FieldDxNeosporosis (Neospora caninum)Clinical signs, differential diagnosis, treatment and prevention in cattle.
Overview
A major cause of abortion in cattle, transmitted congenitally or from dog feces contaminating feed. Neospora caninum, a protozoan parasite; dogs are the definitive host.
Clinical signs
- Sporadic or herd outbreaks of abortion (affecting 20% to 40% of the herd).
- Abortions occur between 3 and 8 months of gestation (mean 5.5 months).
- Fetuses are often autolyzed, showing widespread histologic inflammatory lesions including nonsuppurative necrotizing encephalitis and myocarditis.
- Calves may be mummified or born full-term with or without clinical signs.
- Repeat abortions can occur in the same cow.
Predisposing factors
- Worldwide distribution.
- Vertical transmission (congenital) during pregnancy is highly common; acquired postnatal infection also occurs.
Look-alikes to rule out
Treatment
- In dogs, clindamycin has antiprotozoal activity against Neospora caninum tachyzoites and can be combined with trimethoprim-sulfa or pyrimethamine, though response is often partial or absent.
- In cattle, no approved treatment or vaccine exists; control relies on accurate diagnosis and preventing transmission (e.g. not breeding seropositive cows, controlling definitive-host dog access to feed).
Drugs mentioned: Pyrimethamine Clindamycin
Prevention
1. Screen and monitor herd mates (both aborting and non-aborting) using serology and immunohistochemistry to establish the role of Neospora in herd abortion outbreaks. 2. Prevent farm dogs (definitive hosts) from contaminating cattle feed or water with feces.
Source
A Textbook of the Diseases of Cattle, Horses, Sheep, Pigs and Goat by ELSEVIER (Passages 35, 36).
MSD Veterinary Manual — Neosporosis in Animals (accessed 2026-08-11)
Condensed and attributed, never reproduced whole. Open the full entry in the app.