Pyrethrins And Pyrethroids

Question 1

What is a pyrethrin?

Answer 1

Active ingredient is an extract form the daisy-like flower, has been used as an insecticide since about 1000 BC- advertised as natural or botanical insecticide

Question 2

What are some of the uses of pyrethrins?

Answer 2

Home and farm insecticide
Farm animals
Companion animals- flea and tick control
*many cannot be used on cats so check labels

Question 3

What are some of the properties and toxicity?

Answer 3

Lipid soluble
Absorption is oral, dermal or inhalation
Same MOA as synthetic pyrethroids

Chronic toxicity through respiration, less dermal
Dangerous to children and young animals

HIGH TOXICITY to BEES (application at night, liquid rather than dust)
HIGH ACUTE TOXICITY TO FISH and AQUATIC INVERTEBRATES
HIGH ACUTE TOXICITY TO CATS

Question 4

What are pyrethroids?

Answer 4

Synthetic analogs of pyrethrins

BOP

Question 5

What are synergized pyrethrums?

Answer 5

Pyrethroids commonly formulated with a synthetic non-pesticide chemical (piperonyl butoxide, MGK-264)- a synergistic effect that increases the efficacy (lethality)

Pyrethroids now make up the majority of commercial household insecticides (3500 profits registered with EPA)

Question 6

Which one is the natural and which one is the synthetic compound? (Pyrethrins, Pyrethroids)

Answer 6

Natural- pyrethrins

Synthetic- pyrethroids

Question 7

What are the animals that pyrethrins and pyrethroids are most and least toxic to?

Answer 7

This is a neuro toxin

Low toxicity- Mammals

VERY TOXIC to fish- poor metabolism

A treated dog that swims in a pond can serve as a source of exposure

Question 8

What are the ranges of permethrin of topical products for dogs? Which species is more sensitive?

Answer 8

0.055-65% permethrin

Cats are more sensitive than dogs- reduced rate of metabolism (deficient in the enzyme GLUCURONIDASE)- leads to accumulation of metabolites

Question 9

What enzyme are cats deficient in?

Answer 9

GLUCURONIDASE TRANSFERASE

Question 10

Permethrin toxicity is one of the most common causes of poisoning in what species worldwide?

Answer 10

Cats

Question 11

What is the MOA?

Answer 11

Hyperexcitability of the nerve

Question 12

Do Type I or Type II (alpha-cyano group) have a greater effect on sodium channels?

Answer 12

Type II

• GABA receptor antagonist
• Inhibits neuronal Ca2+, Mg2+ ATPase activity- hyperexcitability

Question 13

What could be other MOAs of these?

Answer 13

Allergic rxns

Stimulate adrenal glands (glucocorticoids- increased cortisol) causing hyperglycemia

Question 14

What are some acute clinical signs?

Answer 14

Muscle tremors, depression, blindness (reversible), ataxia, lethargy, V+, D+, hyperexcitability, drooling, lip and tongue numbness etc.
-some dogs may show acute paralysis

Cats- many cases result in death 10-40% of poisoned cats die or need to be euthanized

Question 15

How do you diagnose this toxicosis?

Answer 15

Diagnosis is generally made based on history of exposure, appropriate CS+ and ruling out of other causes

Question 16

True or False. There is a specific antidote for pyrethrin/pyrethroid poisoning.

Answer 16

False.

Question 17

What can be used as a treatment for the symptoms?

Answer 17

Methocarbamol for severe muscle tremors

-DO NOT USE ACTIVATED CHARCOAL- rapid metabolism

Question 18

What is the prognosis?

Answer 18

Generally good for most animals, except the cat. Timing is essential