Toxicology Lecture 5 Neurotoxic Plants

Front 1

Few toxins have pathognomonic signs and in most cases you will discover ______ first.

Back 1

A damaged organ
-Differetials then include:
toxins that could cause this damage
-infectious cause
-other causes such as metabolic, allergic, nutritional

Front 2

How should you organize different toxins?

Back 2

Into systems effected

Front 3

What are 9 plants containing neurotoxins?

Back 3

1) Lupine
2) Larkspur
3) Locoweed
4) Yellow star thistle
5) Morning glory
6) Bracken fern
7) Poison Hemlock
8) Water Hemlock
9) Perennial rye grass

Front 4

Where is lupine located?

Back 4

Western U.S.

Front 5

What are the characteristics of lupine?

Back 5

-Legum
-5 petal flower
-Blue flower
-Raceme (stalk)
-Seed pod
-Palmate branch leaf

Front 6

What is the toxin in lupine?

Back 6

Quinolizidine alkaloids that have nicotinic effect

Front 7

Are all species of lupine toxic?

Back 7

No, most are not

Front 8

What part of the lupine plant contains the toxin?

Back 8

Leaf, steam, seed and seed pod

Front 9

Lupine is toxic in dry ______.

Back 9

Dry hay

Front 10

Lupine is toxic at <____% of body weight, or less if eaten for 3-4 days.

Back 10

1%

Front 11

True or false. Lupine can be passed in the milk.

Back 11

True

Front 12

Lupine is more concentrated and palatable in ____ stage.

Back 12

Seed stage

Front 13

Are sheep or cattle more commonly affected by lupine?

Back 13

sheep

Front 14

What are the 3 toxic principles of lupine?

Back 14

1) Hepatotoxic (mycotoxin)
2) Crooked calf (anagyrine)
3) Lupinine alkaloid (neurologic signs)

Front 15

What are the 3 neurologic signs of lupine?

Back 15

1) Seizures
2) Ataxia, head pressing
3) Salivation

Front 16

What is the mode of action of the lupine toxin?

Back 16

Stimulates nicotinic acetylcholine receptors
-Neuromuscular
-Autonomic: sympathetic & parasympathetic

Front 17

What are the 5 clinical signs of lupine toxicity?

Back 17

1) Salivation
2) Ataxia
3) Muscle twitching
4) Seizures
5) Head pressing, excitement, nervous
-Also causes crooked calf syndrome and hepatotoxicity due to a mycotoxin

Front 18

What are 4 differential diagnoses for lupine?

Back 18

1) Other neurotoxic plants
2) Neurotoxic chemicals
-Lead
-Organic- phosphate
3) Cerebral abscess
4) Meningitis (listeria)
5) Rabies

Front 19

How do you diagnose lupine toxicity?

Back 19

Identify plant being eaten
-No specific clinical pathology changes
-No visible lesions on postmortem
-Test for alkaloid in blood or urine (not readily available)

Front 20

What is the treatment for lupine toxicity?

Back 20

No specific antidote
Prevent, don't graze

Front 21

What are the characteristics of larkspur (delphinium sp.)?

Back 21

Perennial, alternate leaves, palamate veins and lobes, divided pointed leaves, flowers on terminal racemes, usually 5 blue petals

Front 22

What are the 2 types of larkspur?

Back 22

Low and tall
-Tall= at higher elevations E

Front 23

Where is larkspur located?

Back 23

On western ranges
Grows in undisturbed soil in pastures

Front 24

What part of a larkspur plant is toxici?

Back 24

All parts or toxic
Highest in leaves, young plant

Front 25

What larkspur plants are more concentrated?

Back 25

The green growing plant and seed
-May, June

Front 26

Larkspur is palatable to _____.

Back 26

Cattle

Front 27

What are the 2 types of larkspur?

Back 27

Tall larkspur
Low larkspur

Front 28

What is the "window" for tall larkspur toxicity?

Back 28

Early flowering---> seed pod

Front 29

Do sheep or cattle tend to get tall larkspur when the toxin is highest?

Back 29

Cattle-they eat more after a rain storm, sheep avoid it when the toxin is highest

Front 30

When is low larkspur most toxic? To what animal?

Back 30

Eaten in early spring before flowing - when most toxic and tasty to cattle

Front 31

What type of toxin is present in larkspur?

Back 31

Polycyclic diterpene alkaloids

Front 32

What are the 2 types of larkspur?

Back 32

Tall larkspur
Low larkspur

Front 33

What is the "window" for tall larkspur toxicity?

