A silent thief could be lurking in your herd. If you’re not careful, the sneaky culprit could steal tens of thousands — maybe even hundreds of thousands — of dollars from your pocket.

The thief, known as neosporosis, is still in its teenage years, having first been identified in 1988. However, it quickly became an old pro at infiltrating dairy operations and stealing profits.

According to the results of a California field study, neosporosis, a disease caused by a coccidian parasite known as Neospora caninum, accounts for about 40,000 abortions annually — or about 42 percent of all abortions — in California, says Les Choromanski, veterinarian and Neospora vaccine manager for Intervet, Inc.

At an average cost of $850 per abortion, that can result in significant economic loss. According to the results of the field study, those 40,0000 Neospora-related abortions cost California dairy producers about $35 million each year. “I know one dairyman who (lost) close to $250,000 dollars in lost milk and calves,” says Garrett DeVries, owner of Mira Vista Dairy in San Jacinto, Calif.

In addition to reduced milk production and lost calves, neosporosis also increases the cost associated with rebreeding cows that aborted and the cost associated with replacing infected animals that were culled from the herd.

Neosporosis also is costly to the beef industry. Research at Texas A&M University indicates neosporosis steals $37 million per year from the Texas beef industry.

Neosporosis does not limit its destruction to dairy herds in California and beef herds in Texas. Unfortunately, it is much more widespread. “We know Neospora caninum is worldwide — you’ll find it wherever you find cattle,” Choromanski says. “The rate of infection is unpredictable,” he adds.

At a cost of $850 per abortion, losses due to neosporosis must be taken seriously.

Preventing dogs — the definitive host in the Neospora caninum life cycle — from contaminating feed and water sources and rigorously culling cows that abort their calves are good control measures.

A conditionally licensed vaccine, developed by Intervet, also is worth considering. In field trials, the vaccine has been shown to reduce Neospora-induced abortions and eliminate the transmission of neosporosis from cow to calf. In a 107-cow herd in Minnesota, for example, the vaccine reduced the number of abortions from 27 per year to four. And of those four, none were associated with Neospora caninum. Another field trial, involving 757 cattle from seven herds throughout the U.S., indicates the vaccine is safe for use in healthy, pregnant dairy cattle. The vaccine is on track to receive final approval by the USDA by the end of the year.