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Small Ruminants Medicine and Production > Lecture 9 and 10 > Flashcards

Lecture 9 and 10 Flashcards

1
Q

Explain the lifecycle of GI nematodes

A

L3 = infective stage

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2
Q

What is the requirements for GI nematodes

A

Low temperature

Moisture

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3
Q

What is the prepotent period for GI nematodes

A

3 weeks

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4
Q

What are some species that undergo hypobiosis

A

Telodorsagia circumcinctia - larvae ingested in late winter and early spring -> resume development in autumn
Haemonchus contorts -> larvae ingested in winter and autumn -> resume development in spring

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5
Q

What occurs in winter rainfall sones

A

Telodorsagia circumcincta and Trichostrongylus
Nematodirus
Harmonchus contortus

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6
Q

What occurs in summer rainfall zones

A

Haemonchus contorts

Telodorsagia circumcincta and Trichostrongylus

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7
Q

Effects of GI nematodes on sheep

A

Reduce appetite, skeletal growth, haemopiesis, protein and mineral metabolism
Subclinical
- Reduced body growth
- Reduced wool production

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8
Q

What are the clinical signs of GI nematodes

A

Sudden death, Anaemia, Bottle Jaw, Loss of appetite, weight loss, diarrhoea, death

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9
Q

Explain immunity to GI parasites in lambs

A

Timing of development of natural immunity depends on rate larval intake -> exposure to larvae is needed to build up natural immunity
Most immunity is acquired by 18 months

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10
Q

Explain GI immunity in mature sheep

A

Once developed, immunity remains strong against against most scour worms -> low worm burden
Exception: H.contortus developed immunity is less strong and reliable
Natural immunity may break down if extreme larval pressure and/or poor nutrition

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11
Q

How to diagnose GI nematodes

A

History, Clinical signs, Worn egg count, haemonchus dip stick, WEC with larval differentiation, Total worm count, ELISA, Blood pepsinogen

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12
Q

What are the potential problems with a worm eggs count

A

Unreliable indicators of the size of an adult worm burden and the severity of pasture infection

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13
Q

What is the diagnostic purposes of the Worm Egg Count

A
  • Estimate size of burden -> immediate treatment, not treatment, re-sampling in short term
  • Degree of pasture contamination occurring at time of testing
  • Assessment of anthelmintic efficacy
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14
Q

What is seen with a PM of GI nematodes

A

Acute and chronic liver fluke lesions

200 adult flukes -> chronic disease symptoms

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15
Q

Explain the Barbervax vaccine program

A

New tool to protect sheep against barber pole

  • SC injections at not more than 6 weekly intervals
  • Monitor WEC 4-5 weeks after vaccination to assess if drench is needed at next muster
  • Breeding worm resistant sheep + grazing management will enhance effectiveness of vaccination
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16
Q

What is anthelmintic resistance

A

Ability of parasites to survive doses of drugs that would normally kill parasites of the same species and age

17
Q

How does anthelmintic resistance develop

A
  • Under dosing
  • Frequent drenching
  • Use of single active drenches
  • Persistent anthelmintics
  • Ecological interactions with drenching
18
Q

How to detect anthelmintic resistance

A

Drench check: WormTest with larval differentiation before and after drench
DrenchTest/WECRT: WEC and larval differentiations of each treatment group are compared with those underenched control group
Total worm count

19
Q

What are the consequences of drench resistance

A

Reduces effectiveness of long-term control programs

Reduces ability to treat clinical disease

20
Q

How to manage drench resistance

A
  • Regular drench resistance testing
  • Use combination products
  • Do not under dose
  • Use short acting products
  • Quarantine drench to any introduced sheep
  • Develop an effective worm control program
  • Maintain a proportion of the worm population in refugia
21
Q

Explain a quarantine drench

A
  • Avoids bringing drench-resistance strains onto a farm
  • Use a combination of minimum 4 unrelated drench active with at least of these being the newest drench activity: monepantel or derquantel +/- liver fluke treatment
  • Hold sheep in secure quarantine paddocks
  • Perform WormTest 14 days after drenching
22
Q

What is integrated parasite management

A
  • The right drench at the right time
  • Paddock/grazing management
  • Use Barbervax vaccine for Barberpole worm
  • Maintain good nutrition
  • Flock and weaner management
  • Worm resistant sheep
  • Biological control
  • Fine-tuning based on sound information
23
Q

How to prepare a low worm risk paddock

A

Allow time for most of the existing work eggs and larvae to die
Prevent more worms contaminating pastures

24
Q

What are the tactical and strategical treatments

A
  1. Curative drench
    - If severe clinical signs
    - Highly effective drench needed + more sheep to safer pasture if possible
  2. Tactical drench
    - Short term response to overt or imminent outbreaks of pasasitism, based on WEC
  3. Strategic drench
    - Effect levels of pasture contamination later in the season for the benefit of the whole mob +/- immediate production benefit
25
Q

What is strategic drenching

A 
Summer drenching program:
- 1st summer drench: Nov/Dec
- Monitor WEC in Jan/Feb 
- 2nd summer drench: feb 
Weaning drench 
- Drench and wean at 14 weeks after lambing + move to weaning paddock
26
Q

What are the acute signs of fasciola hepatica

A
  • Severe liver damage
  • Found dead in the paddock
  • Most common in young sheep in summer and early autumn
27
Q

What are the subacute signs of fasciola hepatica

A
  • Jaundice, ill-thrift, anaemia and possible death after certain weeks
28
Q

What are the chronic signs of fasciola hepatica

A
  • Mature flukes in bile ducts +/- immature flukes in the liver
  • Illthrift, anorexia, anaemia, bottle jaw
  • Most common in adult sheep in winter
29
Q

What are the subclinical signs of fasciola hepatica

A

Reduced wool production and body growth

30
Q

What is Black disease

A
  • Clostridium novae type B
  • Most common in summer and early autumn
  • Rapid course of disease
31
Q

How to treat fasciola hepatica

A

Grazing management

Flukicides: triclabendazole, closantel, abendazole

32
Q

How are sheep infected with tape worm

A

Faecal-oral route - needs and intermediate host -> free living pasture mites

Small Ruminants Medicine and Production (6 decks)

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