Abortion is the expulsion of recognisable foetuses before day 110 or stationed. The aborted material must be seen for a record to be made, as abortion can be overlooked unless the progress of pregnancy is being carefully monitored. Death of the concept uses may occur from hormonal causes early as four live foetuses are required to maintain an early pregnancy.
- Causes of Abortion >
- Effects of Abortion >
- Diagnosis of Abortion >
- Treatment & Control of Abortion >
Causes of Abortion
After implantation, infection is the main cause of abortion, directly or indirectly through fever as a result of the infection of the fetus. Fever is the cause of abortion in erysipelas. Invasion of the fetus can occur in many viral and bacterial diseases. In some, invasion results in fetal death and resorption of the dead foetuses, and in older pregnancies, the fetus may become Mummified and later, still birth may occur.
All combinations of normal, resorbing, and still born Mummified foetuses may be aborted. Major infections capable of causing abortion are Aujeszky's disease, brucellosis, enterovirus infections, leptospirosis, parvovirus, PRRS, swine fever and toxoplasmosis.
Ingestion of the Fusarium toxin zearalenone is also capable of causing abortion, as are management factors, such as high carbon monoxide concentrations and the use of prostaglandins in too early stationed.
Effects of Abortion
Sows may be seen to abort and the aborted material may be found on the floor of their accommodation. The sow may not appear ill in some cases (enterovirus, parvovirus, leptospirosis some), but in other diseases such as erysipelas, there is clear evidence that the sow is ill, off feed, and has evidence of the disease.
In the case of erysipelas, high fever and the characteristic skin lesions are often found. The vulva of the sow may be blood stained and the tail and perineum (hind quarters) may be smeared with sticky discharge. The products of abortion may be visible as embryos (large sacs 10-20 cm in length, with a central dark area, the embryo itself, from which blood vessels radiate) or as perfectly formed pig foetuses. These have their eyes closed and are hairless. They may be partially secayed, or mummified perfectly with fresh haemorrhages on their skins. Placentas may be absent, although they are sometimes passed surrounding aborted piglets.
As sows frequently eat aborted material, abortion is hardest to detect in loose-housed animals. Where abortion is missed, the termination of pregnancy may be detected only when an animal, previously known to be pregnant, or fails to farrow returns to oestrus.
Diagnosis of Abortion
Abortion may be detected by finding the aborted foetuses or placenta. The sow responsible may be identified by the presence of fever or other signs of disease or abortion on the sections of the tail, vulva or perineum. She may be detected by testing the pregnancy group.
Abortion is recorded in pig herds as a routine. Numbers aborting should be small (less than 1%), but if they reach 2.5%, the cause should be determined. The cause may be identifiable from careful inspection of the animals for the presence of diseases which might cause abortion. The rectal temperature should be tasks to establish the presence of fever.
Management factors should be investigated (poorly adjusted gas heaters, the injudicious use of prostaglandin) and evidence for the presence of zearalenone poisoning sought (enlargement of the vulvas or piglets, enlargement of the mammary glands in non-pregnant gilt).
Evidence for the presence of specific diseases comes from laboratory examination of the aborted foetuses or blood from the affected sow. Virus, Leptospira etc may be isolated from the foetuses or demonstrated in tissues, or antibody may be found in the fluid from the chest of aborted foetuses. Antibody may be present in the blood of the sow.
Treatment & Control of Abortion
The ability to prevent further abortions varies, depending on the cause. For example:
- Zearalenone toxicity can be eliminated rapidly by feeding rations clean.
- Carbon monoxide poisoning can be eliminated by adjusting gas heaters.
- Toxoplasmosis may be prevented by stopping contamination of pig feed by cat faeces.
- Erysipelas can be treated easily with penicillin and tetracyclines with leptospirosis.
Solid immunity follows elimination of these infections. Less specific infections of the uterus can be eliminated, but ideally the animals should be culled as persisting infection may reduce fertility.
To control abortion, sows can be vaccinated against erysipelas (Intervet: Erysorb plus , Vétoquinol, Porcilis Ery, And Colisorb Porcilis Ery + Parvo, Fort Dodge: Suvaxyn Ery, Suvaxyn Parvo / E) And parvovirus (Intervet Porcilis Ery + Parvo, Fort Dodge: Suvaxyn Parvo, Suvaxyn Parvo / E). In some countries, vaccination against leptospirosis (Pfizer, not UK), Aujeszky's disease (Intervet: Porcilis Begonia DF , Fort Dodge: Aujeszky Suvaxyn ), Swine fever and PRRS (Intervet: Porcilis PRRS, Boehringer Ingelheim: Ingelvac PRRS KV ) Is also possible. Vaccination requires at least 14 days to protect against an agent. There are no vaccines for enteroviruses. Brucellosis is notifiable and controlled by other means.
Animals which have aborted should come back into oestrus within 10 days and may then be served. The exception is if body condition has been lost, when consideration should be given to increasing feed and delaying service. Those that do not return to oestrus or do not hold to the next service, should be culled.
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