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