Neosporosis is one of the most common causes of abortion in both dairy and beef cattle in Ireland, according to Animal Health Ireland. It has been estimated that about 9% of all bovine abortions in Ireland were the result of the common parasitic infection.
As well as abortion, neospora infection commonly results in the birth of a full-term, apparently healthy calf that is congenitally infected.
Cattle can become infected with neospora in two ways:
- From cow to calf across the placenta during pregnancy (90%);
- Ingestion of feed or water contaminated by neospora oocysts in dog faeces (10%).
Once infected with neospora the cow remains infected for life. Any live full-term calf she produces may be born infected, allowing vertical transmission of the disease.
Infected animals have 2-3 times more chance of aborting than non-infected animals. They may abort more than once, but not necessarily in consecutive pregnancies.
Economic losses due to neosporosis:
- The potential value of aborted calves;
- Retention of barren suckler cows;
- Premature culling of breeding animals and consequent increased replacement rates;
- Reduced value of high genetic merit animals;
- Loss of milk associated with abortion.
Know the clinical signs
With no treatment or vaccine against neosporosis currently licensed, it is important to know the clinical signs of the parasitic infection. You can then take action to mitigate the effect it has on your herd.
Abortion is the main clinical sign. Aborting animals do not usually show any other clinical signs of disease.
Neospora may be associated with sporadic abortions or occasionally with abortion storms, in which up to one-third of animals abort over 2-3 weeks.
- Abortion (between 3 and 8 months gestation - often peaks at 5-6 months of gestation)
- Mummification (between 3 and 5 months gestation)
- Late embryonic death/early abortion (>45 days gestation)
Neosporosis can be suspected on clinical grounds but requires laboratory examination for confirmation. Suitable samples to submit for testing include:
- Aborted foetuses and placentas.
- Blood samples from animals that aborted and other non-aborting animals in the group.
- Milk samples from bulk milk tank or from individual animals.
Control of neosporosis:
- Identify infected carrier cows - infected cows will carry the infection for life;
- DO NOT breed replacements from infected cows and consider culling infected cows;
- Control access of dogs to calving cows and aborted material, as well as feed bins and silage.
- Blood test any purchased breeding stock for neospora – two blood tests are required to confirm that an animal is truly negative.
More information on Neosporosis can be found in the Animal Health Ireland online guide.