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Y4 FA - Small ruminants > Nematode and cestode infections in sheep > Flashcards

Nematode and cestode infections in sheep Flashcards

1
Q

What are the roles of vets when there are nematode/cestode infections in sheep?

A
  • Devising worm control strategies (Flock Health Plans)
  • Advising on outbreak parasitic disease occurs
  • Advising on poor growth in lambs/ thin ewes
  • Advising when anthelmintic resistance problems occur
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2
Q

What are the 3 main current problems with parasite control in sheep?

A
  • Drug resistance
  • Climate change
  • Parasites
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3
Q

Describe how drug resistance is becoming a major problem with parasite control in sheep

A
  • Maintaining high levels of production relies on heavily stocked pasture and intensive anthelmintic use
  • Inappropriate use of anthelmintics
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4
Q

Describe how climate change is becoming a major problem with parasite control in sheep

A

Mild winters warmer spring summer increased new species and increased parasite numbers on pasture

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5
Q

How is anthelmintic resistance defined?

A

Defined as drug <95% efficacy

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6
Q

What can be done about anthelmintic resistance?

A
  • Devise sustainable parasite control plans
  • Reduce selection pressure to slow progression of resistance
  • Improve biosecurity to prevent introduction of resistant strains
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7
Q

How do nematode infections cause clinical disease in sheep?

A
  • Damage lining of guts (reducing absorption)
  • Remove nutrients
  • Remove blood (Haemonchus)
  • Host immune response (host resources and damage)
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8
Q

What are the overall clinical signs of nematode infections in sheep?

A

Reduced appetite. Poor weight gain/ weight loss
Submandibular oedema
Diarrhoea
Anaemia
Death

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9
Q

Outbreaks of acute severe diarrhoea and death lambs 6-12 weeks old are caused by which nematode infection?

A

Nematodirus battus

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10
Q

Describe type I and II Teladorsagia infections

A

Type 1: Lambs first grazing season, mid summer onwards
Type 2: yearlings winter months, emergence of hypobiotic larvae

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11
Q

Lambs with black scour occurring the the late summer/autumn months is caused by which nematode?

A

Trichostrongylus

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12
Q

What are the signs of Haemonchus contortus infections?

A

Adults and lambs
Acute regenerative anaemia
Chronic hypoproteinaemia, anaemia bottle jaw
Sudden death

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13
Q

How long does is take for the egg to develop into L3 in:
1. early spring
2. early summer

A

1 = 10-12 weeks
2 = 1-2 weeks

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14
Q

Development L3 to eggs in sheep takes how long?

A

16-21 days

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15
Q

Which nematode spp numbers peak in early summer?

A

Teladorsagia

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16
Q

Which nematode spp numbers peak in late summer/autumn?

A

Trichostrongylus

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17
Q

Describe hypobiosis

A

L3 late autumn early winter over winter period interrupted development L4 stage inside sheep

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18
Q

What is the consequence of hypobiosis?

A

Pasture contamination in spring and early summer

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19
Q

Describe the epidemiology of N.battus

A
  • Eggs shed by lambs one year, remain on pasture and infect next year lambs
  • Mass hatching of L3
  • Severe outbreaks of diarrhoea in 6-12 week old lambs
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20
Q

When does hatching/release of N.battus eggs occur?

A

Prolonged period of chill followed temperature range of 10C-18C leads to large numbers of L3 hatching simultaneously

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21
Q

Describe sheep immunity to nematodes

A

Providing they have been exposed to nematodes LAMBS should be developing resistance to nematodes around 5-6 mo

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22
Q

Immunity to nematodes is influenced by which factors?

A

Nutrition (protein)
Genetics (opportunity breeding)
Stage of production

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23
Q

What does SCOPS stand for?

A

Sustainable control of parasites in sheep

24
Q

Which anthelmintics are described as ‘white drench’?

A

Benzimidazoles

25
Q

What is the function of benzimidazoles?

A

Tubulin binding, prevents uptake of glucose, ovicidal (kills eggs)

26
Q

Describe use/resistance to benzimidazoles

A
  • Broad spectrum
  • N.battus resistance reported
  • More resistance so may not work
27
Q

Which anthelmintics are described as ‘yellow drench’?

A

Levamisole - imidazothiazines

28
Q

What is the function of levimisole?

A

Ganglion blocking drugs, paralysis not ovicidal

29
Q

Which anthelmintics are described as ‘clear drench’?