Back 33

Early flowering---> seed pod

Front 34

Do sheep or cattle tend to get tall larkspur when the toxin is highest?

Back 34

Cattle-they eat more after a rain storm, sheep avoid it when the toxin is highest

Front 35

When is low larkspur most toxic? To what animal?

Back 35

Eaten in early spring before flowing - when most toxic and tasty to cattle

Front 36

What type of toxin is present in larkspur?

Back 36

Polycyclic diterpene alkaloids

Front 37

What is the mechanism of larkspur toxicity?

Back 37

Polycyclic diterpene alkaloids are neuromuscular blocking agents
-Competes w/ acetylcholine at receptors
-Cholinergic and nicotinic receptors

Front 38

What is the toxic dose of larkspur?

Back 38

0.5-1.5% BW may be lethald
-0.7% BW in 1 our=lethal

Front 39

Is the toxin in larkspur most poisonous to sheep, cattle or horses?

Back 39

Cattle > sheep or horses

Front 40

What are 6 clinical signs of larkspur toxicity?

Back 40

1) Nervousness
2) Weak staggering gait, paresis
-kneel due to weakness
3) Salivation
4) Twitching, tremors
5) Excitement, convulsions
6) Bloat
-due to position or foam?

Front 41

How long does it take for sudden death to occur from larkspur toxicity?

Back 41

Die in 3-4 hours

Front 42

What are 5 differential diagnoses for larkspur toxicity?

Back 42

1) Other neurotoxic plants
2) Neurotoxic chemicals
-lead
-organic-phosphate
3) Parturient paresis, grass tetany
4) Cerebral abscess
5) Meningitis
-Rabies could be

Front 43

Is there a definitive test available for larkspur toxicity?

Back 43

No, have to identify plant being eaten or possibly identify it in the rumen

Front 44

Is there a specific postmortem lesion indicative of larkspur toxicity?

Back 44

No, they will have bloat or congestion (But not specific)

Front 45

What are 3 things involved with treatment of larkspur?

Back 45

1) Relieve bloat
2) Detoxify? activated charcoal, cathartics
3) Physostigmine
-old larkspur remedy

Front 46

What are 3 ways to control larkspur toxicity?

Back 46

1) Biological, sheep
2) Herbicides
3) Limit grazing until alkaloid <3 mg/g in leaf
-social consumption, induced aversion

Front 47

What type of a plant is locoweed, astragalus sp., oxytropis sp., and crazyweed?

Back 47

A perennial legume
-resembles sweet pea

Front 48

What are the characteristics of locoweed, astragalus sp., oxytropis sp., and crazyweed?

Back 48

Numerous leaves on 2 sides each stem
-Flowers clustered on stalk, 1/2 in long
seed pod 1/2-1''

Front 49

Where is locoweed, astragalus sp., oxytropis sp., and crazyweed located?

Back 49

SW Texas
-Not Willamette Valley

Front 50

What are the signs of locoweed, astragalus sp., oxytropis sp., and crazyweed?

Back 50

Animal goes loco, crazy

Front 51

What is the scientific name of bracken fern?

Back 51

Pteridium aquilinum

Front 52

Where are bracken fern located? How are they spread?

Back 52

A true fern spread by rhizomes
-In wooded hilly areas

Front 53

What are the characteristics of the leaves of bracken fern?

Back 53

Leaves shaped like triangle
Bipinnately lobed leaves
Brown spores at edge

Front 54

What bracken fern is more palatable?

Back 54

young "fiddleneck"

Front 55

What is the toxin in bracken fern that poisons horses?

Back 55

Thiaminase in horses

Front 56

What is the toxin in bracken fern that affects cattle? What does the toxin do?

Back 56

Ptaquiloside- a bone marrow depressant

Front 57

True or false. Bracken fern toxicity is cumulative.

Back 57

True

Front 58

How much bracken fern does it take to kill a horse?

Back 58

6 lbs/ day for a month
3-5% of diet for 30 days
-Toxic in hay

Front 59

What are 2 compounds that contain thiaminase?

Back 59

1) Bracken fern
2) Equisetum

Front 60

Thiaminase destroys what vitamin? What is the net effect?

Back 60

Vitamin B1 (thiamin)
Central nervous system

Front 61

What is the function of thiamin in the body?

Back 61

needed for energy metabolism
-Pyruvate to acetyl CoA
-Oxidation of alpha ketoglutarate in citric acid cycle

Front 62

What are the 6 clinical signs of bracken fern toxicity in horses?

