Organic Synthetic Herbicides

Question 1

What are the sources of Phenoxy derivatives of fatty acids (2,4-D)?

Answer 1

• accidental ingestion

- grazing freshly sprayed pastures/lawns

Question 2

What are the properties of Phenoxy derivatives of fatty acids (2,4-D)?

Answer 2

• Alters metabolism of plants -> incr accumulation of nitrate or cyanide
• palatable
• not stable in environment
• not degraded by rumen microflora and do not alter rumen microflora
• irritant to GI mucosa

Question 3

Which animals are most susceptible to Phenoxy derivatives of fatty acids (2,4-D)? Which are more sensitive?

Answer 3

Susceptible: Cattle and Dogs
Sensitive: Dogs

Question 4

What is the Acute LD50 of Phenoxy derivatives of fatty acids (2,4-D) in dogs?

Answer 4

~100mg/kg

Question 5

How are Phenoxy derivatives of fatty acids (2,4-D) absorbed?

Answer 5

Readily absorbed from the GI tract or by inhalation.

- poorly absorbed through the skin

Question 6

Where are Phenoxy derivatives of fatty acids (2,4-D) distributed in the body?

Answer 6

All over, including the liver, brain and kidney

Question 7

How long are the half lives of Phenoxy derivatives of fatty acids (2,4-D)?

Answer 7

usually short (few hours) but longer in dogs (up to 3-4 days)

Question 8

How are Phenoxy derivatives of fatty acids (2,4-D) metabolized and excreted?

Answer 8

metabolized mainly by hydrolysis and excreted mainly unchanged in urine by tubular secretion
- alkalinization of urine enhances renal excretion

Question 9

What is the mechanism of action of Phenoxy derivatives of fatty acids (2,4-D)?

Answer 9

• irritation of GI mucosa
• Affects skeletal muscle membranes in dogs
• uncouples oxidative phosphorylation, depresses ribonuclease synthesis

Question 10

What are the clinical signs of Phenoxy derivatives of fatty acids (2,4-D) in ruminants?

Answer 10

• Mainly GI and NM
• Ruminants: anorexia, rumen atony, may have bloat + diarrhea + ulcers in buccal mucosa. depression, muscle weakness + emaciation with no convulsions

Question 11

What are the clinical signs of Phenoxy derivatives of fatty acids (2,4-D) in dogs?

Answer 11

• anorexia, vomiting and bloody diarrhea
• myotonia and weakness of muscles (esp posterior muscles) and ataxia w/ rigidity of skeletal muscles
• at high doses onset is rapid (<1hr) = opisthotonos may occur and posterior paralysis in addition to severe GI signs

Question 12

What are the clinical signs of Phenoxy derivatives of fatty acids (2,4-D) in pigs?

Answer 12

Vomiting, diarrhea, muscle weakness and depression

Question 13

What lesions are associated with Phenoxy derivatives of fatty acids (2,4-D)?

Answer 13

no specific ones. Mainly GI dmg and degeneration of liver and kidney.
- Rumen stasis w/ ingested food is characyeristic finding.

Question 14

What specimens are best when conducting a lab diagnosis for Phenoxy derivatives of fatty acids (2,4-D)?

Answer 14

suspected forage, water, kidney, urine, liver, stomach contents

Question 15

What lab results might indicate Phenoxy derivatives of fatty acids (2,4-D) poisoning?

Answer 15

Elevated alkaline phosphatase (AP), lactate dehydrogenase (LDH), and creatinine phosphokinase (CPK) levels

Question 16

How are Phenoxy derivatives of fatty acids (2,4-D) diagnosed?

Answer 16

history of ingestion is important

• chemical analysis may help
• rule out other diseases

Question 17

How is poisoning with Phenoxy derivatives of fatty acids (2,4-D) treated?

Answer 17

• detoxification: wash skin w/ soap + water, activated charcoal
• Supportive and symptomatic treatment: IV fluids, antidiarrheals, rumenatorics