Exam 2: Larkspur, Water Hemlock, Death Camas, Cardiotoxins, Lectins

Question 1

Larkspur: Be able to identify plant, Know mechanism of action, clinical signs, treatment, grazing management strategies.

Answer 1

Blue, has spurs on flowers!

Norditerpenoid alkaloids, Methyllycaconitine: Dominant MSAL-type, block nicotinic acetylcholine receptors at the neuromuscular junction.

sudden death – 3-4 hrs
Muscular weakness, Staggering gait, Rapid Heart Rate, Sternal then lateral recumbency, Death from neuromuscular paralysis and/or Bloat, No significant postmortem signs, Identify plant in rumen.

No proven treatment… Minimize stress: Place with head/chest uphill. Treat Bloat – stomach tube or Trocar. Acetyl Cholinesterase Inhibitors: Neostigmine (0.04 mg/kg iv). Stress of treatment may outweigh benefit. Grazing management: Place less sensitive animals in high-risk areas. Mineral salt supplements

Question 2

Water Hemlock: Identify plant, Toxin, Mechanism of action, Clinical Signs/Symptoms, treatment

Answer 2

white small flowers. grown around water. thick roots.
Cicutoxin. Unsaturated acetylenic alcohols - C17H22O2. Noncompetitive inhibitor of GABAA -(convulsions/seizures)

Respiratory failure. Violent convulsions within 10 -15 minutes, Violent chewing/ tongue biting, Bloat, Dilated pupils, Respiratory Failure. Pathological findings: Pale areas in heart and skeletal muscles
Myofiber degeneration, Elevated LDH, AST, and CK.

PREVENTION. graxing management. herbicides.
Treatment (unlikely)
Experimentally 20-77 mg/kg sodium pentobarbital IV at first seizure was effective in sheep.
Benzodiazepines (midazolam) and Barbiturates are recommended for treatment of poisoning in humans.

Question 3

Death Camas: Identify plant, Toxin, Clinical Signs/Toxic Mechanism

Answer 3

white flower, on a stalk, not in bunches like water hemlock. (has been mistaken as wild onion bulb)

Cevanine Steroidal Alkaloids. Alkaloids with hypotensive properties
Depolarize Na+ channels causing them to remain open resulting in hypotension and cardiovascular collapse, Dilate arterioles, Constrict veins, Irregular Heart Rate. no standard treatment. 2 mg of atropine sulfate and 8 mg picrotoxin per 100 lbs body weight may be effective.

Question 4

Yew: Identify plant, Toxins, Clinical signs

Answer 4

Looks like a green bush, can have red looking fruit on it.

Taxine A,B: Inhibits cardiac calcium & sodium channels. Taxane: Microtubule poison
A sudden onset of muscle trembling, incoordination, nervousness, difficulty in breathing, slow heart rate, vomiting, diarrhea, convulsions, and death are characteristic of yew poisoning in all animals. Sudden death may be the only observed sign in many cases. There are no post mortem lesions that are diagnostic of yew poisoning. no effective treatment.

Question 5

What is the mechanism of action for milkweed, foxglove?

Answer 5

a cardiac glycoside

By inhibiting the Na+/K+-ATPase, cardiac glycosides cause intracellular sodium concentration to increase. This then leads to an accumulation of intracellular calcium via the Na+-Ca++ exchange system. Calcium binds to troponin-C, which increases contractility (inotropy). This is the medicinal effect of the cardiac glycosides, but when pushed too far things go bad.

Question 6

What are clinical signs for milkweed toxicity?

Answer 6

Sudden death, Cardiac arrythmias and first and second degree heart block, Abdominal pain and diarrhea are common. Early symptoms: Rapid breathing, Cold extremities, Rapid, weak, irregular pulse.

Question 7

Describe 5 major treatment options.

Answer 7

Induce Vomiting
Oral activated charcoal
Cathartic
Monitor serum K+
IV fluids
Anti-arrythmic drugs: KCl, procainamide, lidocaine, atropine, K2EDTA

Question 8

What is the mechanism of action for grayanotoxins found in rhododendrons, azaleas?

Answer 8

also cardiac glycosie

Grayanotoxins- diterpenoids, Inhibit Voltage-gated Na channel, 0.2% body wt. leaves toxic/lethal, Honey is toxic to people

Question 9

What is the mechanism of action, clinical signs, and treatment options for lectins? List the 3 plants associated with lectin poisoning.

Answer 9

Plant glycoproteins that can bind to cell surface carbohydrates to facilitate entry into the cell and inhibit ribosomal protein synthesis. Clinical Signs (1-2 day lag period)
Initially, Pyrexia, Depression, Anorexia, Colic. Progress to vomiting, weakness, hemorrhagic Diarrhea.

Castor beans (Ricinus communis), Rosary pea (Abrus precatorius), Black Locust (Robinia pseudoacacia)