Infertility in sheep and goats Flashcards
How to calculate lambing %
= lambs born/ewes put to tup X 100%
What is the main cause of infertility in sheep
Infectious causes of abortion
What BCS do we want a lowland ewe at weaning, tupping and lambing
Weaning: 2.5
Tupping: 3.5
Birth: 3
How can stress cause abortion
Via causing prostaglandin release
Which drugs cause abortion/parturition at different stages in sheep and goats
Sheep: early pregnancy = PGF2alpha; late pregnancy = corticosteroids
Goats: prostaglandins; because have a CL at all times
(corticosteroids also will in late pregnancy)
Which goat species is get habitual abortions (genetic)
Angora
What is the cause of enzootic abortion of ewes
Chlamydia abortus
Most common two infectious causes of abortion
1) Chlamydia abortus (enzootic abortion of ewes)
2) Toxoplasmosis
Effects of ewes being infected with chlamydia abortus at different stages of pregnancy
Early pregnancy: get abortion in late pregnancy
Late pregnancy OR non-pregnant: dormancy and can reactivate in next pregnancy to cause abortion
How can lambs become infected with C abortus after birth
Via uterine discharge (NOT MILK)
How is most C abortus spread
Sheep to sheep
_ most infections are due to purchase of an infected animal
What stage of gestation do we see abortion due to C abortus
Last 2 weeks
What does an enzootic abortion (C abortus) look like
Fetus normal; may see inflammatry lesions in liver, lung etc
Placentitis and placental necrosis
Stain smears from intercotyledonary areas using ZN stain
How can vaccination against C abortus help reduce abortions and when/what do we treat with
Reduces shedding BUT WILL NOT ELIMINATE INFECTION
should give as close to 95 days gestation as poss
- Long acting oxytetracycline
> Repeat every 2 weeks until lambing
What do we do with ewes that have aborted due to C abortus
Keep them! They will be immune next week
> BUT isolate for 3 weeks and burn dead lambs
If we want to foster lambs onto her; DO NOT KEEP THESE FOR BREEDING; they will most likely get infection
Vaccination protocols for different EAE situatins
In outbreak can vaccinate pregnant ewes with INACTIVE PREPARATION to reduce risk of abortion from previously infected ewes
Temp sensitive prepration should be given every 1 or 2 years in high risk flocks (>5% abortion) and only once in low risk flocks (<5% abortio)
Difference between placenta of abortion from EAE and toxoplasma
EAE: placentitis and necrosis; abnormal intercotyledonary areas
Toxoplasma: cotyledons bright red with small white nodules; intercotyledonary areas NORMAL but oedematous
What stain do we use on cotyledons to identify toxoplasa gondii
Giemsa/Leishman stain
What to do with a ewe that has aborted due to toxoplasma gondii
Probably don’t need to isolate; no lateral spread (it is from environment)
KEEP HER; will be immune next year