Nematodes of Cattle Flashcards by Kayla Stauffer

what parasites affect the abomasum in cattle

Haemonchus

Ostertagia

Trichostrongylus axei

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what are species that affect the small intestine of cattle

Cooperia

Trichostrongylus

Nematodirus

Bunostomum

Strongyloides

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what are species that affect the large intestine of cattle

Chabertia

Trichuris

Esophagostomum

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what are species that affect the lungs of cattle

dictyocaulus

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what are species that affect the eye of cattle

thelazia

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what are species that affec the connective tissue of cattle

Onchocerca

Parafilaria

Stephanofilaria

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what are the most common nematodes of temperate regions

cooperia oncophora
ostertagia ostertagi
dictyocaulus viviparus

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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

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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

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what role does gastrin play in appetite control

Parasite impact on appetite: gastrin increases —> negative feedback on appetite (decrease DMI)

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what affect does PGE have on calves at pasture

decreased growth

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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

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how long does it take for immunity to develop against cooperia

one full grazing season

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how long does it take for immunity to develop against ostertagia ostertagi

two full grazing seasons

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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

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what are immune effects on host biology

Clinical disease

Pathology

Pathophysiology

Behaviour

Productivity

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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

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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

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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)

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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

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what are PGE markers and monitoring strategies

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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

1. Limit exposure of cattle to infection 2. Mitigate impact 3. 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