Abortion in Angora goats

Friday, 16th March 2018

Updated August 2020

 

ABORTION IN ANGORA GOATS

How can I know if the Angora kid was premature, aborted or died after birth?

A couple of simple things you can do on the farm to determine when the kid died.

  1. Open up the dead kid and check the lungs.

Kids that have never breathed will have consolidated lungs compared to kids that have breathed.

Simply cut a piece of lung and place it in water. If it floats the kid died after birth. If it sinks the kid was born dead (see the difference in the photo).

abortions_1.jpg

 

  1. If the goat was born alive was there a mis-mothering problem?

Open the abomasum, ‘melkpens’ (this is the part of the stomach that joins the intestine)

You can quickly see if the kid ever suckled by checking the abomasum for milk content.

In kids that never suckled the abomasum will be filled with amniotic fluid which it swallowed while in the uterus and no curdled milk will be seen (see photo below)

abortions_2.jpg

 

  1. Weigh the dead kid

Research has proved the relationship between the weight of the kid and its chances of survival.

  • kids below 2.0 kg only had a survival rate of 50%
  • Kids above 3.5kg had a survival rate of 90%.

abortions_3.jpg

 

It is also important to remember the impact of age of the ewe (dam) on birth weight of the kid. (Research by Gretha Snyman)

abortions_4.jpg

 

The most common cause of premature or late abortion kids is due.

  • Lack of ewe nutrition during the last 6 weeks of gestation
  • Some stressful episode such as handling (usually abort the week after)
  • Change in diet or moved to pasture resulting in ‘starvation in the midst of plenty’. This is due to the adaption period of the rumen which may take 7-10 days.

 

 

Why do Angora goats abort more easily than sheep during nutritional stress?

In a ewe which is energy deficient there is a decrease in blood glucose level which is passed on to the foetus.  This triggers a stress-response by the foetus, causing a rise in cortisol (steroid) production.  As these steroids are oestrogen precursors, this has the ultimate effect of increasing oestrogen production. 

This causes the regression and eventual destruction of the Corpus Luteum (CL), the area of the ovary responsible for progesterone production.

 In Angora goats the CL is the only source of progesterone and is solely responsible for maintaining pregnancy, whereas in sheep, progesterone is also produced by the placenta. For this reason, sheep are significantly less likely to abort during energy shortages.

The aborted foetus is usually well formed, normal in appearance and sometimes still alive when aborted. When energy is supplemented appropriately, abortions will typically stop within two weeks.

POTENTIAL CAUSES OF ABORTION

  • NUTRITION

Probably the most important cause of abortion after day 90 of pregnancy is a nutritional energy deficiency.

Most losses occur in the period just before birth until seven days after birth. Nearly 80% of these mortalities are related to the nutrition of the ewe during the last weeks before kidding.

Trials were performed to determine blood glucose concentration in 20 pregnant ewes receiving a high and low plane of nutrition during the fourth month of gestation (Wentzel, Le Roux and Botha). They concluded a drop in blood glucose levels due to nutritional stress to be the trigger for the onset of hormonal changes related to abortion in Angora goat ewes. In addition, the stress of sub-nutrition during the experimental period increased the incidence of perinatal mortality.

The aborted foetus is usually well formed, normal in appearance and sometimes still alive when aborted. When energy is supplemented appropriately, abortions will typically stop within two weeks.

It is important that care should be taken when:

  • Ewes are moved to a new type of grazing during this time (e.g. to cultivated pastures or lucerne lands). When such a move takes place the ewe takes time to adapt to the altered diet, and the temporary deficiency created by this can lead to abortions even in the midst of plenty. During such a movement an energy supplement should be supplied, or lucerne hay provided a week before the move until several days after introduction to the lands
  • During cold snaps it is important to remember cold stress also increases glucose consumption by up to 66% which is aggravated by restricted grazing at times when goats are housed in sheds. Abortions typically then occur 1-5 days later. Pregnant ewes should therefore when possible be given supplementary feeding when housed.

 

  • Energy deficiencies can occur during handling, kraaling such as at times of crutching, shearing, vaccinating or dosing.

Mineral and Vitamin deficiencies will not commonly cause abortions in late pregnancy but as it can be a factor hence the advice is to supplement the ewes 4-6 weeks before kidding at the time of vaccination.   

  • Vitamin A is essential in production of progesterone so deficiencies result can result in abortion and the reason we advise supplementation 6 weeks before kidding.
  • Manganese (Mn) normally developed but still born kids and skeletal abnormalities may occur. High dietary intakes of Ca such as contained in lucerne reduce Mn absorption.

 

Historically Habitual abortion was a significant factor but through selection has largely been excluded. Habitual abortion (caused by chronic over activity of the ewe’s adrenal cortex) is closely associated with stress abortion, which is usually due to feed disturbance, causing blood sugar levels to drop.

In feed-stress abortions, apparently normal, well-developed kids are expelled after the 90th day of pregnancy. Abortion due to the doe’s overactive adrenal cortex shows signs of oedema (unnatural collection of fluid) in the foetus.

WHAT POTENTIAL INFECTIOUS CAUSES CAN BE CONSIDERED? 

