Abortion in Sheep

Question 1

What does fat lamb production depend upon?

Answer 1

• Maximal conception rate.
• Minimal embryonic and foetal losses.
• Maximal neonatal lamb survival.
• Minimal losses from other causes.

Question 2

Factors affecting ewe conception rate.

Answer 2

Nutrition of ewe.
- Early feeding (determines early growth and body size).
- BCS at tupping.
- Plane of nutrition prior to tupping.
- Trace element status.
Age and genotype of ewe.
Disease (either direct effect or causes reduction in BCS).

Question 3

What is ram fertility influenced by?

Answer 3

Nutrition and BCS.
Age and genotype.
Disease.
Ram : ewe ratio.
Season (and out of season breeding for early lamb crop).
Weather.
Stress.

Question 4

What causes infertility involving whole groups of rams?

Answer 4

Balanoprosthitis/vulvovaginitis.
Epididymitis and orchitis.
Orf.
Scrotal mange (increase scrotal temp.) (Chorioptes bovis). – must use topical.

Question 5

Need to know about rams before can assess fit to breed?

Answer 5

Males influence by photoperiod.
Libido diminished by pain/disease.
CE.
Check general health and conformation.
Check for lameness.
Check for brisket sores.

Question 6

CE for ram breeding?

Answer 6

Testis – number, size, asymmetry, lumps, scar tissue.
Epididymis – presence of epididymis and check for epididymitis.
Penis – injury, urethral fistulae, appendage, spiral deviation.
Prepuce – Trauma (shearing) infection.

Question 7

Ram semen collection and examination.

Answer 7

• Electro-ejaculator (can only be used by a vet and may need to sedate ram).
• Vagina of a served ewe.
• Artificial vagina (AV) best option….need a ewe in oestrus.

Question 8

Ewe to ram ratios.
1. ram lambs.
2. mature rams.
3, synchronised ewes.

Answer 8

1. 1:25 for ram lambs.
2. 1:40 for mature rams.
3. 1:10 for synchronised ewes.

Question 9

Main cause of embryonic and foetal losses?

Answer 9

Infectious abortion. Most zoonotic.

Question 10

Immediate action for suspect infectious abortion.

Answer 10

• Isolate (at least until discharges dry up – 7-20d):
  – ewes that have aborted.
  – ewes that have a vaginal discharge.
  – ewes w/ very sick/weak lambs.
• Mark these ewes for easy ID!
• Retain for testing:
  – Any foetal membranes.
  – Dead foetuses.
  – Dead lambs.

Question 11

1. What to look at on the foetal membranes when examining them?
2. Appearance of placenta of ewe w/ chlamydophila.
3. Appearance of placenta of ewe w/ toxoplasma?

Answer 11

1. • Cotyledons.
     - Intercotyledonary space.
2. V thickened placenta.
3. White and lobulated cotyledons.

Question 12

1. PM of foetus w/ Campylobacter foetus?
2. What is no foetal membranes for sample and exam?

Answer 12

1. Look for characteristic liver lesions and occasionally enlarged abomasum.
2. • Take paired serology from ewes.
     – Chlamydophila –> ELISA.
     – Toxoplasma –> LAT.

Question 13

What is the clinical picture when infectious abortions suspected?

Answer 13

• Were there any abortions last lambing?
• Is the flock closed?
• When is abortion occurring? Early/late gestation.
• Mummified lambs?
• What do any surviving lambs look like?
• Ewes showing clinical signs?
• Any other clinical signs in animals that have aborted or w/in the flock?:
  – Enteritis (Salmonella).
  – Encephalitis (Listeria).
  – Septicaemia (Salmonella, Listeria).

Question 14

1. What happens when aborted lamb sent to lab?
2. What happens when placenta sent to lab?
3. What happens when maternal blood sent to lab?

Answer 14

1. Liver culture.
   Foetal fluid (serology for toxin).
   Brain (histopathology).
2. Smear (for Chlamydophila or other bacteria.
   Culture for bacteria.
3. Check for Chlamydophila.
   Check for Toxoplasma.
   Check for Border disease.
   Check for Q fever.

Question 15

What to do while wating for Dx?

Answer 15

• Supervise foetal material disposal.
• Advise on hygiene procedures.
• Collect all FMs.
• Use disinfectants.
• Use lots of fresh bedding in pens.

Question 16

What to warn the famer about re zoonosis.

Answer 16

• Nearly all causes of ovine abortion are zoonotic
• Until you get a Dx, you don’t know.
• Be cautious.
• Advise farmer of risks and hygiene measures that may be necessary.
• Pregnant women (incl. vets) should not assist w/ ovine parturition.
• Danger of people handling contaminated clothing etc.

Question 17

1. % abortion considered normal in UK?
2. % material submitted getting a confirmed diagnosis?

Answer 17

1. 2%.
2. 50%.

Question 18

1. List main causes in abortion from most to least regarding their incidence.

Answer 18

• Chlamydophila abortus.
• Toxoplasma gondii.
• Campylobacter spp.
• Other e.g. Leptospirosis.
• Listeria monocytogenes.
• Salmonella serotypes.
  *all zoonotic.

Question 19

1. Financial cost of ovine abortion.
   – cause of losses?
2. Other names to refer to Chlamydial abortion.

Answer 19

1. £30M pa.
   – Loss of lambs.
   – Feeding unproductive ewes for a year.
2. Ovine Enzootic Abortion (OEA).
   Enzootic Abortion of Ewes (EAE).
   Chlamydophila abortus.

Question 20

1. Chlamydophila abortus distribution.
2. Nature and actions of Chlamydophila bacteria.

Answer 20

1. Worldwide. Not reported in Australia or New Zealand.
2. Specialised, intracellular (reticulate body).
   Ruptures cell.
   Then an extracellular infectious phase (elementary body).

