Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
61 Cards in this Set
- Front
- Back
|
What are the main causes of infectious abortion in sheep?
|
EAE
Toxoplasmosis Campylobacter Salmonellosis Border Disease Listeriosis |
|
|
What are some examples of non-infectious abortive causes?
|
Pregnancy toxaemia
Poor nutrition Stress Poisoning Drugs |
|
|
What level would suggest infective causes of abortion in a flock?
|
Anything over 2%
|
|
|
What does a 5% abortion rate actually cose the farmer?
|
10% becuase of subsequent lamb loss (undeveloped, stillbirths, weak lambs)
|
|
|
What is the most common cause of infective abortion in ewes?
|
EAE
|
|
|
What is the causal agent of EAE?
|
Chlamydophila abortus
|
|
|
What is special about the lifecycle of C. abortus?
|
Has an infectious extracellular phase (elementary body) and a non-infective intracellular phase (reticulate body)
|
|
|
How much does EAE cost the UK sheep industry every year?
|
50 million pounds
|
|
|
Are ewes affected with EAE?
|
Usually no unless RFM and metritis
|
|
|
When is abortion normally seen with EAE?
|
The last 2-3 weeks of gestation
|
|
|
What is the foetus normally like in EAE?
|
Normall aborted quite fresh. Soemtimes there are stillborn or weakly lambs.
|
|
|
What is the major pathological component of EAE?
|
Placentitis, with changes beginning after 90 days gestation (get thickened IC areas!)
|
|
|
How do ewes get infected with C. abortus?
|
Ingestion or inhalation
|
|
|
How is EAE diagnosed?
|
Confirmed by the demonstration of chlamydial elementary bodies in smears from affected cotyledons. Stain with ZN and will see clusters of red against a blue background. Paired serolgy if foetal products not available.
|
|
|
Is EAE zoonotic?
|
Yes
|
|
|
What is the foetus normally like in EAE?
|
Normall aborted quite fresh. Soemtimes there are stillborn or weakly lambs.
|
|
|
What is the major pathological component of EAE?
|
Placentitis, with changes beginning after 90 days gestation (get thickened IC areas!)
|
|
|
How do ewes get infected with C. abortus?
|
Ingestion or inhalation
|
|
|
How is EAE diagnosed?
|
Confirmed by the demonstration of chlamydial elementary bodies in smears from affected cotyledons. Stain with ZN and will see clusters of red against a blue background. Paired serolgy if foetal products not available.
|
|
|
Is EAE zoonotic?
|
Yes
|
|
|
Can ewes become immune to EAE?
|
No. Ewes which have aborted from EAE will not abort EAE again but some may remain ntestinal carriers and therefore a source of infection.
|
|
|
What should the farmers be told about the following year after EAE shows up?
|
It may be worse bc of infection of susceptible ewes during late pregnancy or when they are not pregnant
|
|
|
How to treat EAE in the face of an outbreak?
|
Long acting Oxytet - two IM injections (20 mg/kg) at a 2 week interval. Commence at first sign of abortion or strategically at 4 and 2 weeks before the expected lambing date
|
|
|
Key points to EAE prevention in clean flocks
|
Maintain closed flock
Never buy orphaned lambs Only purchase replacements from an accredited dealer Isolate aborted ewes Investigate abortions promptly |
|
|
Is there a vaccine for EAE?
|
Yes. It is a live attenuated one called Enzovax and must be completed 4 weeks prior to breeding and vacc ewe lambs as soon as poss after 5 months. One injection for life is fine. It doesnt make a difference for those already infected though.
