Nematodes of Cattle Flashcards
what parasites affect the abomasum in cattle
Haemonchus
Ostertagia
Trichostrongylus axei
what are species that affect the small intestine of cattle
Cooperia
Trichostrongylus
Nematodirus
Bunostomum
Strongyloides
what are species that affect the large intestine of cattle
Chabertia
Trichuris
Esophagostomum
what are species that affect the lungs of cattle
dictyocaulus
what are species that affect the eye of cattle
thelazia
what are species that affec the connective tissue of cattle
Onchocerca
Parafilaria
Stephanofilaria
what are the most common nematodes of temperate regions
- cooperia oncophora
- ostertagia ostertagi
- dictyocaulus viviparus
what are abomasal lesions that ostertagia ostertagi cause
Gastric gland with hyperplastic change
Loss of cellular differentiation
Central orifice marking exit of worm
Resolution over ~2 months
what is the host response to ostertagia ostertagi
HCl secretion reduced: pH increases
gastrin is secreted
pepsinogen does not convert to pepsin
leads to
hypergastrinemia
pepsinogen increases
what role does gastrin play in appetite control
Parasite impact on appetite: gastrin increases —> negative feedback on appetite (decrease DMI)
what affect does PGE have on calves at pasture
decreased growth
what is inhibited larvae and ostertagiosis type II
Infective larvae acquired in late summer/autumn remain in an inhibited state as early 4th stages in the gastric glands
Inhibited larvae are >2mm long, metabolically inert and cause neither a pathophysiology nor an immune response
Inhibited larvae resume development in late winter (precise stimulus not known)
If large numbers of worms mature simultaneously, severe clinical disease can result
how long does it take for immunity to develop against cooperia
one full grazing season
how long does it take for immunity to develop against ostertagia ostertagi
two full grazing seasons
what are immune effects on parasite biology
Decrease in fecundity
Stunting of growth
Retardation and arrested development
Expulsion of adult worms
Limited number of incoming infective larvae establish
what are immune effects on host biology
Clinical disease
Pathology
Pathophysiology
Behaviour
Productivity
how do ostertagia and cooperia develop and disperse on pasture
n warm weather there can be rapid build up of infective larvae on pasture (22-23ºC)
Larvae can’t move around much (~5cm from shit), but rain can wash it up to ~1m
Dispersed by earthworms, flies, stock movements, footwear, harrowing
what is the longevity of PGE larvae on herbage
Majority of larvae disappear within 12 months
Some survive to 24 months
Soil may act as a reservoir
what is the seasonality of PGE in weaned dairy calves
Overwintered larvae
Calves turned out in April and will be picking up infective larvae and will start to pass out eggs in feces (PPP 21 days)
The more the eggs come out and the faster they develop (increased temp) the greater the amount of larvae on the pasture —> more rapid turnaround
Calves will be grazing more as they get older and bigger (DMI increases) —> more eggs being ingested
Quickly after initial exposure there can be decreased growth rate (decreased DMI)
If untreated and no moving of calves —> clinical disease in mid summer period (July onwards)
what is the seasonality of PGE in beef calves
Spring born calves graze with their mothers
As they are taking in a relatively small amount of DMI —> mostly milk
Continue to suckle right up until weaning
Over wintered larvae + cows contributing to the eggs on pasture
Calves won’t be taking in a large amount of DMI until second half of grazing season
Don’t reach the same amount of larvae ingested as dairy calves do and if they do it doesn’t happen until late summer and autumn
Calves don’t display clinical disease because they don’t ingest as much Ostertagia as mom does but they are exposed and can develop disease after weaning
At risk to type II ostertagia
what are PGE markers and monitoring strategies
what is the problem with using fecal egg counts as PGE markers and monitoring
Fecal egg count doesn’t correlate with # of parasites, ADG, pathology & performance of individual animal
Useful for overall group burden and how much pasture contamination there is
why is albumin useful in PGE marker and monitoring
Albumin is useful because it gives indication of protein loss in GI tract associated with Ostertagia lesion in abomasum
what is the first marker of decreased performance in PGE
decreased DLWG
how is PGE controlled through grazing management
