Dear Daktari
I am a dairy farmer based in Naromoru. I have three Friesian crosses that have been the source of my livelihood. One of them gave birth to a dead and premature calf in January. I have always been very careful when handling my cows, and their health is always my priority. What could have caused the premature birth?
[John Njoroge, Naromoru]
Your cow may have gone through abortion or stillbirth. Abortion is the expulsion from the uterus of a living foetus before it attains maturity or expulsion of a dead foetus of recognisable size at any stage of pregnancy. Abortion occurs between 42 and 260 days during pregnancy. A pregnancy lost before 42 days is not abortion but embryonic death. When it occurs past 260 days, then it is termed a stillbirth. Abortions are either caused by diseases (infectious causes) or non-infectious conditions.
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Non-Infectious Causes of Abortion
Genetic abnormalities
Malformation during foetal growth may result in abortion. Even abnormalities in the internal organs of the foetus will cause the death of the foetus and subsequently an abortion. The abnormal growth of a foetus can also cause an abortion.
Nutritional Causes
Lack of Vitamins A and E, selenium and iron have been shown to cause abortion. This is common in herds where animals are not given adequate mineral supplements.
Heat stress
Heat stress, apart from causing misconception, can also result in abortions. A sudden increase in environmental temperatures may cause abortion. During infections, the resultant fever can cause abortion.
Toxic agents
Poisonous substances when eaten by a pregnant animal can result in abortions and embryonic death. Nitrates, which are found in many plants during dry seasons, can sometimes be toxic. Aflatoxins also cause abortion.
Infectious causes of abortions
Infectious bacterial diseases like brucellosis, Leptospirosis, genital trichomoniasis, listeriosis and Bovine Viral Diarrhea Virus can result in abortion. Most of these diseases are spread during mating.
Bovine Viral Diarrhea is a viral infection that can occur before insemination or during the first 40 days of pregnancy. It causes infertility or embryonic deaths.
Leptospirosis is a zoonotic disease spread through urine and milk from infected animals. This disease is treatable with timely and appropriate treatment.
Brucellosis causes abortion in the second half of pregnancy. It is a zoonotic disease that can be spread to humans. Trichomoniasis is a venereal disease that causes infertility and may cause abortion in the first half of pregnancy.
These are just a few of the infections that may result in abortion. Prevention of abortion in livestock is therefore through proper nutrition. Farmers must always provide gestating animals with required minerals, especially Vitamin A, E, and selenium. Venereal diseases that cause abortion are prevented by the use of Artificial Insemination. Utmost care must be taken when handling aborted foetuses as most of these diseases are highly infectious.
[The writer works in the Division of Communication and Vet Advisory Services within the Directorate of Veterinary Services; jothieno43@yahoo.com]
