Small Ruminant Parisitology

Question 1

Name 3 anti-parasitic drugs licensed for sheep in canada

Answer 1

Ivermectin
Lasalocid
Sulphamethazine

Question 2

Off-label anti-parasitic drugs

Answer 2

Fenbendazole • Decoquinate • Albendazole • (Monensin)

Question 3

Diarrhea

Answer 3

A. Coccidiosis

B. Parasitic gastroenteritis

Question 4

Pathogenic species in sheep (2)

Answer 4

2 pathogenic – E. crandallis, E. ovinoidalis

Question 5

Pathogenic species in goats (many)

Answer 5

E. ninakohlyakimovae, E. caprina, E. arloingi, etc

Question 6

Signalment for coccidiosis in sheep/goats

Clinical signs

Answer 6

very common
• typically lambs/kids @ 1-4 months of age
• usually poor growth, often pasty/diarrheic feces, dullness, abdominal pain, occasionally bloody diarrhea
• pot bellied, open fleeced
• subclinical infections → production impact
• often other diseases (e.g. pneumonia, urolithiasis)

Question 7

Diagnosis for coccidiosis in sheep/goats

Answer 7

Clinical signs + fecal flotation – speciate ?

Question 8

coccidia oocysts in the environment - how do they get there?

Answer 8

(a) oocysts may overwinter in environment
(b) ewes shed small #s oocysts in periparturient period
→ subclinical infections in early lambs → ?
• intensification ↑ likelihood of clinical coccidiosis
outdoors + indoors
• stress → disease (e.g. dietary change, weaning, shipping)

Question 9

Treatment for coccidia

Answer 9

Treatment – isolate clinically affected – fluid therapy?

- treat entire group with coccidiocide (sulfa, amprolium) - move to clean bedding/grazing

Question 10

Coccidia prevention

Answer 10

• good hygiene in barns – clean bedding, dry, feed off ground
• house/graze late lambs in different areas from early lambs
• coccidiostat in lamb creep feed until 90 days old or until market - lasalocid, decoquinate, monensin (!)
- correct dose ?
• if no creep feed – script decoquinate or lasalocid into mineral/salt mix
• coccidiostat to ewes for 30 days prepartum ? - lasalocid, decoquinate

Question 11

3 most important gastrointestinal nematodes (all live in the abomasum). Which cause diarrhea

Answer 11

Teladorsagia (similar to ostertagia)
Trhichostrongylus
Haemonchus (largest) - no diarrhea

Question 12

What causes sudden death?

Answer 12

Haemonchus

Fasciolosis

Question 13

Haemonchus

Answer 13

Sheep + goats – Haemonchus contortus (barber pole worm) Acute disease – sudden death, severe anemia
- lethargy, no diarrhea
Chronic disease – edema, weight loss, poor growth, anemia
Highest pasture L3 levels - late summer (July/August) Losses - lambs, yearlings (+/- adult sheep)

Question 14

Haemonchus - Diagnosis & PM

Answer 14

Diagnosis – anemia, hypoproteinemia,
- often high gastro-intestinal nematode (GIN) egg counts
PM – hyperemic abomasal mucosa + parasite #s 1 parasite = 50μl blood loss/day

Question 15

What is the immunity status of ewes w.r.t. gastroenteritis? lambs?

Answer 15

ewes = significant source of pasture contamination in spring (“peri-parturient relaxation of immunity”: 2-4 weeks before
lambing to 4-8 weeks after lambing)
primarily lambs mid summer onwards (+/- older animals)

Question 16

What are the concerns with parasitic gastroenteritis w.r.t. drug resistance

Answer 16

globally – drug resistance in Teladorsagia and

Haemonchus = major concern:

Question 17

Main things to remember

Answer 17

• ewes = primary source of pasture contamination in spring • prepatent period for important parasites = 3 weeks

Question 18

Goals of drug programs

Answer 18

• minimize drug use
• minimize pasture contamination to end of June (“Targeted
deworming”)
• ideally, only treat animals that require treatment (reduces risk of selection for drug resistance)

Question 19

Seasonal drug protocol for GI parasites

Answer 19

Autumn: Winter:
Deworm at housing with drug that kills adults & larvae
Winter: Sheep overwinter with few larvae and adults
Spring: On pasture, sheep eat infective L3. From infection to egg laying takes 21 days
Summer: Worming prevents pasture
contamination. Naive lambs produce most eggs so must be dewormed!

