Ask the Vet

Stray Dogs, Coyotes May Spread Disease

Coyotes or stray dogs may spread Neospora, a protozoan that causes abortions in cattle. (Getty Images stock photo)


We are seeing more dogs on our farm, and I often hear coyotes at night. I found what looked to be dog manure on top of a hay bale. Do I need to worry about Neospora infecting my cow?


First, let's make sure everyone knows what Neospora is. This a protozoan (single-celled organism) that can cause abortion in cattle. It has a weird life cycle, and dogs and other canines are the "definitive host." They become infected by eating cattle, chicken, deer and other wildlife.

In dogs, Neospora undergoes sexual reproduction, and the oocysts (protozoan eggs) are shed in the stool. These oocysts can exist in the environment for extended periods.

Cattle can be infected from contaminated pastures, water, hay and feed, but "vertical transmission" from the dam to her calf is the most common method. If an abortion does not occur, more than 90% of calves born to infected dams will also be infected.

Some of the signs you might see if Neospora is present in the herd include premature or stillbirths, abortions (especially between 5 to 7 months) and calves born with brain disease. Any aborted or stillborn calves should be necropsied. While cows do not show any signs of this infection, there is a good serologic test to identify them.

As to prevention, the focus should be on protecting feed and water supplies from dogs and other canines. Good sanitation is essential in feeding areas and troughs. Pasture rotation and paying attention to stocking density can also reduce potential of environmental infection. Dead cows, dead calves and placentas should be promptly and properly disposed of. If Neospora is detected, infected cattle should be culled and calves only kept from seronegative cows.

So should you be worried about Neospora? Probably not. More likely, you should be laser-focused on every disease and management practice that could affect herd reproduction. At the very top of this list is proper nutrition. Also critical is a solid biosecurity program including the right vaccines at the right times to keep diseases out and/or prevent the preventable.

Another key is a controlled breeding season. This calls for careful observation of cows in heat and noting whenever an excessive number come back into heat after being bred. At the end of the season, preg-check cows to confirm pregnancy percentage. With good management, your goal should be a 90% to 95% calf crop. Anything less, or a sudden decrease in the herd pregnancy rate, demands quick and aggressive detective work.