Suspect neosporosis if any of your cows aborts or is infertile. Neosporosis is the most common cause of abortion in cows in this country. In fact it accounts for almost half the cattle abortion cases diagnosed in veterinary laboratories, and it causes huge losses in the cattle industries.
The typical abortion rate on Neospora infected farms is about 7% but abortion rates of up to 30% have occurred.
What's the cause?
Neosporosis is caused by a tiny one-celled parasite called Neospora caninum.
When a cow is infected, she may appear normal but when she gets pregnant her foetus is likely to die. If the foetus dies early in pregnancy it will be absorbed, an older foetus may be aborted or it may dry up in the womb (mummification). Sometimes it goes full term and is born looking normal, but it is infected. If that infected calf ends up as a replacement heifer, the heifer is likely to pass the disease on any calves she has while they are in her womb. They in turn may die in the womb or they may be born apparently normal but infected……and so the cycle continues.
What are the effects of neosporosis on the cow?
The cow may show no signs of infection other than:
- Abortions, stillbirths and mummified foetuses
- Infertility because of early foetal death
Neosporosis might also cause a drop in milk production in infected cows and slowing of the growth of young infected cattle.
Most Neospora abortions occur in cows 4 years old or younger, usually in their fifth month of pregnancy.
If your cow aborts…
Your vet will investigate and might decide it's worth checking for neosporosis by doing blood tests.
If the disease is confirmed, you can:
- Cull the infected cow.
- Treat her to eliminate infection.
- Vaccinate young stock and cows coming onto the farm.
- Do nothing
Your vet will advise which options to take, depending on your farming goals and economics.
How is it spread?
Although the name suggests that dogs play a part in spreading Neospora caninum infections and indeed some dogs and maybe some other wild mammals can probably transmit the disease in their faeces, vertical transmission from cow to calf is very much more common, accounting for over 90% of cases.
To prevent the disease:
- Don't allow dogs to defaecate on pasture that will be grazed by female cattle. If they do, remove the faeces from the pasture.
- Don't allow dogs to eat any aborted calves, membranes or raw beef. The parasite lives in muscle and other organs of infected animals. Even if an infected cow has died from other causes e.g. bloat, dogs could still be infected by eating her meat.
- It's wise not to buy in cows that have aborted in the past in case they are carriers of neosporosis.