10. Toxicants Affecting the Cardiac & Respiratory Systems II

What are two important plants that are part of the solanaceae family?

jimsonweed and deadly nightshade

What toxic principles are in the solanaceae family?

hyoscyamine, scopolamine, and atropine

What is the mechanism of toxicity of the solanaceae family?

muscarinic antagonist (block acetylcholine from getting to the muscarinic receptor)

When does death camas poisoning often occur?

early spring when other vegetation is less available

What is the toxic agent of death camas zigadenus spp?

zigacine (steroidal alkaloid)

What is death due to when it comes to death camas poisoning?

severe vasodilation, bradycardia, cardiac necrosis, and CNS involvement

What amount of death camas is fatal to sheep? What can be said about treatment?

1.5 gm/kg; rarely successful

What is the toxic principle of white snakeroot ageratina spp? What is the principle toxic agent?

tremetol; tremetone

How does tremetone produce toxicity?

must be activated by microsomal enzyme to produce toxicity

Tremetone toxic agents are found in ________.

milk

When will clinical signs of tremetone toxicity appear in sheep, cattle, and horses?

after consumption of 0.5 to 1.5% body weight of the green plant material

High levels of what mycotoxin may cause fatal pulmonary edema in pigs 1-4 hours after exposure?

fumonisin

toxic gas that is irritating to upper airways, with peak symptoms at 30-90 minutes

chlorine/chloramine

prepared by the reaction of ammonia with sodium hypochlorite

chloramine

At greater than what level will ammonia irritate the eyes and respiratory mucous membranes, increase the incidence and intensity of microbial or parasitic infections and reduce growth rates?

100 ppm

True or false: High levels of ammonia found in poultry houses have about the same level of toxicity to birds as they would to other animals.

true

True or false: There are background levels of about 0.02 ppm in rural areas, 13 ppm in urban areas, nd 40 ppm in areas of high urban traffic.

true

In humans, what percent CO-Hb is considered normal?

3%

In humans, what percent CO-Hb causes drifting of attention?

6-8%

In humans, what percent CO-Hb causes headaches?

10-20%

In humans, what percent CO-Hb causes dizziness?

20-30%

In humans, what percent CO-Hb causes tachypnea, tachycardia, and confusion?

30-60%

In humans, what percent CO-Hb causes fatality?

60%

What species response more acutely to carbon monoxide than mammals? What have been used as sentinels for miners?

birds; canaries

Methane becomes an asphyxiant at what percent? It is an explosion hazard at what percent?

85%; 10-15%

What is hydrogen sulfide’s greatest danger to animals and humans?

ability to paralyze the respiratory tract

Above what levels is hydrogen sulfide going to kill a mammal?

500-2000 ppm

Hydrogen sulfide is ________ than air and ________ in the water of manure pits.

heavier; insoluble

Humans and presumably animals can detect hydrogen sulfide at what level?

0.025 ppm

True or false: Exposure of caged birds to gases released from overheated non-stick cookware has been shown to result in a high percentage of deaths, with findings of pulmonary edema and hemorrhages. Under normal cooking conditions, PTFE-coated cookware is stable and safe. Many studies have found that PTFE-coated pans must be heated to above 536 deg F to release toxic particles and fumes, in a reaction called pyrolysis.

true

What is the toxic principle of poison hemlock concium maculatum?

N-methyl coniine, coniine (pyridine alkaloids)

What is the mechanism of action of poison hemlock?

block neuromuscular junctions

What is the toxic dose of poison hemlock?

0.1 g

What are the symptoms of poison hemlock toxicity?

R
P
R

• rapid progressive muscle weakness

• paralysis

• respiratory failure

What is the toxic principle in water hemlock?

cicutoxin

What is the mechanism of action of water hemlock?

inhibition of GABAergic receptors, similar to strychnine

What are the signs of water hemlock toxicity?

tremors followed by seizures culminating in respiratory failure

True or false: Typically, ABPEE occurs in the fall, 5-10 days after change to a better, often lush, pasture. A similar condition has been reported when cattle are fed on a wide variety of grasses, alfalfa, rape, kale, and turnip tops.

true

What are the main metabolites involved in ABPEE?

metabolites of the naturally occurring amino acid L-trypthophan

What is L-tryptophan degraded to? What is that converted to by some ruminal microorganisms?

indoleacetic acid; 3-methylindole

____-________ is absorbed into the bloodstream and is the source of pneumotoxicity after metabolism by the mixed function oxidase system, which is very active in the lungs.

