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sheep/goat class > sheep nematodes > Flashcards

sheep nematodes Flashcards

1
Q

what are the 2 gastrointestinal nematodes that we have to know for SR?

A

haemonchosis –> Haemonchus contortus [causes anemia]

Parasitic gastroenteritis –> Teladorsagia, Trichostronglus, etc –> causes D+

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2
Q

what coccidia do we have to know for SR?

A

Eimeria spp.

D+ and/or dysentery

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3
Q

the integrated approach to parasite control in sheep is using _____ + _____.

A

grazing mgmt + targeted anthelmintic treatments

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4
Q

tell me about the epidemiology of ovine GI nematodes in NAm

A

Clinical disease occurs from July-Oct (maybe Nov-Dec but these are not included in the graph lmao)

infective L3 on pasture skyrockets in July, peaks in Aug, lowers from Sept-Oct

eggs in ewe feces peaks in March, lowers after that

eggs in lamb feces increases from May-July, peaks in Aug, then lowers

lambs begin to graze in Apr-May

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5
Q

what are the 2 sources of infective L3s?

A
  1. on pasture from previous grazing
  2. from eggs deposited by animals
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6
Q

what is the aim of grazing mgmt?

A

graze sheep on pastures with lowest risk of contamination with infective larvae

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7
Q

what is important to know about turning sheep out into pastures in spring?

A

some ovine parasitic nematode larvae overwinter in western Canada!

Teladorsagia + Trichostrongylus overwinter
- haemoncus does not

overwinter L3s usually die off by mid-summer if pasture not grazed

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8
Q

describe a risk assessment of moving sheep onto pastures in spring/early summer

A
  1. was the pasture grazed by sheep/goats in the previous year?
    - if no –> very low risk pasture
    - if yes, refer to 2.
  2. were those sheep likely to have resulted in high levels of pasture contamination that overwintered?
    - if no (ex. non-lactated ewes or yearlings with good parasite control/low FECs) –> low risk of GIN L3 larvae on pasture
    - if yes (ex. ewes/lambs w poor parasite control/high FEC) –> high risk of GIN L3 larvae on pasture (except for haemonchus)
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9
Q

describe a risk assessment of moving sheep onto pastures in late summer/early fall

A
  1. was the pasture grazed by sheep/goats earlier that season?
    - if no –> low risk grazing
    - if yes –> refer to 2.
  2. were those sheep likely to have results din high levels of pasture contamination that overwintered?
    - if no –> low risk of GIN L3 larvae on pasture
    - if yes –> high risk of GIN L3 larvae on pasture (including haemonchus!)
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10
Q

true or false: even if a pasture is “safe/low risk”, animals are a potential source of pasture contamination (ex. adult worms, reactivating inhibited larvae)

A

true

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11
Q

true or false: regular monitoring with FEC is needed to build up a picture of pasture contamination and help inform grazing mgmt

A

true

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12
Q

when is it important to perform FEC especially?

A

ewes in spring
lambs in fall

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13
Q

what is important to remember when using rotational grazing in relation to GIN epidemiology?

A
  • for haemonchus infective larvae to appear on pasture, can be as little as 1 week in optimal conditions, and as long as 1 mo or longer in less optimal conditions
  • quicker in mid-summer than in spring or fall. delayed if little precipitation
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14
Q

true or false: it is important to avoid overgrazing because 90% of parasite larvae are in bottom 4 inches of grass

A

true

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15
Q

true or false: infective larvae may be in higher numbers and appear on pastures quicker during the summer than during the spring or fall.

A

true

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16
Q

true or false: it is a good GIN control strategy to alternate sheep and goats on a pasture.

A

false

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17
Q

true or falsE: pastures are usually safe during spring as infective larvae die during winter on western Canadian pastures

A

false

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18
Q

True or false: as the GIN lifecycle lasts 21 days, if a pasture does not have sheep for 2 mo, it can be considered free of infective L3 contamination

A

false

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19
Q

true or false: rotation grazing strategies need to be considered together with GIN epidemiology and risk assessment of pastures.

A

true

20
Q

what are the 2 major broad spectrum classes of anthelmintics used in sheep in Canada over the last 30 years? is anhelmintic resistance widespread in either of them?

A
  • benzimidazole (fenbendazole, albendazole)
  • macrocyclic lactone (ivermectin)

resistance widespread in both!!

21
Q

moxidectin is a _______ that is not licensed, but is starting to be imported from the US in the last few years. Clinical anhelmintic resistance is ____.

A

macrocyclic lactone, rare

22
Q

Closantel is an anhelmintic drug newly licensed in Canada. Resistance is ______ in Canada due to _____.

A

rare, due to lack of use (but resistance is common elsewhere it is used)

23
Q
  1. Benzimidazoles, levamisole, ivermectin, doramectin, and closantel: what is the persistence in sheep?
  2. is there persistence in sheep for moxidectin?
  3. what route of admin for anthelmintics is preferred in sheep? why?
A
  1. no persistance
  2. yes
  3. oral. increase effectiveness, injectable can lead to prolonged sub-therapeutic dose (risk factor for resistance)
24
Q

true or false: you should only give ewes anthelmintics,

A

false. both ewes and lambs are sources of pasture contamination so you should give to both

25
Q

true or false: you should use “recipe-based” anthelmintic use approach. why or why not?

A

false!! do not do this!!

it is not sustainable and often not effective. typically involve excessive anthelmintic use and promote development of resistance

recipe based is treating all ewes at lambing and all lambs later in season (doing an all at once type thing, and only once)

26
Q

how should you use anthelmintics with good practice?