A

Macrocytic lactones

30
Q

What is the action of macrocytic lactones?

A

Block Cl- and GABA channels -> paralysis

31
Q

All injectable forms of which anthelmintic are active against mange mites (sheep scab)

A

Moxidectin (MLs)

32
Q

Which group of anthelmintics are known as ‘orange drenches’?

A

Amino-acetonitrile

33
Q

Which group of anthelmintics are known as ‘purple drenches’?

A

Spiroindoles

34
Q

How should group 4 and 5 (new generation) antibiotics be used?

A

Do not keep for best, should be used regularly as part of drug rotation in worm control plan, especially useful at quarantine dose

35
Q

Key factors influencing the development of Anthelmintic Resistance in a population are?

A
  • Treatment frequency
  • Under dosing
  • Biosecurity: new strains introduced
  • Proportion of population exposed to treatment “in refugia”
36
Q

How can you detect that resistance is present?

A

Clinical signs:
- Lamb growth rates reduced - EID regular weighing DLWG really useful
- Diarrhoea
- Death

37
Q

Which test can be used to know if resistance is present?

A

Faecal Egg Count Reduction Test - should be reduced to zero after administration of drug. If reduction is 95% or less, resistance has been detected.

38
Q

Describe how to carry out the faecal egg count reduction test

A
  • 10 lambs per group - Weigh and mark
  • Pre-treatment FEC
  • Accurate dose drug
  • 7-14 days post treatment (depending on drug used) FEC
39
Q

Describe the drench test

A

(cheaper quicker less accurate) post treatment FEC check
* FEC 7-14 days post treatment (depending on drug)
* Pooled worm egg count

40
Q

What are the 4 SCOPS principles?

A
  1. Always make sure treatment is fully effective
  2. Reduce dependence on anthelmintics using management and monitoring
  3. Avoid bringing in resistant worms and/or other parasites by following a robust quarantine routine. Test for anthelmintic resistance
  4. Minimise the selection for worms that are resistant to anthelmintics when you treat sheep.
41
Q

How can you avoid under-dosing?

A
  • Pick the heaviest sheep in group, weigh it - If big range in sizes then sub group
  • Check dosing gun
  • Test for resistance
  • Make sure you are using the correct product for the task
42
Q

Adult sheep should have immunity to all but which nematode?

A

Haemonchus contortus

43
Q

Why are adult sheep treated?

A

To reduce pasture contamination for lambs

44
Q

Which adult sheep should be treated?

A

only treat thin sheep, triplet bearing ewes, shearlings ewe lambs, ie not fit singles, twin bearing ewes - not routine to dose everything

45
Q

When are adult sheep treated for nematode infections?

A

At tupping time

46
Q

Barbervax is used for?

A

Haemonchus

47
Q

How can management of growing lambs be used to reduce anthelmintic use?

A
  • Rotational grazing
  • Leave ewes on high risk pastures
  • Good nutrition
  • Manage concurrent disease
  • Genetic selection
  • Vaccination program
48
Q

Why cant faecal egg counts be used to target treatment for N.battus?

A

Larval stages causing disease can cause false negatives

49
Q

How is forecasting used for N.battus

A

Temperature conditions across the country indicate when the risk is
Preventative dosing with BZ wormer (white drench)

50
Q

How are brought in sheep managed to avoid bringing in resistant worms?

A

Dose with monopantel
Hold off pasture 24-48 hours allow treatment to work
Return to contaminated pasture

51
Q

When will lambs not need to be wormed?

A

If they are growing at their required growth rates

52
Q

What is the FAMANCHA test for Haemochus?

A

Use pallor of eye mucous membranes. Pale = dose!

53
Q

What are the other clinical signs of Haemonchus infections?

A

Weakness, Collapse, Hyperpneoa, Tachycardia, Sudden death

54
Q

Describe ‘in refugia’

A

If we dose the sheep with anthelmintic when the majority of worm population is in the sheep, ie when free living population is lowest rapidly select for resistance.

55
Q

When are the ‘in refugia’ times of the year?

A

Autumn
Winter
Early spring

56
Q

What are the effects of cestode infections in sheep?

A

Carcass condemnation
Echinococcus granulosus is zoonotic
Gid cysts in the brain

57
Q

The sheep is the final host of which tapeworm infection?

A

Monezia expansa

Y4 FA - Small ruminants (18 decks)

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