Parasitology Flashcards

cattle, SR, and equine

1
Q

Which anthelmintic is resistance least common in for equine cyathostomins?

A

macrocyclic lactones

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2
Q

what is targeted selective treatment?

A

it is where you treat ONLY the animals that need to be treated as opposed to treated all of the animals.
Its based on the 70/30 rule (70% animals have 30% of the parasite pop. and only 30% animals have 70% of the parasite pop)

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3
Q

what anthelmintic kills hypobiotic larvae of small strongyles?

A

moxidectin

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4
Q

Are the targeted selective treatment protocols the same for equine, bovine, ovine, etc.?

A

no

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5
Q

what happens when cyathostomins are killed by anthelmintic drugs?

A

hypobiotic larvae repopulate the intestine

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6
Q

what do the major strongylid parsites of ruminants and horses have in common?

A
  1. eggs exit host in manure
  2. eggs dev infective stage in env
  3. anthelmintic resistance is a problem
  4. arrested dev in life cycle
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7
Q

what is fecal egg count used for in food animals? (2)

A
  1. breeding purposes
  2. ID high contaminators
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8
Q

What increases refugia in food animals?

A

targeted selected treatment
selective nontreatment

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9
Q

which 4 things can be used as indicators for targeted selective treatment in food animals?

A
  1. FEC
  2. Milk production
  3. FAMACHA
  4. BCS
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10
Q

what can speed development of anthelmintic resistance? (3 things)

A
  1. pour on products
  2. alternating anthelmintics
  3. long-action products
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11
Q

What is the impact/effects trichostrongyles have on immature cattle (<2y)?

A

clinical disease or subclinical impact on growth and development

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12
Q

What is the impact/effects trichostrongyles have on mature cattle (>2y)?

A

clinical disease is very UNusual.

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13
Q

Why are pour ons and long-acting products so popular?

A

because they are convenient and easier, and the pour ons are even really cheap.

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14
Q

What are the 3 drug groups for treating food animal parasites?

A
  1. macrocyclic lactones (-mectins)
  2. benzimidazoles (-bendazoles)
  3. nicotinics (-antel, -misole)
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15
Q

What is the deworming recommendation for COWS?

A

no routine recommendation – treat depending on circumstances (poor BCS, hx of chronic problems, etc.)

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16
Q

What is the deworming recommendation for spring-born calves?

A

some treat calves at the beginning of grazing season (march/april)
however MIDSUMMER treatment shows best benefit

+/- treatment at weaning (if you are keeping)

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17
Q

why do calves less than 4 months of age not have a high number of worms?

A

they arent grazing as readily

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18
Q

What is the deworming recommendation for fall-born calves?

A

deworm at pasture turnout/start of grazing season in order to limit maturation of larvae that are remaining from the previous season
only retreat them in the fall if they are staying for the next season

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19
Q

What are 3 other situations in which routine deworming treatments are common for food animals?

A
  1. animals entering feedlot
  2. backgrounding
  3. bringing in cattle from multiple sources
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20
Q

What is selective nontreatment?

A

not treating some animals to leave a certain percentage of the herd “untreated” to increase refugia and decrease the speed of resistance

Ex. you have a herd of 500 animals, so you should treat 400 and leave 10-20% untreated (100 animals).

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21
Q

why is targeted selective treatment not common in cattle?

A

it is not feasible to do FEC for a high number of cattle and not accurate since most eggs are from cooperia
and weights do not accurately predict the animals response to the deworming

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22
Q

What is the benefit of combining multiple anthelmintics to treat food animal parasites?

A

additive effect of treatment (kill more, broad spectrum)
when you achieve higher efficacy, there will be fewer resistant survivors (diluting resistant genes)

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23
Q

T/F: in relation to food animal parasite treatment, even when individual drugs showed reduced efficacy, a combination of drugs is effective

A

true

24
Q

T/F: when using combination of drugs to treat food animal parasites, you should use 2 or 3 drugs from different drug groups at the full recommended dose.

A

true

25
Q

What are the 3 components of integrated parasite control for cattle?

A
  1. selective nontreatment + test drug efficacy
  2. pasture management
  3. nutritional analysis
26
Q

T/F: Eimeria causes disease primarily in adult ruminants

A

false – immature
up to 1y in cattle, it causes diarrhea, dehydration, stunted growth, and possibly can be fatal.
it can also cause subclinical loss in wt gain and development

27
Q

How can we control coccidia infections in ruminants?

A
  1. prevent accumulation of oocysts (clean feeders/waters, reduce crowding, clean resting areas)
  2. coccidiostat tx (ionophores, decoquinate, amprolium) where disease is expected (weaning, postweaning, entry into feedlots)
28
Q

Which animals (age) should be put on pasture with the fewest worms to help remove larvae?

A

young animals
animals in early lactation (the offspring not the mom)

29
Q

What is considered the “best way” to manage a pasture to reduce parasite burden?

