Parasitology Flashcards
cattle, SR, and equine
Which anthelmintic is resistance least common in for equine cyathostomins?
macrocyclic lactones
what is targeted selective treatment?
it is where you treat ONLY the animals that need to be treated as opposed to treated all of the animals.
Its based on the 70/30 rule (70% animals have 30% of the parasite pop. and only 30% animals have 70% of the parasite pop)
what anthelmintic kills hypobiotic larvae of small strongyles?
moxidectin
Are the targeted selective treatment protocols the same for equine, bovine, ovine, etc.?
no
what happens when cyathostomins are killed by anthelmintic drugs?
hypobiotic larvae repopulate the intestine
what do the major strongylid parsites of ruminants and horses have in common?
- eggs exit host in manure
- eggs dev infective stage in env
- anthelmintic resistance is a problem
- arrested dev in life cycle
what is fecal egg count used for in food animals? (2)
- breeding purposes
- ID high contaminators
What increases refugia in food animals?
targeted selected treatment
selective nontreatment
which 4 things can be used as indicators for targeted selective treatment in food animals?
- FEC
- Milk production
- FAMACHA
- BCS
what can speed development of anthelmintic resistance? (3 things)
- pour on products
- alternating anthelmintics
- long-action products
What is the impact/effects trichostrongyles have on immature cattle (<2y)?
clinical disease or subclinical impact on growth and development
What is the impact/effects trichostrongyles have on mature cattle (>2y)?
clinical disease is very UNusual.
Why are pour ons and long-acting products so popular?
because they are convenient and easier, and the pour ons are even really cheap.
What are the 3 drug groups for treating food animal parasites?
- macrocyclic lactones (-mectins)
- benzimidazoles (-bendazoles)
- nicotinics (-antel, -misole)
What is the deworming recommendation for COWS?
no routine recommendation – treat depending on circumstances (poor BCS, hx of chronic problems, etc.)
What is the deworming recommendation for spring-born calves?
some treat calves at the beginning of grazing season (march/april)
however MIDSUMMER treatment shows best benefit
+/- treatment at weaning (if you are keeping)
why do calves less than 4 months of age not have a high number of worms?
they arent grazing as readily
What is the deworming recommendation for fall-born calves?
deworm at pasture turnout/start of grazing season in order to limit maturation of larvae that are remaining from the previous season
only retreat them in the fall if they are staying for the next season
What are 3 other situations in which routine deworming treatments are common for food animals?
- animals entering feedlot
- backgrounding
- bringing in cattle from multiple sources
What is selective nontreatment?
not treating some animals to leave a certain percentage of the herd “untreated” to increase refugia and decrease the speed of resistance
Ex. you have a herd of 500 animals, so you should treat 400 and leave 10-20% untreated (100 animals).
why is targeted selective treatment not common in cattle?
it is not feasible to do FEC for a high number of cattle and not accurate since most eggs are from cooperia
and weights do not accurately predict the animals response to the deworming
What is the benefit of combining multiple anthelmintics to treat food animal parasites?
additive effect of treatment (kill more, broad spectrum)
when you achieve higher efficacy, there will be fewer resistant survivors (diluting resistant genes)