Parasiticides Flashcards
How does the dose of ivermectin for heartworm prevention differ from its use in other parasitic diseases and how does this impact use in the ivermectin-sensitive breeds?
The dose for heartworm is 6μg/kg po every month
The dose in other parasitic diseases in 0.2 mg/kg sc
The dose used in other parasitic disease may be toxic to sensitive dogs with ABCB1-1Δ gene defect
What is the effectiveness of febantel in dogs and cats?
Both dogs and cats, hooks, rounds, and whips
What is the effectiveness of fenbendazole in dogs and cats?
Roundworm, hookworm, whipworm, Taenia tapeworm
Extra label action against roundworm, hookworm
What is the effectiveness of macrocyclic lactones (ivermectin family) in dogs and cats?
Dogs (extra-label) and cats: hookworm
In dogs, it has variable efficacy against rounds and whips
What is the effectiveness of praziquantel in dogs and cats?
Tapeworms (Echinococcus granulosus)
What is the effectiveness of pyrantel pamoate in dogs and cats?
Roundworms and hookworms in dogs
Cats: extra label against rounds and hooks
What is the effectiveness of fenbendazole in horses?
Large and small strongyles, pinworm, ascarids (particularly effective)
What is the effectiveness of macrocyclic lactones (ivermectin family) in horses?
Effective against everything except tapeworms
Effective against benzimidazole resistant cyathostome
What is the effectiveness of piperazine in horses?
Ascarids, some activity against large and small stronglyes
What is the effectiveness of pyrantel pamoate in horses?
Large and small strongyles, ascarids, pinworms Also tapes (Anoplocephala perfoliata)
What is the effectiveness of macrocyclic lactones (ivermectin family) in cattle?
Oesophagostomum, Ostertagia, Haemonchus
What is the effectiveness of clorsulon in cattle?
Fasciola
What is the effectiveness of albendazole in cattle?
Oesophagostomum, Ostertagia, Haemonchus, Fasciola
What is the effectiveness of fenbendazole in cattle?
Oesophagostomum, Ostertagia, Haemonchus
What is the effectiveness of morantel in cattle?
Oesophagostomum, Ostertagia, Haemonchus
Why do benzimidazole anthelmintics like fenbendazole require three daily doses in dogs but only require one dose to be effective in ruminants and horses?
Dogs and cats do not produce the metabolite as well as horses and cattle, so it needs to be give multiple times to be effective
Which of the following is the safer form of pyrantel and why: pyrantel pamoate or pyrantel tartrate?
Pyrantel pamoate because the pamoate salt is poorly absorbed from the GI tract
How does natural pyrethrin differ from the synthetic pyrethroids in terms of duration and potency against ectoparasites that a susceptible to this group of agents?
Natural pyrethrin: quick knock down, but short duration
If you spray an insect with natural pyrethrin, it will be dying within seconds
Synthetic pyrethroids: 1st generation is identical to the natural pyrethrin
They have a much slower kill than the natural pyrethrin.
Apply to an animal and fleas are still running around a couple of hours later, but it still works
Why is piperonyl butoxide combined with natural pyrethrin insecticides?
Piperonyl butoxide is a synergist inhibiting detoxification enzymes in the insect
Permethrin is contraindicated in what species?
Cats and fish
What protocol does the American Heartworm Society recommend as the best way to treat dogs to remove adult heartworms?
AHWS recommends a 3 dose regimen of melarsomine. One dose, wait 30 days, then 2 doses 24 hours apart
Address why the “three dose protocol” (also called the “split protocol”) of melarsamine is now preferred over the original “two dose protocol”.
The two-dose protocol is only 90% effective and the 3 dose is 98% effective
Why are doxycycline and prednisolone used as part of the HW protocol?
Doxycycline (given before treatment) reduces the severity and the incidence of pulmonary embolism after adulticide therapy and it affects Wolbachia. Prednisolone is used to control the signs of pulmonary embolism after treatment with melarsomine
When is heartworm preventative begun prior to heartworm adulticide therapy and why?
ML is given 2 months before giving melarsomine to eliminate immature worms less than 60 days, allows worms older than 60 days to mature to an age that is susceptible to melarsomine, reduces or eliminates microfilariae levels, and stunts adult HW development
What is the hypothesis proposed for how a few heartworm variants in the Mississippi Delta are resistant to the macrocyclic lactone preventatives?
There are genetic differences at four SNPs in resistance isolates. The p-glycoprotein pump in the organisms is involved. It normally pumps out the ML a little, but it still kills the larval form. In the resistant strains, they think something has mutated the gene for the pump so there are a lot more pumps or they have the same number of pumps, but they are more efficient
What macrocyclic lactone product has shown effectiveness against the Mississippi Delta resistant strains of heartworms in a laboratory disease model?
Advantage multi (moxidectin) was 100% effective in both strains of worms
Anthelmintic resistance is now documented for ivermectin in which of equine internal parasite(s)?
Parascaris
Which of the anthelmintic(s) should not be used during early gestation in cattle, sheep, or goats due to embryo toxicity or teratogenicity?
Albendazole
Which small animal topical product used for internal parasite control has been shown to interfere with fetal development in lab animals and should not be handled by women who are pregnant or may become pregnant?
Emodepside
Which oral small animal anthelminthic is contraindicated in pregnant animals?
Pyrantel + Praziquantel + Febantel (Drontal plus)
Carbaryl (Sevin®) belongs to what family of insecticides? What is its antidote if overdosed into toxicity?
