-sodium ion toxicity
False
Pivoting on one foot is considered characteristic, but NOT pathognomonic
When would you expect to see late signs associated with ethylene glycol toxicity in the cat?
12-24 hours post-ingestion
When would you expect to see late signs associated with ethylene glycol toxicity in the dog?
24-72 hours post-ingestion
What drug is considered the “most nephrotoxic drug ever”?
Amphotericin B
- “But that’s not important”*
- Yes it is. Use of this drug is a differential diagnosis for ethylene glycol toxicosis.*
T/F: Ethylene glycol is known to cause heinz body anemia in cats
False!
Propylene glycol is known to cause heinz body anemia in cats
….dummy