A

pasture rotation – move trhrough the paddocks in a rotation to allow larvae to die over time in the “resting” pastures
leave ungrazed for 60 days at minimum

30
Q

How does harvesting pasture regrowth for hay speed up removal of larvae from pasture?

A

larvae die when land is plowed up and replanted

31
Q

how often should dewormer efficacy be checked in horses?

A

every 3 yrs by fecal egg count reduction test (FECRT)

32
Q

What is “egg reappearance period”?

A

the length of time it takes cyathostomin eggs to appear after treatment.
ERP reflects maturation of larvae NOT removed by treatment, it does not reflect new infection

33
Q

What is the current deworming recommendation for horses?

A

deworm high SHEDDERS up to 4x/year to remove most of pasture contamination

to identify high shedders by doing 1-2 McMaster fecal exams per year when you expect eggs counts to be highest (high contaminator = >500 epg)

34
Q

T/F: you should perform fecal egg counts in order to establish which animals have clinical parasitism and need to be treated

A

false – FECs do NOT reflect clinical parasitism

FECs give you information about HIGH shedders, in other words, which animals are responsible for contaminating the pasture

35
Q

T/F: young horses (<3yo) are treated as high shedders regardless of egg counts because they have higher susceptibility to all parasits

A

true

36
Q

What timeframe should you deworm horses?

A

right before grazing season

37
Q

Name 6 components of integrated parasite control for horses?

A
  1. reduce exposure to larvae on pasture (limit pasture time)
  2. pasture rotation
  3. mixed/alternate grazing
  4. make hay from pasture regrowth
  5. harrowing/dragging pasture
  6. manure removal
38
Q

what is the best TST strategy for sheep?

A

FAMACHA

39
Q

what is the best parasite evaluation strategy for genetic selection and breeding purposes in small ruminants?

A

FEC

40
Q

why do we use FAMACHA to control barber pole worm?

A

FAMACHA shows us animals that are experiencing anemia most likely due to parasite burden. This will help us identify which animals have more severe disease and need to be treated to control haemonchus contortus.

41
Q

what drug(s) are FDA-approved for clinical coccidiosis in sheep and goats?

A

none are FDA approved!

42
Q

Large numbers of H. contortus cause what features of clinical disease in small ruminaints?

A

anemia, bottle jaw, weakness, and death
decreased gains and growth

43
Q

T/F: in addition to anemia, weakness, and death, H. contortus causes diarrhea especially during grazing season

A

false – other trichostrongyles might, but not barber pole worm

44
Q

T/F: sheep ad goats develop immunity against GI worms but goats or primiparous animals are more susceptible to clinical disease than sheep.

A

true

45
Q

Which small ruminants are MOST immune to parasites?
a. lambs/kids
b. dry, non-preg ewes/does
c. preg ewes/does
d. lactating ewe/does

A

b. dry, non-pregnant ewes/does

46
Q

what was the “old” method for internal parasite control in SR that caused rapid profound drug resistance?

A

animals were treated every 2 weeks in the summer to keep most vulnerable animals alive.

47
Q

What is the goal of integrated parasite management?

A

to keep parasite numbers at a level that does NOT have detrimental health effects.
NOT to eradicate parasites

48
Q

Describe the FAMACHA card and how it helps you determine which animals to treat.

A

card scores are 1-5
1 = red = not anemic
3 = pink = hct of 18-22%, so tx depends on other factors
5 = white = severe anemia, near death

do NOT deworm animals that fall into category #1-2
ALWAYS deworm animals that fall into category #4-5
Category #3 depends on situation (lambs/kids, early lactation, poor BCS, concern for condition)

49
Q

What is a FAMACHA ‘system’?

A

the system entails using cards on ALL animals every 2 weeks during the entire grazing/worm season.

impractical d/t # of animals and requires training

50
Q

What is a treatment that is used for H. contortus in conjunction with or in place of anthelmintics and how does it work?

A

copper oxide wire partciles
causes damage and penetrates the cuticle of H. contortus
do not use too often (avoid Cu toxicity)

51
Q

Since FAMACHA is really only good for identifying H. contortus parasite burdens (via anemia), what are other methods within integrated parasite control that need to be used for small ruminants?

A
  1. no/limited pasture
  2. pasture rotation
  3. taking hay crop or plating and reseeding
  4. mixing or alternate grazing
  5. good nutrition (critical for immunity)
52
Q

T/F: manure pick-up is an effective method of parasite control in small ruminants

A

false

53
Q

T/F: letting goats browse is a form of integrated parasite control in that it reduces their ingestion of strongylids that can only get 4- inches high in pasture

A

true

54
Q

How do you select small ruminants for increased parasite resistance?

A

70/30 rule and FEC
1. select animals that have no/low parasite burdens to reproduce, do not select animals that have a lot of parasites
2. by breed – katahdin, carribbean hair sheep, kiko

55
Q

This fungus is fed to animals, passes through their manure, and consumes nematodes to reduce the # of larvae on pasture

A

Duddingtonia flagrans