Neosporosis
Also called Neospora abortion
A parasite infection that is one of the most common causes of abortion in cattle, especially in intensively farmed herds. Cows can pass it to their calves before birth, and dogs are involved in spread.
Cause and spread
- Cause
- The protozoal parasite Neospora caninum.
- How it spreads
- Dogs and coyotes are the final hosts and pass the parasite in their dung; farm dogs get infected from raw afterbirth or dead calves. Cattle swallow it from feed or water, and infected cows can pass it to the calf before birth.
Signs to watch for
- Abortion, most often in the middle of pregnancy, often in several cows in a short time
- Stillbirth, or weak calves with nerve and muscle problems
- Calves that look normal but are infected from birth
- Repeat abortion in some cows
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
In an aborted calf, the parasite is looked for in tissues (brain, lung, liver) and the placenta by PCR or special stains. After birth, blood tests for antibodies are used; comparing aborting and non-aborting cows helps in an outbreak.
- Usually the first testNeospora caninum Antibody ELISADetects antibodies in cows, to show exposure in an abortion outbreak or the herd.
- Confirms the diseaseNeospora caninum PCRDetects the parasite in aborted tissue or blood.
- Supports the diagnosisAbortion Panel (Brucellosis, Neospora, BVD) (panel)Looks at three common causes of abortion together.
Prevention and control
- Keep dogs and wild canines away from cattle feed and water
- Do not let dogs eat afterbirth or dead calves; dispose of them promptly
- Testing antibody-positive animals and culling those with a history of abortion can be considered, weighing cost and benefit; replace them with antibody-negative animals
- Blood-test calves at 5 to 6 months to find infected animals
- There is no approved treatment or vaccine, and removing infection from a whole herd is usually impractical, so control rests on accurate diagnosis and stopping spread
Where this information comes from
- Neosporosis in Cattle · Merck Veterinary Manual
- Abortion in Cattle · Merck Veterinary Manual
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.