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VMS4008 > Clinical Parasitology of small ruminants & camelids > Flashcards

Clinical Parasitology of small ruminants & camelids Flashcards

1
Q

What main important parasites in cattle & sheep (GIT parasites)

A
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2
Q

Where do each sheep gut parasites affet?

A

Nematodirrus (Small intestine)
Ostertagia/Teladorsagia (Abomasum)
Trichostrongylus (Small intestine)
Haemonchus (Abomasum)

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3
Q

WHEN do sheep parasites happen?

A
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4
Q

Is nematodirus as significant in goats/ camelids as it is in lambs?

A

NO

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5
Q

describe Nematodirus timing & pathogenesis ?

A
  • Hatching requires prolonged chill, then mean temp
    >10oC (late spring)- outbreak May-June
  • Larvae cause disease (migrating and sheading in mucosa)
  • Villous atrophy and fusion
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6
Q

Transmission of nematodirus?

A
  • Lamb to Lamb- last years lamb infecting this years
  • Eggs survive on pasture for a long time
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7
Q

Signs of Nematodirus?

A
  • Diarrhoea
  • Inappetence
  • Reduced growth rates
  • Death
  • Mortality high if untreated
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8
Q

Detailed pathoG of nematodirus?

A

Last years lambs contaminate the pasture ->

Lambs are moved on, eggs rain and overwinter on pasture ->

New season lambs on same pasture ->

Activation of over winted eggs to larvae and consumed in sudden large numbers causing clinical disease ->

Disease in prepatent period = no eggs on FEC

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9
Q

When does Teladorsagia occur?

A
  • July- October
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10
Q

Burdens of teladorsagia related to ?

A

weather patterns and previous Hw of pasture infestation

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11
Q

Transmission of Teladorsagia?

A
  • Infection from ewes with an periparturient rise in FEC
  • Eggs passed by lambs after ingesting overwinter larvae from last years lambs
  • Eggs passed by lambs early in season infect lambs later in
    same season
  • Eggs develop to larvae on pasture
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12
Q

What do we see with teladorsagia before vs after October?

A
  • Before Oct= clinical disease (type 1)
  • After Oct=Larvae arrested (type 2)
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13
Q

Signs of Teladorsagia & Immunity?

A
  • Weight loss, intermittent diarrhoea, poor weight gain in lambs, ill thrift
  • Immunity is acquired slowly (over 2 grazing seasons)
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14
Q

How does initial transmission / high burden happen with teladorsagia?

A
  • SMall population of eggs overwintered ->
  • Peripartum reduction in immunity = increased egg contamination from ewes around lambing ->
  • Eggs develop into larvae about July
  • Lambs now ingesting large numbers of larvae on pasture which were eggs from ewes/overwinter
  • Larvae develop to adults PP-3 weeks so development of CS July-Oct

THEN

Lambs end up infecting the pasture for other lambs in the same cohort due to high burdens of adult worms

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15
Q

When does Haemonchus/ contortus become a problem?

A

Warm/wet weather
July/august

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16
Q

Transmission / high burdens of Haemonchus ?

A
  • Overwintering in the host (ewe) as inactive L3
  • Ewe is source of infection for lambs
  • Outbreaks of disease rely on weather conditions and
    pasture contamination so often sporadic and
    unpredictable
  • No strong immunity by adult animals so any age
    affected
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17
Q

acute dx haemonchus?

A
  • Anaemia, loss of iron and protein in GI tract
  • Submandibular oedema
  • Inappetence, lethargy, high mortality
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18
Q

chronic dx haemonchus?

A
  • Lower exposure over longer period
  • Weight loss, weakness, inappetence
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19
Q

What is Hypobiosis?

A

The developmental adaptation that allows parasites to persist in their host for extended period of time. State of reduced metabolic activity caused by environmental parameters or host resistance.

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20
Q

Which parasites get arrested development?

A
  • Teladorsagia/oestertagia
  • Haemonchus
  • Some Trichostrongylus spp
  • Cooperia (cattle)
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21
Q

What stage will arrest?

A

L4 in autumn within immune host -> contributes to re-infection following year

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22
Q

Weather for coccidiosis?

A

Wet warm weather. Poaching of
ground around troughs

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23
Q

Who does coccidiosis affect ?

A
  • Lambs aged 4-8 weeks old
  • Younger animals affected as
    season progresses
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24
Q

What does coccidiosis cause and what clinical signs ?

A
  • Damage to the intestines
    results in long term impact on
    growth rates
  • Diarrhoea
  • Straining
  • Mucus or blood
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25
Q

What is the multiplier effect? what does this cause?

A

Lambs shed millions more oocysts of coccidia than they eat ->

Immunity increases with exposure. Naive lambs at risk of severe dx

26
Q

What weather for fluke?

A

Increasing rainfall, acute
fluke in weaned lambs seen
autumn

27
Q

Lifecycle of fluke ? which important intermediate host?

A

SNAILS

28
Q

What faecal exam can we do for what worms?

A
29
Q

How to interpret FEC for Nematodirus?

A
  • Nematodirus= FEC not strongly linked to
    worm burden- egg production/worm is higher
    when there are fewer worms
  • Egg counts with N battus is usually low when
    acute infection as the disease is from prepatent period
  • Low egg counts of N battus may still be
    significant
30
Q

FEC for haemonchus interpretation?

