Ectoparasitic

Question 1

mechanism of neurotoxin ectoparasiticides

Answer 1

Most as this way- act on parasite CNS synapses, axons or neuromuscular junctions
-> spastic or flaccid paralysis
All adulticide; some ovicidal/ larvividal also
Insects and mammals have many neurotransmitters in common, better safety profiles if drugs act on non-mammalian mechanisms

Question 2

6 possible targets of neurotoxins

Answer 2

1. Nicotinic acetylcholine receptor stimulant (Neonicotinoid)
2. Cholinesterase Inhibitor (Organosphates)
3. GABA inhibitors (Phenylpyrrazole)
4. Cl channel stimulants (macrocyclic lactones) CANT COLLIEs
5. GANA +Cl channel inhibitors (Isoxazolines)
6. Na channel stimulants (Pyrethoids) NOT CATS

Question 3

Which class are nicotinic acetylcholine receptor stimulants use + 3 examples

Answer 3

neonicotinoids- LICENCED AGAINST FLEAS IN SMALL ANIMALS

Imidacloprid, Nitenpyram, Dinotefuran

Question 4

what is imidacloprid and use

Answer 4

neonicotinoid/ Nicotinic acetylcholine receptor stimulant

Licenced for fleas + chewing lice (dogs), fleas in rabbits
Topical absorption, not absorbed systemically- washes off concerns re. waterways

Question 5

What are organophosphates, example and uses

Answer 5

Cholinesterase inhibitors

Wide activity, use has reduced greatly due to neurotoxicity concerns

Diazinon (dimphylate)

Question 6

Diazionon (dimphylate)

Answer 6

Sheep dip
wide range of ectoparasites- sheep scab, blow fly larvae, lice, ticks, keds

Question 7

What are phenylpyrrasoles, action and example

Answer 7

GABA inhibitors
Active against fleas + ticks

Fipronil

Question 8

Fipronil uses, toxic to….

Answer 8

Frontline
Active against fleas, ticks, (+ chewing lice in dogs)
Available OTC
Topical Application
Not absorbed systemicall- concern re waterways

TOXIC TO RABBITS

Question 9

What are isoxazolines, uses and examples

Answer 9

GABA + chloride channel inhibitors

Liceced for fleas+ticks +other specifics

Rapid onset of action- available as tablets, spot-on or in-water (poultry)
Absorbed systemically- unaffected by bathing

CAUTION RE-USE IN SEIZURE PATIENTS

Examples: Flurlaner, Sarolaner, Alfoxolaner, Esafoxolaner, Lotilaner

Question 10

What is fluorolaner, how long is it effective for

Answer 10

Isoxazoline

Used for fleas + ticks (+ demodex/sarcoptes in dogs), (+ red mite poultry)
Effective for 3 months

Question 11

what is licenced for otodectes in dogs

Answer 11

Sarolaner
Isoxazolane, Gaba + CL channel inhibitor

Question 12

What is a macrocytic lactone, use and examples

Answer 12

Chloride channel stimulator

Many preparations available
Absorbed systemically- don’t wash off
Action vs ECTO (insects and arachnids) and ENDO parasites (esp. GI nematodes)

Avermectins (Ivermectin, Doramectin, Eprinomectin, Selamectin), Milbemycins (milbemycin oxime, Moxidectin)

Question 13

in what case can macrocytic lactones cause neurotoxicity

Answer 13

if MDR1 gene mutation esp. collies/herding breeds if not used according to data sheet

MDR1 mutation-> failure of p-glycoprotein pump -> drug crosses blood-brain barrier -> neurotoxicity -> death

Question 14

What is ivermectin

Answer 14

Avermectin, macrocytic lactone, chloride channel inhibitor
TOXIC TO CHENOLIANS
widely used in large animals, birds and many exotics
AVOID FOR DOGS/CATS

Question 15

What is a pyrethroid, uses and examples

Answer 15

Sodium channel stimulant
Adulticide vs fleas, flies, lice, keds, ticks (slower kill than isoxazolines), some mites

Also repellant, in large number of products
esp. farm/horses/birds and environmental flea-sprays
TOXIC TO CATS (except flumethrin)
TOXIC TO AQUATIC LIFE (not suitable for dogs that swim, care to protect fish tank from environment spray)

Permethrin, Cypermethrin, Deltamethrin, Flumethrin (collar)

Question 16

What are IGRS plus 3 examples

Answer 16

insect growth regulators
No adulticide properties
Effective in interrupting juvenile stages of the insect life cycle- but slow to act (e.g. 60-90 days for lufenuron)-> often used with adulticides e.g. in flea infestation

Juvenile hormone analogues (S-methoprene pyroxyfen Fenoxycarb), chitin synthesis inhibitors (lufenuron), triazine derivative (cyromazine dicyclanil)

Question 17

Juvenile Hormone analogues

Answer 17

S-methoprene Pyriproxyfen Fenoxycarb
Mimic activity of juvenile hormone so the development of egg/larva arrested
commonly in environmental spreys, collar and spot-ons

Question 18

Chitin synthesis inhibitors

Answer 18

Lufenuron

Prevent normal development of exoskeleton-> stop larvae developing

Question 19

triazine derivatives

Answer 19

Cryomazine dicyclanil

Disrupt cuticle turnover- moult inhibitors
Preferential efficacy for Dipiteran fly larvae-> prevention of cutaneous myiasis (sheep and rabbits)

Question 20

What are pyrethroids

Answer 20

Repellant
Commonly used for tick repellant action but slow time to kill, som licenced for sand fly repellent (leishmaniasis prevention)
cattle ear tags for fly repellant
repellant product for culicoides midges (horse)

Question 21

Example and action of synergists

Answer 21

Piperonyl butoxide

Inhibit detoxification pathways -> increase available concentration of insecticide
used especially with pyrethrins to reduce insecticide content

Question 22

Lime Sulfur Dip

Answer 22

Traditional pesticide
Also fungicidal and bacteriocidal
UNpleasnant odour, may stain light coats, must prevent ingestion

Question 23

Desiccants

Answer 23

sodium polyborate

used in environment e.g. carpet powders

Question 24

Mechanical agents

Answer 24

sharp particles reportedly damage parasite exoskeleton
Diatomaceous earth- used in environment e.g. carpet powders