Also there is Mydiavac, an inactivated vacc given 4 weeks prior and 4 weeks after tupping. It claims to be able to reduce shedding in the face of an outbreak. |
|
|
How would one convince the farmer to start a vacc programme for EAE?
|
Tell him that the cost of Enzovax is 3.50 per dose while 2 inj of Oxytet is the same price!
|
|
|
What is the main causal agent in Toxoplasmosis?
|
Toxoplasma gondii
|
|
|
What is the lifecycle of T. gondii?
|
Asexual cycle with no host specificity and a sexual cycle confined to cats which results in the production of oocysts in cat faeces.
|
|
|
C/S of T. gondii abortion?
|
Abortions, mummifications or still births in the very late stages of pregnancy
|
|
|
Are the ewes affected by T. gondii?
|
No
|
|
|
Can clinically normal lambs be born from a T.gondii infected dam?
|
Yes if the dam was infected very late in gestation - lamb will be a carrier
|
|
|
What is the pathology of T. gondii?
|
Necrotic cotyledons (speckled white necrotic foci)
|
|
|
Difference bt pathology of EAE and T.gondii?
|
IC area normal in T. gondii cases.
|
|
|
How is toxo diagnosed?
|
Serology
FAT on foetal fluids to detect Ab |
|
|
Control of toxo in the face of an outbreak?
|
Not much can be done as the protozoal oocysts are in the feed and beddng. Control the rodent and cat population
|
|
|
Do sheep become immune to T. gondii?
|
Yes
|
|
|
Prevention of toxo?
|
Vaccinated with Toxovax, a live vaccine. One vaccination is enough. As for Enzovax, inject replacements 4 weeks before tupping. Cost is 2.50 per dose.
|
|
|
What are the causes of Salmonellosis abortion?
|
S. typhimurium
S. dublin S. montevideo S. abortus ovis |
|
|
C/S of salmonella abortion?
|
With S. abortus and S. montevideo, abortion occurs in the last 6 weeks and ewes are not sick.
With S. typhimurium and dublin, ewes are pyrexic and scouring and may die. |
|
|
Pathology of salmonella foetus?
|
Tons of autolysis
Rotten lamb smell because of necrosis In bits and pieces |
|
|
How to diagnose salmonella abortion?
|
CS if ewe is sick
G- organisms on direct smears of placenta and stomach contents of foetus Culture bacteria |
|
|
Salmonella zoonotic?
|
YES
|
|
|
What are most salmonella outbreaks due to?
|
Infected feed or water
S. montevideo from wild birds |
|
|
Do ewes become immune to salmonella
|
Yes, rare for it to be endemic
|
|
|
Causal agents for Campylobacter abortion?
|
C fetus subspp fetus (intestinalis)
C jejuni |
|
|
When is abortion seen in Campy cases?
|
Last 6 weeks of preg
|
|
|
Pathology of campy?
|
Placentitis develops 7-25 days after infection
|
|
|
How is campy transmitted?
|
Orally
No venereal spread like in cattle |
|
|
Is campy zoonotic?
|
YES
|
|
|
Diagnosis of campy?
|
ZN stain from smear from cotyledons and sotmach contents - see characteristic small, comma-shaped bacteria
|
|
|
Do sheep dvp immunity to campy?
|
Yes
|
|
|
Is there a vacc for campy?
|
NO
|
|
|
What is the causal agent of Border Disease?
|
A pestivirus related to BVDV in cattle and swine fever in pigs
|
|
|
What are the outcomes for Border Disease depending on the stage of gestation when infected?
|
Early gestation (b4 60 days) will have foetal death and resorption, abortion or still birth. May also have some survival to become "hairy shakers", PI lambs.
Between 60 and 85 days most lambs will have CNS issues or cerebellar hypoplasia After 85 days lambs are normal with detectable Ab levels |
|
|
Ewes affected by border disease?
|
Only a mild disease when seroconverting to the virus
|
|
|
Diagnosis of BD?
|
No prob if hairy shakers are present! FAT staining or virus isolation from blood/tissues.
|
|
|
How is BD transmitted?
|
Direct contact
Perhaps with BVDV in cattle?! |
|
|
Vacc for BD?
|
No
|
|
|
Control of BD?
|
Cull affected lambs and dont retain homebred ewe lambs (PI lambs)
|
|
|
Causal agent of Listeria abortion?
|
L ivanovii
L monocytogenes sensu stricto |
|
|
When do Listeria abortions occur?
|
Any time but usually 3rd trimester and can happen as little as a week after ingestion of listeria silage.
|