Question 21

Clinical signs of Chlamydophila?

Answer 21

• Up to 35% flock abort in 1st year.
• 5-10% abortion in subsequent years.
• Rarely see any ill effects in ewes.
• Abortion approx. 2-3wks before term (late).
• Premature/weak lambs.
• Live lambs which survive.
• V rarely retained placenta.
• Vaginal discharge after abortion.

Question 22

Pathology of Chlamydophila.

Answer 22

Chlamydial growth in placenta from 90d.
Disruption in placental production of progesterone.
- Premature labour.
Lesions seen grossly mainly in intercotyledonary space.

Question 23

1. Chlamydophila epidemiology and transmission.
2. Appearance of Chlamydophila uterine discharge.

Answer 23

1. • Infected foetal membranes = source of elementary bodies.
     - Copious uterine discharges.
     - New born lambs wet w/ foetal fluids (until dry).
     - Intestinal carriers in disease.
     - Do ewes subsequently excrete chlamydia during oestrus?
2. Salmon-pink necrotic discharge.

Question 24

What is meant by Chlamydophila being a latent infection?

Answer 24

Any animal infected (lambs, non-pregnant ewes, ewes in late pregnancy) is expected to abort in next pregnancy.

Question 25

Control and prevention of Chlamydophila?

Answer 25

- Isolate ewes that have aborted/had weak lambs. - Destroy dead foetuses, dead lambs. - Collect placentas and destroy. - Disinfectant lambing pens. - Keep closed flock. - Buy replacement ewes from Chlamydophila free flocks.

Question 26

Use of ABX in face of an outbreak of Chlamydophila?

Answer 26

Long-acting oxytetracycline 20mg/kg IM. Repeated at 10-14d intervals. Suppression of Chlamydial multiplication extends duration of threatened pregnancies. *trying to steer away from this now.

Question 27

Vaccination against Chlamydophila.

Answer 27

Inmeva: inactivated vaccine. - Inactive. - Can use in pregnancy in face of outbreak. Enzovax/Cevac Chlamydia. - Live vaccine. - Cannot use in pregnancy. Low risk flocks have vaccine once only. High risk flocks boosted in 2-3yrs time. Give before tupping to replacement ewes. Can give to bought-in ewes where not sure of Chlamydophila status (won't stop abortion or latent infection but reduces shedding).

Question 28

Decisions to keep or cull when dealing w/ Chlamydophila.

Answer 28

If infected for some year -- keep ewes that have aborted as now immune. If flock newly infected -- cull aborted ewes as there is a carriage risk.

Question 29

Chlamydophila as zoonosis.

Answer 29

Can colonise human placenta. Can cause human abortion (miscarriage). Stillbirth. Maternal deaths have been reported. Pregnant women shouldn't work w/ sheep at lambing time. Danger of contaminated clothing: pregnant person should not handle farmer's clothing for washing. Caution w/ live vaccine. Use rectal gloves for lambings unless sure not pregnant. Normal hygiene measures. No evidence for latent infection in humans.

Question 30

Are other infectious agents that cause abortion classed as latent infections?

Answer 30

No, If they contract infection when not pregnant, they do not abort when they do eventually get pregnant. May develop a temperature at time of infection. Can then develop immunity. If they contract the infection while pregnant, likely to abort this pregnancy.

Question 31

Asexual Toxoplasma cycle.

Answer 31

Ingestion by cat >> gut infection in cat >> oocysts in cat faeces >> ingestion by sheep >> tachyzoites >> bradyzoites in sheep tissue cysts (eaten by cat and cycle repeats).

Question 32

1. How many oocysts in 1g cat faeces? 2. How much cat faeces in 10t of sheep feed? 3. number of oocysts/kg of feed? 4. How many oocysts will infect 1 ewe? 5. How many infective doses per kg feed?

Answer 32

1. 1M oocysts in 1g cat faeces. 2. 50g cat faeces in 10t feed. 3. 5000 oocysts/kg feed. 4. 200 oocysts will infect 1 ewe. 5. 25 infective doses per 1kg feed.

Question 33

1. Clinical signs of Toxoplasma gondii? 2. Appearance of tissue infected w/ Toxoplasma gondii?

Answer 33

1. Early infection = resorption. Mid gestation infection = abortion/stillbirth often accompanied by mummified foetus. 2. White foci visible on cotyledons. Presence of mummified foetus.

Question 34

Treatment and control of Toxoplasma gondii.

Answer 34

Chemoprophylaxis: - Decoquinate 2mg/kg in feed from mid pregnancy. - Monensin (withdrawn due to problems with toxicity). Treatment: - Pyrimethamine and sulfadimidine been used successfully. Vaccination: - Toxovax. -- live attenuated S48 strain of T. gondii. -- Good protection w/ one injection. -- Do not use in pregnant sheep. -- Care w/ self-injection. - Young and old/ill cats excrete most oocysts so ctrl breeding and vermin. - Remove dead lambs and placentae to deny access to cats.

Question 35

Toxoplasmosis as a zoonotic disease.

Answer 35

- Infection during pregnancy can lead to severe foetal abnormalities: hydrocephalis. - 1-6 per 1000 pregnancies affected. - Can also get disease if immunosuppressed. - Can be contracted from oocysts in the environment e.g. flower beds, litter trays, veg plots. - Oocysts in hay, bedding, bulk grain stores. - Undercooked meat (bradyzoites). - Live vaccine by accidental self-injection.

Question 36

1. Where does Neospora caninum sexual life cycle take place? 2. Natural Neospora infections in sheep?

Answer 36

1. Dog. 2. No, only experimental.