- Limit exposure of cattle to infection
- Mitigate impact
- Reduce larval challenge:
- Newly sown grass fields
- Grass re-growth after silage/hay
- Mixed grazing
- Ostertagia is specific to cattle, can’t develop in sheep —> sheep will be hoovering up the eggs
what is high risk pastures for PGE
grazed by cattle <1 year old within last year
permanent pasture
what is medium risk pastures for PGE
permanent pastures grazed by cattle 1-2 years old within last year
silage/hay aftermath: grazed by cattle <1 year old the same year
what are low risk pastures
permanent pastures: grazed by adult cows, sheep or other species within last year
silage/hay aftermath: grazed by cattle the prev year
newly sown leys: grazed by cattle the prev year
what are cattle MLs
moxidectin
doramectin
eprinomectin
ivermectin
what are the cattle benzimidazoles
albendazole
fenbendazole
oxfendazole
what is forward planning strategic control
FGS weaned calves, set-stocked on same pasture
Commence at 3 weeks after turnout
Can also help control parasitic bronchitis
Compatible with lungworm vaccination
what are examples of forward planning
Ivermectin 3, 8 and 13 weeks after turnout
MLs at turnout and 8 weeks later
Long acting boluses or injection at turnout
when is clinical lungworm disease most commonly seen
young weaned calves
what are sources of dictyocaulus viviparus
over wintered larvae
adult carrier animals
what is the lungworm life cycle
patency after 23 days
lasts 30-40 days
when can clinical signs appear in lungworm
12 days onwards
how is lungworm larval development and dispersion occur
3-4 days in mid summer they develop from L1-L3
Relationship to fungi that grows on fecal pats
Black caps will fling off the fungal hyphae
- The infective larvae will be carried off onto the spore cap
- Can travel ~3m
Rainfall has major effect on dispersal
what are the patterns of lungworm on herbage
End of summer/late summer and early autumn peak of larvae on pasture
Rapid development
Rapid transition from pat to pasture
Rapid mortality
~4 weeks in short swards in hot, sunny conditions
But can survive over winter on pasture
what are the impacts of lungworm
Clinical parasitic bronchitis:
- Respiratory dysfunction
Re-infection syndrome
- Immunopathology
- Respiratory dysfunction
Subclinical infections:
- Production losses
- Carriers
what is the first line of defence to lungworm and how long does it last
Resistance to colonization of lungs by larvae, which are trapped in the mesenteric lymph nodes
Lasts ~6 months
Primed by the vaccine
what is the second line of defence to lungworm and how long does it last
Destruction and elimination of larvae/adults from lungs
Lasts >24 months
when can dictyocaulosis occur in adult cattle
Patent disease in naive animals (zero-grazed, bought in)
Re-infection syndrome, in animals exposed >6 months previously (previous grazing season)
No immune barrier in mesenteric LNs, so larvae get to lungs where they are killed by host immune response in lungs
how is lungworm diagnosed
what are tools for lungworm control
what is the lungworm vaccine
Vaccinate animals older than 8 weeks of age and in good health
Two doses of vaccine 4 weeks apart
Turnout to grass no sooner than 2 weeks after the 2nd vaccination
Avoid the use of anthelmintics from 8 weeks before the 1st dose until 2 weeks after the 2nd dose
what shoud occur after completion of vaccine course of lungworm
After the completion of the vaccination course, calves should graze lightly infected pastures in order to boost immunity
A single dose of vaccine can be given prior to turnout in subsequent years if required
what are limitations to the lungworm vaccine
First grazing season calves PGE
Spring-calving herds/animals
Age of calve
Vaccination at pasture
Availability of vaccine (late turnout)
what are anthelmintics for lungworm control
what are strategic programmes for anthelmintic in youngstock for lungworm
FGS weaned calves, set-stocked on same pasture
Commence at 3 weeks after turnout
Also control PGE
what are examples of strategic programmes for anthelmintic in youngstock for lungworm
Ivermectin 3, 8 & 13 weeks after turnout
MLs at turnout & 8 weeks later
Long acting injection/boluses at turnout
what are anthelmintic treatments for lungworm
what are ddx and treatment failure of lung worm in individuals
secondary infections
resp failure (irreversible lung pathology, stress induced hypoxia)
re infection syndrome
what are ddx and treatment failure of lung worm in groups at pasture
IBR
other bacterial/viral resp pathogens
BRD
