Management and Control of Ectoparasites Flashcards
How do organophosphates work and what is an example?
Bind to acetyl cholinesterase causing build up of neurotransmitter and paralysis
Diazinon
What is the risk of organophosphates?
Lipid soluble with high toxicity to humans (novichock)
Still licensed in sheep dips
What is the mode of action of synthetic pyrethroids?
excites cell membranes causing depolarisation and therefore paralysis
How can SPs be enhanced?
PBO- Piperonyl Butoxidc
How can SPs be administered?
Pour ons, spot ons, collars, absorbed on skin and diffuses through coat
What are two examples of SPs?
Permethrin, Cypermethrin
What are the two types of macrocyclic lactones and name examples of each?
Avermectins- ivermectin, doramectin, selamectin
Milbemycins- moxidectin
What is the mode of action of macrocyclic lactones?
Stimulate release of GABA from parasite nerve endings, more binds to receptors causing increased flow of chloride ions- cell hyper-polarisation- paralysis
Why do MLs not affect mammals?
GABA limited to CNS and MLs don’t cross the brain barrier
How can MLs be administered?
Injectables, orally, pour-ons, spot-ons
1) What breed of dog are sensitive to ivermectin?
2) How do MLs need to be administered for sheep scab?
1) Collies
2) Need an injectable- orals don’t work
What is the mode of action of Imidacloprid?
Binds to nicotinic ACH receptors in insects CNS- paralysis and death
What is the main use of imidacloprid?
Flea adulticide
What is the mode of action of Fipronil?
Blocks GABA receptors in fleas and ticks
1) Why does fipronil have a long lasting effect
2) What is fipronil toxic to?
3) What is fipronil used for?
1) Diffuses into sebaceous glands of hair follicles- reservoir
2) Toxic to fish and bees
3) Companion animals (fleas and ticks)