Back 62

1) Chronic ataxia
2) Weakness
3) Blind staggers ("fern staggers")
4) Twitching
5) Weight loss
6) Head pressing

Front 63

What are the nine differential diagnoses for bracken fern toxicity?

Back 63

1) Other thiaminase containing plants
2) Cervical vertebral malformation
3) EPM
4) Neurological herpes
5) Cerebellar disease
6) Equine degenerate myeloencephalopathy
7) Lower motor neuron disease
8) Polysaccharide storage disease
9) West Nile virus

Front 64

What are 3 ways to diagnose bracken fern?

Back 64

1) Consuming fern over period of time
2) Blood thiamine levels
-Normal 8-10 mcg/dL
-Affected 2-3 mcg/dL
3) blood pyruvic acid levels increased
Normal 2-3 mcg/dL

Front 65

What is the treatment for bracken fern toxicity?

Back 65

Thiamine 5mg/kg, IV
Repeat twice daily

Front 66

How can humans eat bracken fern?

Back 66

Some nutrient value in young shoots
-Boil to reduce toxin
-Eaten in Asia
-Like asparagus
-Could eat if lost in forest
-Carcinogenic if eaten over time

Front 67

What are 7 plants that cause convulsion or sudden death?

Back 67

1) Conium maculatum
-Poison hemlock
2) Cicuta maculata
-Water hemlock
3) Delphinium sp.
-Larkspur
4) Asclepias
-Milkweed
5) Astragalas sp.
-Locoweed
6) Lupinus
-Lupine
7) Cyanide producing & nitrate concentrating

Front 68

What is the scientific name of poison hemlock?

Back 68

Conium maculatum

Front 69

What are the characteristics of poison hemlock stems and leaves?

Back 69

Hollow stem
Purple spots
Parsnip-like root
Parsley-like leaves
Tall plant=10'

Front 70

What are the characteristics of the poison hemlock flowers?

Back 70

White flower
-Umbel, compound, 5 petal
-Like Queen Anne's lace

Front 71

True or false. Poison hemlock is palatable.

Back 71

False
*Human poisoning

Front 72

What is the toxic dose of poison hemlock?

Back 72

Very toxic, walnut size piece of root will kill a cow
-May need more of mature plant

Front 73

What is the mechanism of action of poison hemlock?

Back 73

Nicotinic effects
-stimulation followed by ANS paralysis

Front 74

What kind of toxin is in poison hemlock?

Back 74

Alkaloids
-Coniine & g-coniceine

Front 75

What are the 6 clinical signs of poison hemlock?

Back 75

1) Nervous
2) Trembling
3) Convulsions
-less than water hemlock
4) Salivation
5) Bloating
6) Coma

Front 76

How long does it take for poison hemlock to cause death?

Back 76

Rapid course
-Sudden death-takes 3-4 hours

Front 77

What are the 5 primary differential diagnoses of poison hemlock?

Back 77

1) Other plants causing seizures
2) Cl hydrocarbons, organic PO4, Pb
3) Encephalitis
-But poison hemlock too acute
4) Meningitis
-but poison hemlock too acute
5) Cerebral abscess
-but poison hemlock too acute
~Also rabies & epilepsy

Front 78

How do you diagnose poison hemlock?

Back 78

Detect alkaloid in stomach
Observe ingesting poison hemlock

Front 79

What is the treatment for poison hemlock?

Back 79

Unlikely anything practical will change outcome
-Evacuate stomach
-Respiratory support

Front 80

What are 2 ways to prevent poison hemlock toxicity?

Back 80

Don't eat it
Keep out of silage & hay

Front 81

What is the scientific name for water hemlock?

Back 81

Cicuta maculata

Front 82

Where is water hemlock located?

Back 82

In wet meadows and near streams

Front 83

What are the characteristics of the leaves of water hemlock?

Back 83

Divided leaf w/ veins leading to notch

Front 84

What do the flowers of water hemlock look like?

Back 84

White umbrella-like flower

Front 85

Describe the root of water hemlock.

Back 85

Thick w/ hollow chambers

Front 86

What is the toxic dose of water hemlock?

Back 86

VERY TOXIC ESPECIALLY ROOT
8 oz may kill a cow or 0.2% of BW

Front 87

What is the toxin in water hemlock?

Back 87

Cicutoxin- a resinoid or unsaturated alcohol

Front 88

What happens within 15 minutes of ingesting water hemlock?

Back 88

Seizures