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Module 18: Ruminant Production > Nematodes of Cattle > Flashcards

Nematodes of Cattle Flashcards

1
Q

what parasites affect the abomasum in cattle

A

Haemonchus

Ostertagia

Trichostrongylus axei

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2
Q

what are species that affect the small intestine of cattle

A

Cooperia

Trichostrongylus

Nematodirus

Bunostomum

Strongyloides

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3
Q

what are species that affect the large intestine of cattle

A

Chabertia

Trichuris

Esophagostomum

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4
Q

what are species that affect the lungs of cattle

A

dictyocaulus

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5
Q

what are species that affect the eye of cattle

A

thelazia

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6
Q

what are species that affec the connective tissue of cattle

A

Onchocerca

Parafilaria

Stephanofilaria

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7
Q

what are the most common nematodes of temperate regions

A
  1. cooperia oncophora
  2. ostertagia ostertagi
  3. dictyocaulus viviparus
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8
Q

what are abomasal lesions that ostertagia ostertagi cause

A

Gastric gland with hyperplastic change

Loss of cellular differentiation

Central orifice marking exit of worm

Resolution over ~2 months

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9
Q

what is the host response to ostertagia ostertagi

A

HCl secretion reduced: pH increases

gastrin is secreted

pepsinogen does not convert to pepsin

leads to

hypergastrinemia

pepsinogen increases

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10
Q

what role does gastrin play in appetite control

A

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

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11
Q

what affect does PGE have on calves at pasture

A

decreased growth

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12
Q

what is inhibited larvae and ostertagiosis type II

A

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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13
Q

how long does it take for immunity to develop against cooperia

A

one full grazing season

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14
Q

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

A

two full grazing seasons

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15
Q

what are immune effects on parasite biology

A

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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16
Q

what are immune effects on host biology

A

Clinical disease

Pathology

Pathophysiology

Behaviour

Productivity

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17
Q

how do ostertagia and cooperia develop and disperse on pasture

A

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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18
Q

what is the longevity of PGE larvae on herbage

A

Majority of larvae disappear within 12 months

Some survive to 24 months

Soil may act as a reservoir

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19
Q

what is the seasonality of PGE in weaned dairy calves

A

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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20
Q

what is the seasonality of PGE in beef calves

A

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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21
Q

what are PGE markers and monitoring strategies

A
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22
Q

what is the problem with using fecal egg counts as PGE markers and monitoring

A

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

23
Q

why is albumin useful in PGE marker and monitoring

A

Albumin is useful because it gives indication of protein loss in GI tract associated with Ostertagia lesion in abomasum

24
Q

what is the first marker of decreased performance in PGE

A

decreased DLWG

25
Q

how is PGE controlled through grazing management

A
  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
26
Q

what is high risk pastures for PGE

A

grazed by cattle <1 year old within last year

permanent pasture

27
Q

what is medium risk pastures for PGE

A

permanent pastures grazed by cattle 1-2 years old within last year

silage/hay aftermath: grazed by cattle <1 year old the same year

28
Q

what are low risk pastures

A

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

29
Q

what are cattle MLs

A

moxidectin

doramectin

eprinomectin

ivermectin

30
Q

what are the cattle benzimidazoles

A

albendazole

fenbendazole

oxfendazole

31
Q

what is forward planning strategic control

A

FGS weaned calves, set-stocked on same pasture

Commence at 3 weeks after turnout

Can also help control parasitic bronchitis

Compatible with lungworm vaccination

32
Q

what are examples of forward planning

A

Ivermectin 3, 8 and 13 weeks after turnout

MLs at turnout and 8 weeks later

Long acting boluses or injection at turnout

33
Q

when is clinical lungworm disease most commonly seen

A

young weaned calves

34
Q

what are sources of dictyocaulus viviparus

A

over wintered larvae

adult carrier animals

35
Q

what is the lungworm life cycle

A

patency after 23 days

lasts 30-40 days

36
Q

when can clinical signs appear in lungworm

A

12 days onwards

37
Q

how is lungworm larval development and dispersion occur

A

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

38
Q

what are the patterns of lungworm on herbage

A

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

39
Q

what are the impacts of lungworm

A

Clinical parasitic bronchitis:

  • Respiratory dysfunction

Re-infection syndrome

  • Immunopathology
  • Respiratory dysfunction

Subclinical infections:

  • Production losses
  • Carriers
40
Q

what is the first line of defence to lungworm and how long does it last

A

Resistance to colonization of lungs by larvae, which are trapped in the mesenteric lymph nodes

Lasts ~6 months

Primed by the vaccine

41
Q

what is the second line of defence to lungworm and how long does it last

A

Destruction and elimination of larvae/adults from lungs

Lasts >24 months

42
Q

when can dictyocaulosis occur in adult cattle

A

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

43
Q

how is lungworm diagnosed

A
44
Q

what are tools for lungworm control

A
45
Q

what is the lungworm vaccine

A

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

46
Q

what shoud occur after completion of vaccine course of lungworm

A

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

47
Q

what are limitations to the lungworm vaccine

A

First grazing season calves PGE

Spring-calving herds/animals

Age of calve

Vaccination at pasture

Availability of vaccine (late turnout)

48
Q

what are anthelmintics for lungworm control

A
49
Q

what are strategic programmes for anthelmintic in youngstock for lungworm

A

FGS weaned calves, set-stocked on same pasture

Commence at 3 weeks after turnout

Also control PGE

50
Q

what are examples of strategic programmes for anthelmintic in youngstock for lungworm

A

Ivermectin 3, 8 & 13 weeks after turnout

MLs at turnout & 8 weeks later

Long acting injection/boluses at turnout

51
Q

what are anthelmintic treatments for lungworm

A
52
Q

what are ddx and treatment failure of lung worm in individuals

A

secondary infections

resp failure (irreversible lung pathology, stress induced hypoxia)

re infection syndrome

53
Q

what are ddx and treatment failure of lung worm in groups at pasture

A

IBR

other bacterial/viral resp pathogens

BRD

Module 18: Ruminant Production (25 decks)

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