Small Ruminant PGE Flashcards
Which species primarily cause PGE in this group and which superfamily do they belong to? Also state where they infect.
Trichostrongyloidea
Abomasum - Ostertagia & Haemonchus
SI - Trichostongylus & Nematodirus
What is the other name given to Ostertagia found in sheep?
Teladorsagia
What is the difference between type 1 and type 2 ostertagiosis?
- Lambs during their first grazing season (July-September)
2. After 1st grazing season (January-May)
What is the difference in clinical signs?
In type 2 the lambs have intermittent diarrohea as WAVES of overwintered larvae being to cause disease.
Why does the faecal egg count of Ostertagia increase significantly in a ewe who has just lambed?
Mainly due to the peri-parturent relaxation in immunity but also due to poor nutrition and lack of antigenic stimulation when housed over winter.
How does the source of eggs differ if infection stems from clean or contaminated pasture?
Clean - just the ewes that are the main source of infection.
Contaminated - ewes and lambs as lambs eat infected grass.
What is the particular species that causes Nematodirosis?
N. battus
What is a classic clinical sign of this disease seen in the field?
Lambs huddled round a water trough as they are rapidly dehydrated by the disease.
How can N. batus eggs be recognised?
They are large and have a brownish hue with flattened sides.
When does hatching of L3 larvae from these eggs occur?
After a prolonged period of chill followed by a mean day/nigh temp of > 10 degrees. Eggs can survive up to 2 years but generally hatch after 12 months.
Why do ewes not play a significant role in the epidemiology of this disease?
They do not pass many eggs even during the PPRI.
What appearance does Haemonchus contortus have?
A “barber’s pole” appearance.
Why is the ewe the significant source of infection?
Very few L3 can survive on pasture over winter.
How many cycles of infection are there annually and why?
One. Most ingested larvae become arrested L4 in the abomasal wall.
Outline why a farmer needs to be careful when rearing both sheep and goats.
Goats metabolise anthelmintics faster than sheep, mount a reduced immune response to gastrointestinal worms and are generally more susceptible to these types of worm. Therefore sheep should not be grazed where goats have been previously grazed. Zero grazing is recommended for goats.
