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RUSVM Toxicology > Organic Herbicides - Dipyridyls And Phenoxy Acids > Flashcards

Organic Herbicides - Dipyridyls And Phenoxy Acids Flashcards

1
Q

How do animals generally get Phenoxy acid toxicosis?

A

Spayed forages above recommended concentration

Accidental ingestion concentrates or sprays
Grazing on freshly sprayed pasture/ laws

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2
Q

Phenoxy acids alter the metabolism of plants which increases their toxicity by increasing accumulation of what compounds?

A

Nitrates or cyanide

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3
Q

T/F: Animals generally dont get phenoxy acid toxicity because plants sprayed with it are less palatable

A

False

—> can improve palatability of some poisonous plants

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4
Q

What species is most sensitive to phenoxy acid toxicity?

A

Dogs

Acute oral toxicity 100mg/kg (moderately toxic)

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5
Q

Where are phenoxy acids absorbed and distributed?

A

Absorbed in GI (poorly from skin)

Distributed all over the body incl the liver, kidney, and brain

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6
Q

The half life of phenoxy acids is ______ in cattle, but _______ in dogs

A

Hours; 3-4days

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7
Q

Phenoxy acids are weak acids, how can their excretion be enhanced?

A

Alkalinizaiton of urine (eg sodium bicarb)

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8
Q

What is the MOA of phenoxy acids?

A

Irritation of the GI mucosa
Affect skeletal membranes in dogs
Uncouple oxidative phosphorylation and depress ribonuclease synthesis

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9
Q

What are the clinical signs associated with phenoxy acids?

A

GI and neuromucuscular

Vomiting, diarrhea, ulcer on buccal mucosa, rumen atony and bloat (ruminant)
Depression and muscle weakness
Dog only- weakness of the posterior muscles and ataxia with rigidity of skeletal muscles

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10
Q

What are lesion that can be seen with phenoxy acid toxicosis?

A

Nonspecific

Mainly GI damage and degeneration of the liver and kidney
Rumen stasis with ingested food is characteristic

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11
Q

What is the best sample for lab diagnostics if you suspect phenoxy acid toxicity?

A 
Forage 
Water
Kidney
Urine
Liver
Stomach contents and feces
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12
Q

What biochem data would you see elevated in phenoxy acid toxicity?

A 
ALP
lactate dehydrogenase (LDH) 
Creatine phospholipase (CPK)
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13
Q

What is the treatment for phenoxy acid toxicity?

A

Detoxification

  • wash
  • activated charcoal

Supportive

  • IV fluids
  • antidiarrheals and rumenatories
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14
Q

Of the diphydril herbicides, what are the restricted use and general use herbicides

A

Restricted use - Paraquat

General use- Diquat

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15
Q

T/F: dipyridyl herbicides are rapidly inactivated by light and soil

A

True

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16
Q

Dipyridyl herbicides are stable in what conditions

A

Stable -Neutral and acid

Destroyed - Alkali

17
Q

What is the toxicity of dipyridyl herbicides?

A

25-75mg/kg in cats, dogs, pig, and sheep (highly-moderately toxic)

18
Q

Toxicity of Paraquat is enhanced by what?

A

Selenium-vitE deficiency
Depletion of tissue glutathione
Oxygen therapy

19
Q

T/F: diquat and Paraquat are poorly absorbed from the GI system

A

True

20
Q

Paraquat can be distributed all over the body but achieves high concentrations where?

A

Lung (x10)

21
Q

Where is Paraquat excreted?

A

Urine

Unchanged

22
Q

What is the MOA of Paraquat and diquat ?

A

Reduced by nicotinamide-adenine dinucleotide phosphate (NADPH) to produce singlet oxygen

Singlet oxygen reacts with lipid of cell membrane —> hydroperoxides

Free radicals—>cell membrane damage, cellular degeneration, and necrosis

23
Q

What are the early signs of Paraquat and diquat toxicity?

A

Vomiting, anorexia, and depression

Ataxia, dyspnea, and seizures

24
Q

What are the delayed signs of paraquat and diquat toxicity?

A

Respiratory signs include tachypnea, dyspnea, harsh respiratory sounds, cyanosis, and reduced pulmonary compliance

25
Q

The respiratory signs seen in subacute/chronic toxicity in dipyridyl toxicity are due to ???

A

Progressive pulmonary fibrosis

26
Q

What lesions are seen in dipyridyl toxicity?

A

Pulmonary congestion edema, congestion, hemorrhage, fibrosis, and failure of the lung to collapse

Lingual ulcers
Liver, kidney, and spleen may be congested and enlarged

27
Q

What are the specimens for chemical analysis in acute and chronic cases of dipyridyl toxicity?

A

Acute - plant material, stomach content, urine

Chronic - lung

28
Q

What are your DDX for things causing tachypnea, dyspnea, harsh respiratory sounds, cyanosis, and reduced pulmonary compliance?

A

Dipyridyl toxicity
Pneumonia
Inhalant toxicants - gases, vapors, and dusts

29
Q

How do you treat dipyridyl toxicity?

A

Detox

  • emetic
  • activated charcoal
  • Bentonite/fullers earth choice
  • saline cathartics following the adsorbent

Supportive

  • fluid therapy
  • hemodyalysis or peritoneal dialysis

Biochemical antagonists

  • orgotein
  • acetylcystine
  • ascorbic acid
  • niacin or riboflavin
30
Q

What type of supportive therapy is contraindicated in early dipyridyl toxcity and why?

A

Oxygen therapy

Can increase lung damage

RUSVM Toxicology (23 decks)

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