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PMVPH > Parasitism in Grazing Animals > Flashcards

Parasitism in Grazing Animals Flashcards

1
Q

What are the 4 most important internal parasites in grazing animals?

A
  1. nematodes
  2. liver fluke (ruminants inc. camelids)
  3. lungworm
  4. cocciddia
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2
Q

What is the PPP of nematodes?

A

~ 3 weeks

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3
Q

When is the best larval development of nematodes? What can larvae not survive?

A
  • Warm and moist late autumn/summer

- L can survive freezing but not dessication

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4
Q

Outline the liver fluke lifecycle

A
  • eggs shed in feaces
  • miracidium -> snail
  • cercariea out of snail onto veg
  • metacercariae encycts on veg and is eaten
  • immature fluke migrates to liver
  • mature fluke in liver
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5
Q

Where are the majority of the nematode population found?

A
  • On pasture, 95% within bottom inch of herbage

- 80% eggs passed from 20% animals

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6
Q

What is the succession of species?

A 
Order that helminth worm numbers are highest thoughout the season
> April/July - N. Battus 
> June/Nov - Ostertagia
> July/Nov - Haemonchus
> Sept/Dec - Trichostrongylus
> Sept/Dec - Acute Fluke
> Jan/March - Chronic Fluke
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7
Q

What are the major nemotodes of the abomasum and SI in ruminants?

A 
>Abomasum = HOT! 
Heamonchus contortus (2cm)
Ostertagia (1cm)
Teladorsagia (0.5cm)
>Small Intestine
Trichostrongylus
Nematodirus
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8
Q

What is the major trematode affecting ruminants?

A

Fasciola hepatica (liver fluke)

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9
Q

Which is the main cestode to affect ruminants? Where does it live in GIT and how is it picked up?

A

Moniezia - SI from pasture mites

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10
Q

What clinical and subclinical effects may nematodes have?

A 
> clinical 
- D+, weight loss, death
> sub clinical
- v weight gain 
- all animals affected 
- LOP
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11
Q

How do nematodes produce pathologic effects?

A
  • reuced appetite most important
  • change in GIT structure and function
  • immune and inflam responses
  • malabsoprtion
  • energy cost of immune response
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12
Q

How does PGE -> protein loss?

A
  • ^ secretion mucous and IgA
  • ^ mucosal permeability allowing protein leakage
  • local Ag/Ab reaction in gut - vasodilation
  • ^ cell turnover in mucosa
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13
Q

What effects does haemonchus cause? What test can be used to quantify this?

A
  • anaemia (blood sucking)

- FAMACHA test

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14
Q

What are the harmful effects of trematodes?

A

> Acute - liver damage

> Chronic - blood and protein loss, hyperplasia of bile ducts

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15
Q

Which age of animal are often affected by parasitism and why?

A

Young

- Adults develop an immunity (in most cases)

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16
Q

In which cases may adults not be immune from parasitism?

A
  • goats
  • immunocompromised
  • ewes after lambing (PPRI periparturient relaxation in immunity)
  • liver fluke
17
Q

What is the main source of parasite infections/risk in SPRING?

A

> Nematodirus battus
- Mainly overwintered on pasture
- Some from adult animals
Type 2 ostertagiosis in young cattle

18
Q

Is FEC useful in diagnosing spring problems?

A

NO! PPP = 3 weeks, nothing will be seen in faeces

19
Q

What is the main source of parasite infections/risk in SUMMER?

A

> Subclinical effects of PGE/BOVINE OSTERTAGIOSIS

  • young susceptable animals grazing
  • larval no ^
  • liver fluke eggs hatch
  • autoinfection peak
  • nematodes in calves, lambs and goats
  • Teladorsagia mainly (sheep/goats)
20
Q

What is the main source of parasite infections/risk in AUTUMN?

A

> SUBCLINICAL EFFECTS PGE

  • peak in pasture nematode larval levels
  • liver fluke metacercariae in snails
  • nematodes in calves, lambs and goats
  • Tricholstrongylus mainly (sheep/goats)
  • acute fasciolosis (from ingestion of millions of metacercariea -> immature fluke tracks in liver)
21
Q

What is the main source of parasite infections/risk in WINTER?

A
  • immunity developing in young animals
  • larval development halted
  • liver fluke develpoing to adults
22
Q

How can endoparasite related pathology be controlled?

A
  • limit exposure of susceptable animals to large number of larvae (ie. avoid autoinfection peak)
  • anthelmintics to break parasite lifecycle
  • “safe” pasture (graze horses/other spp. graze adults, long pasture to dilute worm burden, hay/silage aftermath good)
  • minimise no. susceptable animals (sell lambs early!!)
23
Q

Who has provided guidelines for sustainable parasite control in sheep and cows?

A

SCOPS and COWS

24
Q

What are the 5 main clases of anthelmintic?

A
  1. White Benzamidazoles
  2. Clear Macrocytic Lactones
  3. Yellow Levamisoles
  4. Orange Aminoacetonitrile derivatives
  5. Purple Spiroindoles
25
Q

What are the main threats to ruminants from parasites in spring, summer/autumn and winter?

A

> Nematodes and liver fluke

  • Spring: arrested and overwintered larvae
  • summer/autumn: PGE
  • winter: liver fluke
26
Q

What is the equivalent of ostertagia in cattle in sheep?

A

Teladorsagia

27
Q

What does N. battus cause?

A

Sudden death of lambs with no eggs on FEC as before PPP

28
Q

Deinfe the pre-patent period

A

Time between ingestion and production of eggs in feaces

29
Q

What must be remembered with parasite lifecycles?

A

Grazing periods and weather patterns are changing

30
Q

What clinical sign may be associated with liver lfuke?

A

Bottle jaw

31
Q

Is immunity to liver fluke good?

A

No

PMVPH (20 decks)

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