A
  • use evidence-based approaches, including monitoring parasite burdens and grazing mgmt [minimize # of anthelmintic doses, use FECs to monitor]
  • target anthelmintic tx only to those animals that need it when they need it, aiming to control pasture contamination [minimize # of anhelmintic doses] [use Targeted Selective Treatment, TST]
  • assess drug efficacy and adopt good treatment practices; dose individual or based on heaviest animals (goats usually require higher doses) [perform FEC 2 weeks post tx to check drug efficacy]
  • always use the full therapeutic dose (avoid underdosing!)
  • no evidence that annual rotation of anthelmintic class is useful –> don’t advice
  • prevent bringing resistance onto the farm with new animals
27
Q

what is “in refugia” and why is it important?

A

portion of parasite pop not exposed to drug tx is said to be “in refugia” (parasites in untreated hosts or in external environment)

the larger the in refugia pop, the less selection pressure by drug tx –> reduces drug-resistance pressure = slow down development of resistance

28
Q

explain the concept of targeted selective treatment (TST)

A

treating only animals in a group that are likely to benefit
slows down anthelmintic resistance

29
Q

how do you know when to use anthelmintics when you’re using Targeted Selective Treatments (TST) if Haemonchosis is the main problem?

aka what are the potential markers for indicators for TST?

A

tx on basis of anemia
FAMACHA (tx 4s and 5s, 3s if situation calls for it)
FEC is additional, not the only indicator!!

30
Q

how do you know when to use anthelmintics when you’re using targeted selective treatments (TST) if Teladorsagia or Trichostrongylus is the main problem

AKA what are potential markers for indicators for TST?

A
  • BCS for ewes
  • growth rate for lambs
  • diarrhea assessment (DAG) score
31
Q

when using Targeted Selective Treatments (TST), you should aim for treating no more than ___ of the flock, depending on the situation

A

1/3

32
Q

how do you prevent resistance coming onto your farm when you bring in new animals?

A
  • tx all incoming sheep and hold from pastures for at least 24-48h
  • use an effective drug! best choice depends on source of animals
  • use combos of anthelmintic
  • check FECs 10-14 days later (can also check for coccidia oocysts)
33
Q

what is the difference bt parasite resistance and parasite resilience/tolerance

A

resistance: ability of host to resist infection
resilience: ability of host to tolerate effects of parasite infection

34
Q

what is important to know about Eimeria spp and coccidiosis in sheep and goats?

A
  • large number of species
  • some pathogenic species, some not
  • different parts of GIT
  • highly host specific specific (no cross transmission)
  • disease can occur indoors and outdoors
  • disease mainly occurs from 3 weeks to 3-mo of age
35
Q

what are the C/S of acute coccidiosis?

A

classic presentation

  • abd pain/straining
  • water D+
  • dysentery (blood, mucus, fibrin)
  • pyrexia
  • lack of appetite
  • weakness
  • death
36
Q

what are the C/S of chronic coccidiosis?

A

diagnostic challenge

  • Clinical: chronic d+, poor growth rates, poor condition
  • sub clinical: reduced growth rates, reduced conversion efficiency
37
Q

how do you diagnose coccidiosis?

A

C/S, risk factors, hx of previous outbreaks/problems, necropsy, FEC

38
Q

true or false: Eimeria oocysts are extremely resistant to environment (survive freezing). they last for many months, up to a year

A

true !!

39
Q

what are some factors that increase disease risk to coccidiosis?

A
  • high stocking density
  • poor hygiene
  • moisture
  • stress
  • intercurrent dz
  • poor nutrition
40
Q

true or false: anti-coccidial drugs act at the same part of the Eimera life cycle

A

false! they act at DIFFERENT parts of the life cycle

41
Q

why is it important to know that anti-coccidial drugs act on different parts of the life cycle?

A

because depending on the part of the life cycle they act on, they are good for different things

act on early stages of life cycle:
- only useful for prevention
- don’t allow immunity to develop

act on later stages of life cycle:
- useful for treatment and prevention
- allow immunity to develop

42
Q

which anti-coccidial drug do we have to know? what are its features?

A

Toltrazuril (Baycoz 5%)

targets all intracellular stages
oral suspension
treatment & prevention !

also should know amprolium, but it’s not starred (mainly used for treatment)

43
Q

how do you treat coccidiosis in a flock?

A
  • treat all animals in group, not just those affected –> amprolium in drinking water 5 days, toltrazuril single oral dose
  • remove animals from contaminated environment (reduce stocking density if possible)
  • separate severely sick animals for supportive therapy
44
Q

true or false: prevention is better than curing coccidiosis. why or why not?

A

true!
often long-term damage to gut following clinical episode

45
Q

how do you prevent coccidiosis?

A
  1. use anticoccidials as preventatives
  2. mgmt strategies to prevent coccidiosis
46
Q

how do you use anti-coccidials as preventative to coccidiosis

A
  • decoquinate, monensin, lasalocide –> in feed admin at least 28 d to reduce environmental oocyst contamination
  • toltrazuril –> single oral tx in prepotent period before expected onset of C/S
47
Q

what are mgmt strategies to prevent coccidiosis?

A
  • improve sanitation of facilities, pastures, pens, feeding, water sources
  • avoid moist areas without direct sunlight (ex. under feed bunks, areas near water troughs)
  • avoid crowded pens and pastures
  • implement quarantine period before intro of new animals to herd
  • minimize weaning stress (creep feeding, visual contact b/t ewes and lambs, etc)
  • ensure good nutrition program
  • grazing mgmt!! –> avoid overgrazing, separate grazing of different age groups

sheep/goat class (6 decks)

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