Toxic Plants - 2

Question 1

Describe the mechanism of action of anthraquinones

Answer 1

• purgative
• coffee weed causes skeletal and cardiac muscle degeneration
• urine may be coffee colored due to myoglobinuria
• horses usually die from liver failure

Question 2

Describe the mechanism of action of calcinogenic glycoside

Answer 2

• hypercalcemia
• calcification of the elastic tissues of the arteries, tendons, and ligaments
• increased density of bones causing lameness

Question 3

Describe the mechanism of action of carboxyatractyloside

Answer 3

• hepatotoxicity
• excessive salivation
• renal damage and hypoglycemia

Question 4

Describe the mechanism of action of cardiac glycosides

Answer 4

cardiotoxic by inhibiting Na/K ATPase

Question 5

Describe the mechanism of action of coumarin glycosides

Answer 5

• form dicoumarol in spoiled plants
• hemorrhage due to antagonism of vitamin K by inhibiting vitamin K epoxide reductase resulting in deficiency of coag factors II, VII, IX, and X

Question 6

Describe the mechanism of action of cyanogenic glycosides

Answer 6

• inhibition of cytochrome oxidase and inhibition of cellular respiration
• vasoconstriction
• inhibition of glycolysis
• inhibition of citric acid cycle
• irritation of mucus membranes
• chronic: neuronal degeneration and antithyroid

Question 7

Describe the mechanism of action of cycasin

Answer 7

• causes GI irritation and liver damage
• teratogenic, mutagenic, and carcinogenic
• BMAA is neurotoxic
• unknown toxin causes neuronal degeneration in CNS

Question 8

What are the clinical signs of cycasin?

Answer 8

• GI and liver disease, or ataxia and CNS
• dogs show GI and liver damage
• sheep show GI signs and weight loss
• cattle show neuronal signs

Question 9

Describe the mechanism of action of glucosinolate

Answer 9

antithyroid

Question 10

Describe the mechanism of action of nitropropanol glycoside

Answer 10

inhibits enzymes of the krebs cycle and cellular oxidative phosphorylation

Question 11

What are the clinical signs of nitropropanol glycoside?

Answer 11

• respiratory and neurological signs in cattle and sheep (cracker heels or roaring)
• horses and rodents show neurologic signs

Question 12

Describe the mechanism of action of phytoestrogens

Answer 12

bind to estrogen receptors causing infertility

Question 13

What are the clinical signs of phytoestrogens?

Answer 13

• infertility in females

- decreased libido and feminization in males

Question 14

Describe the mechanism of action of protoanemonin

Answer 14

• a volatile oil released by hydrolysis of the glycoside

- causes severe irritation of GI mucosa and dermatitis

Question 15

Describe the mechanism of action of ptaquiloside

Answer 15

• death of the precursor cells in the bone marrow causing aplastic anemia in cattle and sheep
• neoplasm in urinary tract causing enzootic bovine hematuria
• tumors of the upper digestive tract and retinal degeneration in sheep

Question 16

What are the clinical signs of ptaquiloside toxicosis?

Answer 16

• aplastic anemia: anorexia, and hemorrhage

- enzootic hematuria: blood in urine, anemia, tachycardia, and death

Question 17

Describe the mechanism of action of steroidal plants

Answer 17

• liver damage and inability to eliminate phylloerythrin

- hepatogenic photosensitization

Question 18

Describe the mechanism of action of gossypol

Answer 18

• cardiotoxic and secondary liver damage
• reduces male fertility by destroying seminiferous tubules
• protein malnutrition, inhibits enzymes, and interferes with hemglobin synthesis

Question 19

Describe the mechanism of action of molybdenum

Answer 19

causes signs of copper deficiency

- watery diarrhea, wasting, anemia, depigmentation, demyelination, osteoporosis

Question 20

Describe the mechanism of action of copper

Answer 20

liver damage, hemolysis, and methemoglobinemia

Question 21

Describe the mechanism of action of selenium

Answer 21

acute: GI irritation and respiratory signs
chronic: hoof and hair abnormalities

Question 22

Describe the mechanism of action of nitrate

Answer 22

• GI irritation
• formation of methemoglobin
• resp insufficiency
• abortion

Question 23

Describe the mechanism of action of dimethyl disulfide

Answer 23

• 5-methyl cysteine sulfoxide is reduced by intestinal flora to dimethyl disulfide
• large amounts cause oxidation of RBCs to form heinz bodies

Question 24

What are the clinical signs of dimethyl disulfide toxicosis?

Answer 24

anemia, depression, hemoglobinemia, hemoglobinuria, icterus, and cyanosis

Question 25

Describe the mechanism of action of diterpene esters

Answer 25

- direct irritation of skin and mucus membranes | - activate protein kinase C resulting in cell damage and enzyme disfunction

Question 26

What are the clinical signs of diterpene ester toxicosis?

Answer 26

- irritation and blistering of the skin and GI mucosa | - salivation, vomiting, and diarrhea

Question 27

Describe the mechanism of action of grayanotoxins

Answer 27

- bind to sodium channels in nerves, skeletal muscles, cardiac muscles, and CNS - increase permeability of sodium ions - irritation of GI mucosa

Question 28

What are the clinical signs of grayanotoxins?

Answer 28

- salivation, vomiting, colic, diarrhea - depression, tachycardia, tachypnea, seizures, fever - death due to aspiration pneumonia

Question 29

Describe the mechanism of action of lectins

Answer 29

- ricin and abrin are glycoproteins | - inhibit cellular protein synthesis resulting in cell death

Question 30

What are the clinical signs of lectin toxicosis?

Answer 30

hemorrhagic gastroenteritis

Question 31

Describe the mechanism of action of meliatoxins

Answer 31

enterotoxic and neurotoxic

Question 32

What are the clinical signs of meliatoxins?

Answer 32

- GI signs - CNS and peripheral neuronal signs - death from respiratory failure

Question 33

Describe the mechanism of action of propyl disulfide

Answer 33

- disulfides produce oxygen free radicals which damage RBC membranes - also cause denaturation of hemoglobin resulting in heinz bodies

Question 34

What are the clinical signs of propyl disulfide toxicosis?

Answer 34

anorexia, tachycardia, ataxia, tachypnea, dyspnea, icterus, anion odor, and abortion

Question 35

Describe the mechanism of action of tetradymol

Answer 35

- induction of microsomal enzymes | - liver damage that decreases elimination of phylloerythrin

Question 36

What are the clinical signs of tetradymol toxicosis?

Answer 36

- anorexia, depression, incoordination, dyspnea, icterus, and head pressing - skin swelling, erythema, necrosis, and sloughing

Question 37

Describe the mechanism of action of thiaminase

Answer 37

destroys thiamine in the diet and produces signs of deficiency in monogastric animals - neurotoxic

Question 38

Describe the mechanism of action of triterpenoid saponins

Answer 38

direct irritation of GI mucosa

Question 39

What are the clinical signs of triterpenoid saponin toxicosis?

Answer 39

salivation, anorexia, vomiting, diarrhea, colic, and hypothermia

Question 40

Describe the mechanism of action of resins or resinoids

Answer 40

irritation of the nervous or muscle tissue