Carbamates, but these are no longer available for animal use
Atropine is used to treat an overdose
What is Afoxolaner (NexGard) effective against? Is is given topically or orally?
Fleas and ticks
Oral
What is Amitraz effective against? Is is given topically or orally?
Ticks
Topical
What is Carbaryl (Sevin) effective against? Is is given topically or orally?
Fleas and ticks
Topical
What is Dinotefuran (Vectra) effective against? Is is given topically or orally?
Fleas
Topical
What is Fipronil (Frontline) effective against? Is is given topically or orally?
Fleas and ticks
Topical
What is Fluralaner (Bravecto) effective against? Is is given topically or orally?
Fleas and ticks
Oral in dogs, topical in cats
What is Imidacloprid (Advantage) effective against? Is is given topically or orally?
Fleas
Topical
What is Indoxacarb (Activyl) effective against? Is is given topically or orally?
Fleas
Topical
What is Nitenpyram (Capstar) effective against? Is is given topically or orally?
Fleas
Oral
What is Permethrin effective against? Is is given topically or orally?
Fleas and ticks, but more effective on ticks
Topical
What is Sarolaner (Simparica) effective against? Is is given topically or orally?
Fleas and ticks
Oral
What is Spinosad (Comfortis) effective against? Is is given topically or orally?
Fleas
Oral
How does the combined use of spinosad with deworming doses of ivermectin cause toxicity?
It is a p-glycoprotein pump inhibitor and can cause toxicity when given with drugs that are a substrate for the pump
How do lufenuron, methoprene, and pyriroxyfen differ from traditional insecticides in terms of how they affect the flea cycle?
Lufenuron: chitin synthesis inhibitor
Methoprene, pyriproxyfen: juvenile hormone mimic
Juvenile hormone must be absent for a pupa to molt into adult; breaks the life cycle of the insect
Pyriproxyfen is more stable because methoprene degrades when exposed to UV light
What side-effect is most commonly seen with amitraz dip and what can be used to reverse it?
Can cause sedation in some dogs
Reversible with alpha-2 antagonist
What enzyme system is inhibited by amitraz thereby predisposing to adverse drug interactions?
MAO (monoamine oxidase) inhibitor
What ectoparasites are the macrocyclic lactones (ivermectin family) effective against?
Sarcoptic mange
Otodectes (ear mites; when given both systemically and topically)
Demodectic mange (extra-label daily use)
What is effective against demodectic mange?
Extra label use of macrocyclic lactones (ivermectin family)
Amitraz topically Afoxolaner
Fluralaner
Sarolaner
What is uinique above selamectin (Revolution) as a macrocyclic lactone?
Its effective against fleas
Tetrachlorvinphos (Equitrol®), diflubenzuron (Equitrol II®). and cyromazine (Solitude IGR®) are all “feed-through” fly control products. What does the term “feed-through” imply in terms of what life stage the act upon to help control flies? How does the percentage of animals receiving these products on a farm affect their usefulness?
Added as a top dressing to the grain of the horse and enters into the manure and in the manure it prevents the life cycle of the fly from completing when they legs in the manure
Ever horse in the stable needs to be on this. If it is just one and there are 10 others, you will not get fly control
Fenbendazole (Panacur®) may be superior to ivermectin when controlling what helminth in foals?
Ascardis
Moxidectin (Quest®) may be more effective than ivermectin when controlling what helminth in adult horses?
Small strongyles
Name two agents approved to treat liver flukes in cattle.
Clorsulon and albendazole
Albendazole should not be used in what subgroup of cattle and why?
Do not give to lactating dairy cattle
They are lipid soluble and enter the milk very well
Which older anthelminthic when injected in cattle causes occasional cholinergic toxicity (salivation, head shaking, ataxia, muscle tremors)?
Levamisole
Which agents are effective against tapeworms, including Dipylidium, in dogs and cats?
Praziquantel and episprantel
What is the deficiency in activity of epsiprantel versus praziquantel?
Esiprantel is not approved for Echinococcus granulosus whereas praziquantel is extremely effective against it
What tapeworm species is fenbendazole only effective against?
Taenia Tapeworm
What categories of insecticides are used in ear tags for fly control in cattle?
Macrocyclic lactones (Doramectin, Eprinomectin, Ivermectin, Moxidectin)
Synthetic pyrethroids
Organophosphates
Fenbendazole is effective against what GI protozoal infection?
Giardia
How is febantel related to fenbendazole? How does it differ relative to effectiveness against whipworms?
It is a prodrug of fenbendazole, which is subsequently further metabolized to active metabolites
It claims to have single-dose efficacy against whipworms
What role does albendazole have relative to echinococcus human infections?
Can treat the infection in the tissue phase, when there are large tissue cysts
Albendazole has been advocated in the past for use in dogs. What major toxicity limits its usefulness in this species?
Bone marrow suppression
What are the deficiencies in the spectrum for Heartgard (only ivermectin) in dogs?
No nematodes
What are the deficiencies in the spectrum for Heartgard (only ivermectin) in cats?
No roundworms
What are the deficiencies in the spectrum for Heartgard Plus (ivermectin and pyrantel pamoate) in dogs?
Does not get whipworms
What are the deficiencies in the spectrum for Revolution (selamectin) in dogs?
Limited activity against hooks and whips
What are the deficiencies in the spectrum for Proheart 6 (moxidectin 6-month sustained-release injection) in dogs?
Not effective against roundworms