Question 20

Targetted GI parasite treatment

Answer 20

• Treat ewes at lambing if not treated in fall
• Monitor 4+ weeks after turnout
LSSC Ltd
• Monitor lambs at 4+ weeks after turnout and treat accordingly (if not possible, treat at 4 weeks and 8 weeks after turnout)
If control periparturient rise in ewe egg output – not usually necessary to dose lambs until weaning
• Treat in fall, at housing
MONITOR LAMBS IN JULY

Question 21

What is the famacha guide?

Answer 21

Looks for anemia by looking at the eyes and only treating those with red conjunctiva. It is only applicable in areas with only haemonchus (useful in the south)

Question 22

What type of lice is common in sheep?

Answer 22

Sheep - biting lice (damalina ovis)

Question 23

What type of lice is common in goats?

Answer 23

Damalina caprae

Linognathus stenopsis

Question 24

Clinical signs for lice

Answer 24

winter months
signs = pruritis, wool loss, decrease in weight, (anemia)
more severe if debilitated (malnutrition, GI parasitism)
Trasminitted through direct contact

Question 25

Treatment for lice

Answer 25

Permetrhin, carbaryl
2 treatments 10-14 days apart if non-residual
injectable ivermectin (only for sucking lice)

Question 26

Control for lice

Answer 26

shearing
preventative ttreatment in the fall
drug resistance - change drug class
quarentine treatment

Question 27

Melophagus ovinus is what?

Answer 27

sheep ked

Question 28

Melophagus ovinus is found when? life cycle is where/how long? tramsnission? what does it look like?

Answer 28

• winter months, poor condition
• entire 6-week life cycle on sheep/goats • transmission – direct contact
• pruritus, stained wool → fleece damage, anemia, odour, ↓ value
• shearing – removes larvae + pupae
hot climate – kills keds (remain ventral neck, breech)

Question 29

Treatment for kieds

Answer 29

as for lice - shearing, permethrin, carbaryl, injectable ivermectin

Question 30

Most common mange in cows & sheep?

Answer 30

chorioptic (tail head for cows, feet/scrotum for sheep)

Question 31

Clinical signs for chorioptic mange? Peak season?

Answer 31

Alopecia, erythema, crusts, pruritis - wooless areas

• sheep scrotum, distal limbs
• goats - lower limbs, abdomen, hindquarters
• restless, chew on feet
• temporary infertility in rams?
• chorioptes ovis - host specific, peak in winter months.

Question 32

Chorioptic mange - transmission?

Answer 32

Transmission - direct contact
live off host for a few days
Life cycle = 2-3 weeks
Diagnosis: skin scrapings at the edge of the lesions
Treatment: permetrhin pour on , repeat 10 days (ivermectin doesn’t work well)
Note psoroptic manage is very uncommon in Canada & notifiable

Question 33

What is the nasal bot?

Answer 33

Oestrus ovis (nasal myiasis)

Question 34

How do sheep get infected by nasal bots

Answer 34

fly deposits larvae around/in nostrils in fluid → dorsal turbinates, sinuses (weeks – months) → pupate in ground (in spring)
• initial infestation → no signs
• subsequent infections → hypersensitivity
Clinical signs:
• fly → head shaking, nose rubbing, feet stomping
• larvae → rhinitis, sneezing, mucopurulent nasal discharge • production losses ?
Goats – usually milder clinical signs than sheep - usually with infected sheep
Diagnosis – nasal discharge – numerous eosinophils + mast cells
- season

Question 35

Treatment for nasal bots (oestrus ovis)

Answer 35

IVermectin SC or PO

WInter treatment will kill over-wintering larvae