Ectoparasiticides

Question 1

Why should ectoparasites be controlled?

Answer 1

Pet health (welfare, damage)
Owner health (dermatitis, bites, zoonoses)

Question 2

What are 3 broad ways to control ectoparasites?

Answer 2

Broad spectrum ectoparasiticides
Integrated pest mangement (IPM)
Non-chemical use

Question 3

How can broad spectrum ectoparasiticides be administered?

Answer 3

Parenteral - SC/IM
Oral
Topical - pour on, spot on, tags, collars

Question 4

What is done for integrated pest management (IPM)?

Answer 4

Hygiene and management of breeding sites
Vacuuming/washing bedding
Removing ticks
Dagging/crutching (remove dirty wool from around anus)

Question 5

What are examples of non-chemical use for ectoparasite control?

Answer 5

Protection of teats
Rugs (stripes)
Sticky tapes
Pheromones 
Sugar baits

Question 6

What are the 6 main classes of broad spectrum ectoparasiticides?

Answer 6

Organochlorides
Organophosphates
Synthetic pyrethroids
Macrocyclic lactones
Insect growth regulators
Isoxazolines

Question 7

Which class of ectoparsiticide is now banned and why?

Answer 7

Organochlorides

Enivornmental impact

Question 8

How do organophosphates work? What are they only used for now?

Answer 8

Bind to acetylcholinesterase
Build up of ACh = paralysis
Sheep dip

Question 9

What is a disadvantage of organophosphates? Give an example of an OP

Answer 9

High toxicity to humans

Diazinon

Question 10

How do synthetic pyrethroids work?

Answer 10

Excite cell membranes

Causes depolarisation and paralysis

Question 11

What are the advantages of SPs?

Answer 11

Rapid kill - not residual

Low mammalian toxicity

Question 12

How are SPs administered? Give 2 examples

Answer 12

Topical - skin

Permethrin, cypermethrin

Question 13

Which SP should not be given to cats and why

Answer 13

Permethrin = toxic to cats

Question 14

Macrocyclic lactones are used for both eco and exoparsites. What are the 2 groups and give an advantage of each. What breed is sensitive to one of these?

Answer 14

Avermectin - e.g. ivermectin (collies sensitive)

Milbemycin - e.g. moxidectin

Question 15

How do MLs work? Why is this safe in animals?

Answer 15

Stimulate release of GABA
Hyperpolarisation and paralysis
GABA transmission confined to CNS and drug cannot cross BBB - safe to animal

Question 16

How can MLs be administered?

Answer 16

Injection
Oral
Topical

Question 17

Are MLs local acting or systemic?

Answer 17

Systemic - lipophilic so stored in fat, slow release

Question 18

What is a disadvantage of MLs?

Answer 18

Long half life = residues in meat and milk

Question 19

What are the 2 types of insect growth regulators? Give an example of each

Answer 19

Chitin inhibitors - cyromazine

Juvenile hormone analogues (keep immature) - methoprene

Question 20

Isoxazolines are the newest class of drug. Are they local or systemic? are they absorbed fast or slow?

Answer 20

Systemic

Rapid absorption

Question 21

How do isoxazolines work?

Answer 21

Act on GABA/glutamate receptors

Question 22

What are the advantages of isoxazolines?

Answer 22

Fast acting

Lasts 1 month

Question 23

Give an example of 2 isoxazolines?

Answer 23

Afoxolaner

Fluralaner

Question 24

What are 3 other ectoparsitides that aren’t in the broad spectrum categories?

Answer 24

Imidacloprid
Fipronil
Amitraz

Question 25

How does imidacloprid work?

Answer 25

Binds to ACh receptors

Causes paralysis and death

Question 26

In what animals is imidacloprid used? What is it effective against?

Answer 26

Companion animals

Flea adulticide - NOT ticks

Question 27

How does fibronil work? What is an advantage of fipronil? What animals find fipronil toxic?

Answer 27

Block GABA transmitter
Highly lipophilic - long residual activity
Bees, fish

Question 28

What is amitraz used for? Which species can it not be used in?

Answer 28

Ticks - cattle dogs

Not horses and cats as contraindications