Nematodes of sheep

Question 1

Nematodes typically have what kind of life cycle

Answer 1

Direct life cycle

Question 2

Nematodes typically have what requirements for environmental stages

Answer 2

Warm and moist

Question 3

Nematodes typically have what clinical signs

Answer 3

weight loss and diarrhoea

Question 4

Most notable clinical sign of Parasitic Gastroenteritis (PGE)

Answer 4

Reduced weight gain
Reduced feed intake (60-70% of reduced DLWG)

Question 5

Cause of clinical signs of Parasitic Gastroenteritis (PGE)

Answer 5

Both developing larvae and adult GI nematodes can cause damage to the mucosal lining of the GIT, leading to discomfort, anorexia and malabsorption, which can be prolonged if the damage is long term

Question 6

Describe distribution of infection for nematodes in sheep

Answer 6

generally over-dispersed, with only few sheep carrying heavy worm burdens, whilst the majority of sheep carry low numbers of worms

Question 7

Parasitic Gastroenteritis (PGE)- Diagnosis

Answer 7

Reduced growth rate (in absence of other ddx)
Faecal worm egg count
Post mortem examination
FAMACHA

Question 8

What is the name of technique used in faecal worm egg count

Answer 8

McMaster
Dilute faeces then multiply result
Give eggs per gram (epg)

Question 9

Nematodirus species are the exception with eggs that look different, much _________ and ___________than the Trichostrongylids, with _______________inside of them

Answer 9

larger and darker

large brown balls visible inside of them

Question 10

Pro of faecal worm egg count

Answer 10

Predict pasture contamination
Determine pattern of infection on individual farms
Encourage farmer/vet interaction
Fecal Egg Count Reduction Test
Nematodirus battus diagnosis

Question 11

Cons of faecal worm egg count

Answer 11

Cannot speciate Trichostrongyle style eggs
FWEC not representative of burden (except H. contortus)
Not related to lamb performance (resilience vs resistance)

Question 12

Parasitic Gastroenteritis (PGE)- Diagnosis

Answer 12

post mortem examination

Question 13

H. contortus- Treatment

Answer 13

Closantel and Nitroxynil

Question 14

Nematodirus battus- Treatment

Answer 14

Benzimidazoles (BZ)

Question 15

What period of time to administer antihelminthics

Answer 15

Autumn to kill hypobiotic larvae

Question 16

Hypobiosis

Answer 16

Arrested development

Question 17

Species that typically go hypobiosis

Answer 17

HaemonchusandTeladorsagia

Question 18

Why do species go hypobiosis

Answer 18

Under unfavourable conditions, such as autumn in temperate climates like the UK or hot dry conditions in other countries

Question 19

Peri-parturient rise (PPR)

Answer 19

These infections produce more eggs because of the reduction in immune response in late pregnancy and early lactation, more nematodes develop and the rate of egg shedding is increased

Question 20

Outline main ways of reducing pasture contamination by ewes during the peripaturient rise

Answer 20

Supporting the ewes to have a good immune response by good nutrition, breeding replacements from ewes with low FWEC, providing clean grazing for ewes and giving lambing ewes anthelmintic treatments during the period of highest egg shedding.

Question 21

Vaccine for Haemonchus contortus (Barber pole worm)

Answer 21

Barbervax

Question 22

Problem with ‘Dose and move’ protocol in the past

Answer 22

Treat lambs with anthelmintic at the time that they are moved to clean grazing (pasture with low larval contamination). However this promotes resistance development because the resistant ones are the only nematodes that will survive treatment and then be deposited on the clean grazing.

Question 23

GIN that resides in abomasum

Answer 23

Teladorsagia circumcincta the ‘brown stomach worm’
Haemonchus contortus the ‘barber’s pole worm’

Question 24

GIN that resides in small intestine

Answer 24

Trichostrongylus vitrinus ‘black scour worm’
Trichostrongylus colubriformis ‘black scour worm’
Nematodirus battus
Has different epidemiology to other nematodes

Question 25

Clinical sign of Teladorsagia circumcincta (brown stomach worm) and time of year

Answer 25

Scour, loss of appetite and weight
Summer

Question 26

Clinical sign of Trichostrongylus species (black scour worm) and time of year

Answer 26

Dark scour, anorexia, poor skeletal growth, chronic ill thrift
Late summer, autumn and/or winter

Question 27

Does Haemonchus contortus cause diarrhoea

Answer 27

No

Question 28

Outline how Nematodirus battus has a different epidaemiology

Answer 28

development of its environmental stages progresses more slowly (taking several months) and mostly occurs while contained within the egg. Once the larvae have reached L2, they are able to hatch and moult immediately to the infective L3,

Question 29

Nematodirus battus- Treatment

Answer 29

Benzimidazoles