Parasites Flashcards
Is anthelmintic resistance a problem in cattle?
yes, but as of right now, we are unsure of the extent. We know that it is not the same level of an issue as it is in small ruminants.
Resistance is reported in all 3 drug groups (MLs, BZs, and nicotonics) but there just are not many people collecting data.
What (7) parasites are problematic in immature cattle?
- cryptosporidium
- coccidia
- lice
- trichostrongyles
- face fly, horn fly
- other biting flies and possibly ticks?
- theileria - emerging
what (6) parasites are problematic in cows?
- face flies, horn flies
- other biting flies and ticks?
- lice
- trichostrongyles
- theileria
- chorioptes
what (6) parasites are problematic in bulls?
- face flies, horn flies
- other biting flies
- lice
- trichostrongyles
- tritrichomonas
- chorioptes
What is the common complaint / signalment in cattle that are suffering from high parasite burdens?
poor-doing weaned calves/stockers/heifers
Adult trichostrongyles live in the _____________.
GI tract
eggs are passed in manure, then the larvae develop to L3 in 5-7d (depending on temperature and moisture levels). Adults will begin egg-laying in 3 weeks.
which trichostrongyles are important in cattle?
- ostertagia
- cooperia
there are others that contribute to gastroenteritis but they are rarely the primary pathogen present.
T/F: cooperia spp. are found in the small intestine of cattle and are highly pathogenic.
false – they are generally not highly pathogenic.
T/F: most strongylid eggs in the manure of young cattle are ostertagia
false – they are cooperia
this is why we dont use fecal egg counts in cattle
Which parasite requires much higher levels of macrocyclic lactones than ostertagia do?
cooperia spp.
Why are trichostrongyles of GREATEST importance in young cattle (1st and 2nd calf cows)?
because immunity develops over several years.
Subclinical infections characterized by decreased weight gain and growth are common.
When clinically affected, they experience diarrhea, weight loss, unthriftiness, and hypoproteinemia (bottle jaw)
what 3 drug groups are used the most?
- macrocyclic lactones (ivermectin, doramectin, eprinomectin, and moxidectin)
- benzimidazoles (fenbendazole, albendazole, oxfendazole)
- nicotinics (levamisole, morantel)
why is anthelmintic resistance different for cow-calf operations versus feedlot operations?
because resistance depends on production type and how they manage refugia.
In a feedlot situation, they are not on pasture/not grazing and they just get sent to slaughter, so selection for AR is low. Whereas in a cow-calf operation, these animals are having higher selection for AR and managing refugia is very difficult.
why is resistance to macrocyclic lactones are widespread problem?
- heavily used
- pour on convenience
- cheap
how do we test for anthelmintic resistance in cattle?
fecal egg count reduction test
- take fecal egg counts on animals AT time of treatment
- wait the amount of time for each drug to take effect (ML = 14-21d, BZD = 10-14d)
- repeat FEC
- calculate the reduction in FEC
interpretation: 95% reduction = full efficacy; 90-95% = possible resistance; 80-90% = resistance is likely; 80% or lower = resistance highly likely