Small Ruminant Parasites Flashcards
What is the infective stage of haemonchus contortus?
L3
what are the 3 abomasal nematodes in SR?
- haemonchus contortus
- Teladorsagia spp.
- Trichostrongylus axei
T/F: Trichostrongylus axei is the only trichostrongyle of the abomasum
true
What are 4 small and large intestinal nematodes of importance in SR?
- Trichostrongylus spp.
- Cooperia spp.
- Oesophagostonum spp.
- Trichuris spp.
Which parasites cause parasitic gastroenteritis (PGE) in sheep and goats?
ALL parasites except haemonchus
they cause slow growth, weight loss, and reduced production of milk/wool/meat
why are sheep more at risk for getting internal parasites than goats?
behavior!
goats are browsers and sheep are grazers.
parasites cannot be any higher than 4 inches from the ground, so sheep are at higher risk due to grazing at this level.
Between sheep and goats, which is SLOWER to develop immunity to internal parasites?
goats.
T/F: the more parasites there are in an individual, the more likely this individual is to suffer negative consequences.
true
how do SR obtain GI parasites?
ingest the larvae while grazing
eggs are passed in manure and develop to L3 which gets ingested by the sheep/goat in the pasture
Describe the ‘negative binomial distribution’ of parasites within the SR population.
Most of the individuals have few/no parasites
Only few of the individuals have most/a lot of parasites
(70/30 rule) parasite populations in animals are aggregated.
What were some of the early recommendations that lead to selection of populations of nematodes that are RESISTANT to anthelmintics and decreased refugia?
- deworm ALL animals at same time
- deworm when fecal exams are +
- deworm regularly (q3-6m)
- rotate antiparasitic drugs
- place animals onto clean pasture after deworming
what is the goal of intergral parasite management (IPM)?
keep worms at a level that does NOT have detrimental health effects
this includes more factors than only anthelmintic tx.
what are the 3 basic principles of IPM?
- reduce exposure of hist to infective stages (grazing management)
- develop more favorable response to host GI parasite infection
- deworming
what things can you do to positively influence grazing management for IPM?
- limit pasture exposure
- dry the pasture and produce hay to kill larvae
- decrease stocking rate
- do not allow sheep to graze on pastures previously used by goats
- increase rest time of the pasture and rotate them.
When is immunity to GI parasites fully developed?
in mature animals
so first lactation animals are STILL vulnerbale.
Dry, non-pregnant ewes/does are most immune.