Nervous and Respiratory System Toxicity

Question 1

Fumonisin

Answer 1

Mycotoxin infecting corn kernel
Causes Equine leukoencephalomalacia
Degeneration of white matter
States with warm humid climates

Question 2

Toxins associated with fumonisin

Answer 2

Fumonisin B1 and B2 stored in moldy corn, commercial and pelleted feeds

Question 3

CS of fumonisin toxicity

Answer 3

Neurotoxic (first) and hepatotoxic
Compulsive walking, hypersensitivity, head pressing, muscle tremors and death

Question 4

T/F: death within 4-24 hr after onset of CS with fumonisin toxicity

Answer 4

TRUE

Question 5

Dx fumonisin

Answer 5

Feed analysis (fumonisin levels)
Clin path: ↑ liver enzymes, BR, and CSF protein

Question 6

How does fumonisin look on necropsy?

Answer 6

Liquefactive necrosis and malacia of white matter

Question 7

Pathophysiology of fumonisin toxicity

Answer 7

Disrupts endothelial cell walls and BM → vasc damage in brain → degeneration

Question 8

Tx of fumonisin toxicity

Answer 8

Tx cerebral inflamm and edema
Corticos, NSAIDs and DMSO
Diuretics and mannitol (if not internal bleeding/ anemia)
Thiamine (B1)
Human euthanasia

Question 9

Botulism

Answer 9

Decaying organic material (C. botulism)
Types A, B and C1* toxin
Normal mentation

Question 10

CS of botulism

Answer 10

Progressive flaccid paralysis
Inability to eat/ swallow, ptyalism, nasal discharge, muscle tremors, difficulty rising, dyspnea and death

Question 11

What causes botulism

Answer 11

Ingestion (moldy feed/ hay) or exposed wounds
Hay baled wet or stored in damp warm environment

Question 12

Botulism toxin

Answer 12

B*, C and D from Clostridium botulism
Forage poising (adults) and shaker foal syndrome

Question 13

Forage poisoning

Answer 13

Ingestion
Dyspnea, flaccid tail and muscle tremors
Severe paresis to rapid recumbency
Unable to retract tongue, drooling

Question 14

Shaker foal

Answer 14

Toxicoinfectious botulism (type B and C)
1-12m old (early as 2 weeks)
Ingests soil with C. botulism

Question 15

CS of Shaker Foal

Answer 15

Inability to swallow (drooling, nasal discharge while nursing, repeated cough)
Poor tone, abnorm gait, progressive weakness and CS then death

Question 16

Tx of botulism

Answer 16

Fatal if not given antitoxin: botulism antitoxin and hyperimmune plasma
Supportive therapy

Question 17

Prevention of botulism

Answer 17

Vaccinate adults with endemic (type B toxoid)

Question 18

Nigropallidal encephalomalacia

Answer 18

Yellow star thistle and Russion Knapweed
Toxin: sesquiterpene lactone (parkinsonism, chewing dz and wooden expression)

Question 19

How does a horse get Nigropallidal encephalomalacia

Answer 19

Eating large quantities of YST and RK
Green and dried plants toxic
neuro signs irreversible

Question 20

CS of yellow star thistle and Russian knapweed

Answer 20

Involuntary chewing, muscle tremors
Difficulty prehending/ swallowing, grinning appearance, protruding and lolling tongue

Question 21

Dx Russian knapweed

Answer 21

Repens causes lesion in the globus pallidus and sustantia nigra

Question 22

Bracken fern

Answer 22

Inadequate forage, incorporation into hay
Causes equine bracken staggers
Thiaminase inhibitor

Question 23

CS of bracken fern

Answer 23

Appear 30-60d after ingestion
Staggers, death, wide-base stance, arched back, m. tremors, progressive incoordination

Question 24

Bracken fern MOA

Answer 24

Thiaminase → deactivated B1 → accumulation of pyruvate/lactate → thiamine deficiency

Question 25

Tx of bracken fern

Answer 25

Untxable, administer thiamine initially

Question 26

Avermectins

Answer 26

Acute progressive neurologic condition
Progressive, ataxia, drooping lips, muscle fasciculations, bilat mydriasis, neg menace response

Question 27

Moxidectin

Answer 27

Macrocyclic lactone
Asc. paralysis, dyspnea, depression, tremors, ataxia, weakness and seizures

Question 28

Swainsonine (loco weed) initial CS

Answer 28

Depression and incoordination
Then aberrant behavior, aggression, circling, WL and death

Question 29

Swainsonine (loco weed) chr. CS

Answer 29

Created lysosomal dz
Alpha mannosidase inhibited
Swelling of axonal hillocks and growth of new dendrites and synapses (severe and irreversible)

Question 30

Tobacco

Answer 30

Toxin: nicotine
Hyperexcitability then depression, incoordination, paralysis, colic and death possible

Question 31

Marijuana

Answer 31

Toxin: delta-9 THC
Prolonged depression, incoordination, sleepiness/ excitation, hypersalivation, low BP, dilated pupils, seizure, etc

Question 32

Eucalyptus acute CS

Answer 32

Salivation, resp. irritant, diarrhea, depression and weakness

Question 33

Eucalyptus chr. CS

Answer 33

WL, lung damage (irreversible)
Chr. resp problems and death

Question 34

Cyanogenic plants

Answer 34

Early growth and plant damage: most toxic
Sudan, sorghum and hyrid
Death usually 30-45 minutes during severe convulsion

Question 35

CS of cyanogenic plants

Answer 35

Excitation with rapid breathing and HR
Drooling/ watery eyes, muscle spams
MM bright red then blue

Question 36

Dx cyanogenic plant toxicity

Answer 36

Hydrocyanic acid (GI, blood, liver and muscle)
Confirm with necropsy within 4 hr

Question 37

Tx cyanogenic plants

Answer 37

Tx immediately and oxygen therapy
Antidote: sodium nitrate, sodium thiosulfate and methylene blue

Question 38

Sudan grass

Answer 38

Requires 1 week to 6m of ingestion
Loss of nerve function to hind legs and bladder, stumbling when forced to move, paralysis, fetal deformities or fetal death

Question 39

Lemon grass

Answer 39

Oil grass, cyanogenic glycosides
Difficulty breathing, weakness, rarely death

Question 40

Black cherry

Answer 40

With family Rosaceae: apricot, plum, peach
Brick red mm, dilated pupils, difficult breathing and shock
Cyanide reduces O2 carrying capacity of Hg in RBCs