There are not a lot of common infectious causes of abortion in Angora goats in South Africa but a fair number of potential causes that have very rarely or never been diagnosed.

  1. ENZOOTIC ABORTION

Enzootic abortion (Chlamydophila abortus) is potentially the most common contagious disease in Angora goats causing abortion although this needs to be validated. Flocks infected for the first time may have up to 70% abortions. These can occur as early as 3 months into pregnancy where the foetus may be resorbed instead of being expelled. After the initial abortion ‘outbreak’ abortions may then be as low as 5% in the flock and often go undetected.

Small weak kids may be born that die soon after birth. Kids can survive and carry the disease. It is unlikely that the same ewe will abort again due to Chlamydia  and hence the reason why that after the initial outbreak abortions are then often  seen in maiden ewes on a contaminated farm.

 https://www.angoras.co.za/page/abortion-enzootic-abortion#144

 

2. Brucellosis

Brucellosis in Angora goats is caused by Brucella melitensus. This is to date an extremely rare condition in Angora goats and only a few isolated cases have ever been diagnosed in goats South Africa.

https://www.angoras.co.za/page/abortion-brucellosis-melitensis#145

 

3. Rift Valley (RVF)

During a RVF outbreak up to 100% ewes may abort and between 10-100% of kids under 10 days old may die. Kid deaths occur within 12 hours after the fever reaction starts, others may survive longer and die within 12-24. https://www.angoras.co.za/page/rift_valley_fever#33

 

4. Wesselsbron Disease

Wesselsbron disease is usually associated with Rift Valley Fever (RVF) as the conditions and vectors (mosquitos) are similar. New-born Angora kids are most susceptible and deaths are seen whereas in adult goats cases are usually subclinical, although abortions may occur. https://www.angoras.co.za/article/wesselsbron-disease

 

5. Q-Fever (Coxiella burnetii)

Q - fever, Coxiella burnetii, in Angora goats can potentially be associated with abortions and peri-natal deaths although the incidence is unknown and more research is required. The role of Q-fever in abortions is also uncertain as antibodies have been detected in goats aborting as well as those not aborting.

https://www.angoras.co.za/article/q-fevercoxiella-burnetii#230

 

6. Campylobacter

 Campylobacter (Campylobacter fetus fetus) is NOT a current reproductive issue in Angora goats but is a major problem effecting fertility in cattle in South Africa (Campylobacter fetus venerealis). Also referred to as ‘Vibriosis’ in the past. It can cause abortion during the last 6 weeks of pregnancy but can result in early neonatal loss. https://www.angoras.co.za/article/campylobacter#270

 

7. Listeriosis

Listeriosis has not been diagnosed in Angora goats in the Karoo and is not economically important. It potentially, but rarely, effects most farm animals as well as humans. Listeriosis is caused by a bacterium Listeria monocytogenes and can cause abortion. https://www.angoras.co.za/article/listeriosis#255

 

8. Hairy Shaker, Border disease

Border disease (Britain) or hairy shaker disease (Australia and New Zealand) is a congenital disorder of lambs characterized by low birth weight and viability, poor conformation, tremor, and an excessively hairy birth coat. Goat kids may also be affected. https://www.angoras.co.za/article/hairy-shaker-disease-border-disease#271

 

9. Leptospirosis

Leptospirosis has not been diagnosed in Angora goats in South Africa.

The dry and hot conditions in the Karroo are very unfavorable to leptospirosis. Leptospirosis in South Africa has mostly been reported from areas with relatively high rainfall such as Mpumalanga, KwaZulu Natal and the coastal area of the Eastern Cape provinces. https://www.angoras.co.za/article/leptospirosis#272

 

10. Toxoplasmosis

The cause of abortion in Angora goats in South Africa was extensively investigated by Malherbe and Van Heerded in the 1950’s and Toxoplasmosis was discarded as a potential cause of Abortions in Angora goats in South Africa. It potentially could be a cause where goats and cats may be in close proximity. Toxoplasma has been diagnosed as a cause of abortions in Angora goats in Europe.

 https://www.angoras.co.za/article/toxoplasmosis#274

 

Other potential non-infectious causes of abortion may include:

 

  1. Live vaccines

The use of ‘live’ vaccines such as RVF or Enzootic abortion must not be given to pregnant ewes as this may cause abortions and congenital abnormalities

 

  1. Lucerne and oestrogen containing pastures

Lucerne may contain phytoestrogens which in theory can lower Angora goat conception/fertility. Studies in Israel, North America, Europe, New Zealand and Australia have confirmed that coumestans in cause a loss of reproductive efficiency in herbivores. In studies where lambing (sheep) was compared for lucerne and a phytoestrogen-free treatment, the mean decrease in lambs born/ewe was 13% due to decreased ovulation rather than abortion.

Due to the increased estrogen in theory could potentially affect the levels of progesterone (hormone of pregnancy) https://www.angoras.co.za/page/mating_on_lucerne_lands_can_reduce_fertility

 

Dr Mackie Hobson

© SA Mohair Growers - 2020 | Links | Abortion in Angora goats

Website Design and Search Engine Optimisation (SEO) by ZAWebs Designs | Web Hosting by ZAWebs Hosting