A

H contortus egg counts can be very highworms have very high fecundity.

31
Q

General FEC interpretation ?

A
  • FEC in older animals is a less reliable indicator
    of burden
  • FEC are only representing the worms which
    picked up 3-4 weeks ago and not current
    ingestion/larval burden
32
Q

Famcha chart for haemonchus?

A
33
Q

What are the categories of ‘broad spec’ Anhelmintics?

A
34
Q

Describe White drench?

A
  • Broad spectrum
    anthelmintics
  • Cover against
    nematodes
  • Including lungworm
  • Some cover against
    Tapeworm
  • No ectoparasite cover
  • Significant resistance seen
35
Q

Which White Wormer has narrow spectrum?

A

Triclabendazole - liver fluke only

36
Q

What do Levimasoles cover?

A
  • Covers nematodes
  • Including lungworm
  • No cover against tapeworm
  • No cover against fluke
  • No cover against ectoparasites
  • Limited efficacy against encysted larval stages (Ostertagia)
  • Significant resistance seen
37
Q

Therapeutic safety index with Levamisole?

A
  • Therapeutic safety index is low
  • Impacts on nerve ganglion causing salivation, bradycardia, muscle tremors
  • It is not ovicidal (doesn’t kill eggs)
38
Q

What wormers are MAcrocyclic lactones?

A
  • Avermectins -> Ivermectin, doramectin
  • Milbemycins -> Moxidectin
39
Q

What do macrocyclic lactones cover?

A

NEMATODES
- Including lungworm
- Cover extoPs

NO COVER for:
- Tapeworm
- Fluke

SIG Resistance

40
Q

WHat do orange (Amino-acetonirile derivates) wormers cover?

A
  • Effective against NEMATODES * Even those resistant to other groups

NO cover for:
- Lungworm
- Fluke
- Tapeworm
- EctoP

41
Q

What do Purple (Sporoindoles) wormers cover?

A
  • Dual active preparation
  • Abamectin + Spiroindole= Derquantel
  • Covers nematodes
  • Including lungworm

NO cover of:
- Tapeworm
- Fluke
- EcctoPs

42
Q

What narrow spectrums Anthelmintics do we have?

A
  • Phenols = Nitroxynil
  • Salicylanilides =closantel and oxyclozanide
43
Q

What are narrow specs effective against?

A
  • Fluke
  • Haemonchus
44
Q

What else does Salicylanilides cover?

A

soem ectoPs

45
Q

Closantel is an … formulation

A

oral

46
Q

Nitroxynil is an …… formulation -> it ……. goats

A

Injectable ; It KILLS Goats !!!

47
Q

WHat combination with triclabendazole?

A

2-LV, 3-ML

48
Q

What combination wormer si common?

A

Closantel & 3-ML

49
Q

USe of combination wormers?

A
  • Often used as assurance even if not both required
  • Leads to off target selection for resistance to broadspectrum anthelmintics in nematodes or fluke
  • Some evidence that combination wormers may improve
    efficacy on resistance fluke or haemonchus populations
50
Q

What worms resistant to what wormers?

A
51
Q

What is an FECRT?

A

Faecal egg count reduction test

52
Q

How to do a FECRT?

A
  • Day1 = dose with wormer, separate group and dose with each wormer if necessary
    = take FEC
  • Day 7= if dosed with 2-LV = FEC
  • Day 14=If dosed 1-BZ, 3-ML= FEC
53
Q

When is resistance suspected with FECRT?

A

if less than 95% reduction in burden

54
Q

What are the SCOPS Principles?

A
  1. Establish a parasite control strategy with your vet
  2. Avoid introducing resistant worms
    - Quarantine treatments (monepantel + moxidectin)
    - House on concrete for 24hrs
    - Move to contaminated pasture
  3. Annual test for anthelmintic resistance (FECRT / DTs)
  4. Administer anthelmintics effectively
    - Check dosing equipment
    - Dose for the heaviest sheep
  5. Use anthelmintics only when necessary
    Avoid treating immune animals
    Do not dose routinely at tupping
    ONLY dose poorly conditioned ewes at lambing
  6. Selecting the appropriate anthelmintic
  7. Preserve susceptible worm population (in refugia)
    DO NOT ‘dose-and-move’
    Avoid routine dosing
    Leave ~10% untreated
  8. Reduce dependence on anthelmintics
55
Q

How to AVOID introducing new worms?

A
56
Q

How do we administer anthelmintics effectively?

A
57
Q

When should we NOT dose animals?

A

AT TUPPING!
- Selective dosing - poor condition - low FAMSHA scores

58
Q

Should we dose at turnout (peripartum) ?

A
  • Complicated
  • Peripartum relaxation of immunity (PPRI)
  • FEC rise
  • High FEC=Greater parasite challenge for lambs- want to reduce this
  • BUT- dosing early in PPRI= no change in FEC rise
  • Dosing late= prolonged period before reinfection of the ewe with in-refugia population= highly
    selective for AR
59
Q

Combination produts - what not to use together?

A

Broad spec wormer + flukicide in fluke only control

60
Q

How can we reduce dependence on anthlemintics?

A
  • Avoid conventional suppressive treatment strategies
  • Use grazing management
  • Use rams bred for resistance to worms to improve
    genetic immunity in flock
  • Chose forage/leys that have anthelmintic properties
  • Chickory

VMS4008 (42 decks)

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