3-methylindole

this plant causes more cattle deaths in Tennessee than any other toxic plant and is very poisonous to cattle and other ruminants, as well as horses

perilla mint perilla frutescens

What is the toxic principle in perilla mint?

perilla ketone

It is common for sweet potatoes to be infested with what?

fusarium solani creating pneumotoxin 4-ipomeanol

What is the mechanism of toxicity of perilla mint and aflatoxin 4-ipomeanol?

damage to the pulmonary endothelium and type 1 pneumocytes, resulting in a proliferation of type II pneumocytes which rapidly fill the lungs and cause acute interstitial pneumonia that is frequently fatal

What will ingestion of perilla mint and aflatoxin 4-ipomeanol cause?

acute bovine pulmonary emphysema and edema (ABPEE)

What are the signs of pneumonia associated with perilla ind and aflatoxin 4-ipomeanol characterized by?

acute onset of dyspnea and extension of the head and frothing from the mouth and nose

What families are considered cyanogenic plants?

prunus spp and sorghum spp

What are different examples of cyanogenic plants?

W
C
A
P
A
J
A
S

• wild cherry

• choke cherry

• apricot

• peach

• apple

• johnson grass

• arrow grass

• sudan grass

What are the most common toxic principles in cyanogenic plants?

amygdalin and prunasin

What are the toxic compounds of cyanogenic plants readily converted to in the GI tract and absorbed?

HCN

True or false: Enzymatic conversion of the cyanogenics is greater when plant cells are damaged as occurs when the leaves are crushed, chewed, frozen, or wilted. The pH of the ruminant GI and greater water content favors conversion to HCN.

true

What is the mechanism of toxicity of the cyanogenic plants?

HCN has a high affinity for Fe3+ in cytochrome oxidase

Chronic cyanide poisoning from ingestion of low levels of HCN may cause ________ and may even be ________.

neutrotoxicity; goitrogenic

What is the onset of clinical signs like when it comes to cyanogenic plants?

peracute

How will venous blood appear with HCN toxicity?

blood will appear a bright cherry red

What is the treatment for cyanide toxicity? What does it do?

sodium nitrite; converts some hemoglobin to methemoglobin, which binds cyanide

What are examples of plants that contain nitrates?

R
L
J
S
S
D

• redroot pigweed

• lamb’s quarters

• johnson grass

• sudan grass

• sorrel

• dock

What are examples of crops that contain nitrates?

O
C
W
A
S
S

• oats

• corn

• wheat

• alfalfa

• sugar beet

• soybean

What conditions cause increased nitrate content in plants?

D
E
E
E
F
E

• drought followed by rain

• extremes of temperature

• extended cloudy conditions

• frost

• excessive nitrate fertilizer (rapid growth)

True or false: In normal growth conditions, nitrate does not build up in the plant because the stem and leaves normally convert nitrate to protein as fast as it is taken up by the roots. Under certain conditions, the balance is disrupted and the roots will accumulate nitrate faster than the plant can convert it.

true

What is the toxic principle when it comes to plants containing nitrates?

nitrate which is reduced to nitrite

What is the mechanism of toxicity for plants containing nitrates?

nitrite combines with hemoglobin and oxidizes it to methemoglobin (Fe3+)

What can reduce methemoglobin to hemoglobin? Except for when?

methemoglobin reductase; when the production of methemoglobin is too high or the reductase activity is too low

What is the primary symptom of nitrite intoxication? What is it indicated by? What will follow within several hours if untreated?

anoxia (tachypnea and cyanosis); rapid heart rate, tremors, weakness, coma/convulsions and death

How will a blood sample appear with nitrite toxicity?

chocolate brown

What test can be used to indicate the presence of nitrate?

diphenylamine color change test

What is the treatment for nitrite toxicity?

A
M

• animals should be removed from the source and fed a low nitrate feed (hay) and maintain a quiet enviornment

• methylene blue

dye that concerts methemoglobin to hemoglobin, restoring oxygen carrying capacity

methylene blue

Leaves of acer rubrum (red maple), especially when wilted in the fall, will cause what, specifically in horses?

severe oxidative damage to equine RBCs, leading to potentially fatal methemoglobinemia

What toxic compounds have been implicated as the toxic compounds responsible for red maple toxicosis?

gallic acid, pyrogallol, and tannins

What are the symptoms of red maple toxicosis?

R
T
W
C
D

• rapid heart rate

• tremors

• weakness

• coma/convulsions

• death

In red maple toxicosis, how will the blood sample appear?

chocolate brown