4.4 Lab - Toxic Plants cont.

Question 1

what type of liver toxins can be found in plants, and what plants are they found in?

Answer 1

Plants containing:
* Pyrrolizidine alkaloids (ragwort, houndstongue)
* Unknown hepatotoxins (alsike clover etc.)
* Amatoxins (cytotoxic mushrooms – will talk
about at end of the lab)
* Microcystins (blue-green algae/cyanobacteria – already discussed)

Question 2

what do Pyrrolizidine alkaloids do to the body?

Answer 2

Hepatotoxic, impairs cell division (megalocytosis)

Question 3

what type of toxin is found in ragwort? what does it do? what species does it affect? what are the clinical signs and lesions?

Answer 3

• Toxin: Pyrrolizidine alkaloids
• Species susceptible: cattle, horses
• Part of plant: All above ground parts
• Clinical signs:
• Acute: colic, tachycardia, death
• Chronic: photosensitization, weigh loss, liver failure, hepatic encephalopathy, jaundice, death
• Lesions: Chronic liver disease, fibrosis, bile duct proliferation, megalocytosis

Question 4

acute clinical signs of pyrrolizidine alkaloid toxicity?

Answer 4

• Acute: colic, tachycardia, death

Question 5

chronic clinical signs of pyrrolizidine alkaloid toxicity?

Answer 5

photosensitization, weigh loss, liver failure, hepatic encephalopathy, jaundice, death

Question 6

what type of toxin is found in red maple? what species is susceptible?

what clinical signs will we see?

Answer 6

• Toxin: gallic acid
• Species susceptible: horses
• Part of plant: wilted or dried leaves (older wilted leaves contain more than spring leaves!)
• C/S: depression, anemia, icterus, cyanosis, hemoglobinuria

Question 7

what is the pathogenesis of gallic acid? what lesions will we see?

Answer 7

gallic acid
> converted to PYROGALLOL in the ileum of the horse
> oxidation of hemoglobin
> produces methemoglobin and causes hemolysis with Heinz body formation
➝ anemia, icterus, hemoglobinuria
> periacinar hepatic necrosis; hemoglobinuric nephrosis

Question 8

What treatment can be offered to a horse that has eaten red maple and what is the prognosis? what should we watch out for?

Answer 8

• Supportive care; including intravenous fluids, blood transfusions, and oxygen therapy. - Because red maple leaf toxicity compromises the horse’s ability to carry oxygen in its blood, affected horses should be kept quiet in a stall while being treated.
• Secondary complication of red maple leaf toxicity is acute kidney failure due to the by- products of red blood cell breakdown (hemoglobin and methemoglobin)
• “hemoglobinuric nephrosis”

Question 9

plants that cause hemolysis, other than red maple. what is their mechanism and what is the result?

Answer 9

Onions (and garlic!)
* Allium spp.
* Dogs, cattle, others
* N-propyl disulfide: Oxidative damage to erythrocytes; Heinz bodies
* Hemoglobinemia, hemoglobinuria, anemia

Question 10

what type of toxins damage bone marrow and blood, and in what ways? what plants are these found in?

Answer 10

• Red blood cell membrane injury/hemolysis (*red
  maple, onions, Brassicas (turnips, kale, rapeseed))
• Myelosuppression (*bracken fern)
• Clotting abnormalities (mouldy sweet clover)

Question 11

what type of issues does bracken fern cause? what toxins does it contain? what species are susceptible?

Answer 11

Myelosuppression

Toxins:
* Type I thiaminase
* Ptaquiloside

Species susceptible:
* Cattle (neoplasia, bone marrow suppression)
* Horses (neurologic)
* Sheep (bright blindness)

• Part of plant: all, fresh or dry
• Not palatable, but will be eaten if no other forage available.

Karen’s way of remembering this toxin: Ptaquiloside sounds like it should suppress inhibitions, not bone marrow.

Question 12

clinical signs of braken fern consumption in cattle

Answer 12

• Fever, anorexia, anemia, leukopenia, thrombocytopenia, hemorrhages, melena
  (“bovine enzootic hematuria”)

Question 13

lesions associated with bracken fern consumption in cattle

Answer 13

• Generalized hemorrhage, anemia, aplastic marrow; abomasal ulceration
• Urinary bladder lesions – hemorrhage, inflammation, hyperplasia, papilloma, carcinoma or hemangioma in cattle exposed to lower doses for 1-6 years.

Question 14

what does bracken fern consumption cause in horses? what are the associated clinical signs and lesions?

Answer 14

• Thiamine deficiency d/t thiaminases
• Similar to Vit B1 deficiency, respond to thiamine therapy
• C/S: Weight loss, depression, weakness, incoordination (“bracken staggers”), wide stance, twitching, arrhythmias, recumbency, convulsions, death.
• Lesions: nonspecific, pericardial/epicardial hemorrhage

Question 15

types of nephrotoxins and plants that contain them:

Answer 15

• Oxalates (red-root pigweed, rhubarb)
• Tannins (oak)
• Unknown toxins (*lily, *grape)

Question 16

what species are susceptible to lily toxins? what are clinical signs? what are the lesions?

Answer 16

• Toxin: unknown
• Species susceptible: Cats
• C/S: Depression, vomiting, renal failure

Lesion: acute renal tubular necrosis
-kidney injury will lead to dehydration, further vomiting and finally reduced and then no urine production

Question 17

Treatment options for cats who ingest lilies? prognosis?

Answer 17

• Chances of survival are increased with aggressive decontamination and fluid diuresis within 18 hours of exposure
• Successful treatment includes initiation of fluid diuresis before the onset of anuric renal failure.
• Prognosis is excellent if fluid diuresis is started before anuric renal failure has developed.
• Once anuria develops, peritoneal dialysis or hemodialysis is the only potential treatment, and the cat will likely have chronic kidney failure

Question 18

what is a teratogen?

Answer 18

is any agent that causes an abnormality following fetal exposure during pregnancy.

Question 19

what are some examples of teratogenic plants?

Answer 19

• Milk vetches, locoweeds, lupines
• False hellebore

Question 20

what does false hellebore contain that is teratogenic? what animals does it affect? what are the clinical signs?

Answer 20

• Contains teratogenic alkaloids such as cyclopamine
• Sheep (and occasionally goats, alpacas and cattle) when ingested at day 14 gestation
• Often they do not abort and will retain the pregnancy until a stillbirth occurs
• Multiple clinical signs – called “monkey face“ lambs, holoprosencephaly, cyclopia, anopthalmia, cleft palate; shortened maxilla, arthrogryposis, shortened long bones
• Toxin causes interference with body patterning via sonic-hedgehog signaling.

Question 21

what are a some types of toxins that mushrooms can contain?

Answer 21

• Cytotoxins Most important
• Autonomic nervous system toxins
• Central nervous system toxins
• Gastrointestinal irritants

Question 21

what are a some types of toxins that mushrooms can contain?

Answer 21

• Cytotoxins Most important
• Autonomic nervous system toxins
• Central nervous system toxins
• Gastrointestinal irritants

Question 22

what type of toxins are found in cytotoxic mushrooms? what is mechanism? what are clinical signs and lesions?

Answer 22

eg Amanita phalloides, amanita verna
HIGH risk

• Toxin: cyclopeptide amatoxins
• Mechanism: inhibit RNA polymerase, block protein
  synthesis, signal apoptosis

C/S: Four phases
* Latent period 6-24 hours
* Severe GI signs – pain, vomiting, bloody diarrhea
* Second latent period mimicking recovery
* In 36-84 hours – fulminant hepatic, renal failure, death.

• Lesions: periacinar to massive hepatic necrosis, renal tubular necrosis

Question 23

what type of toxin does amanita muscaria contain?

Answer 23

Ibotenic acid, muscimol – act on two
major neurotransmitters of the central nervous system: glutamic acid and GABA
 Results in these have psychoactive toxic properties (hallucinations)

 Dogs can result in acute gastrointestinal distress that precedes a potentially life-threatening central neurologic syndrome characterized by seizures, tremors, and somnolence
 Dogs like to eat these because apparently they smell like fish