Pictures of farm, cows on property

Read more on the initial investigation

OLYMPIA, WA. -- Washington State Veterinarian Leonard Eldridge says an investigation into the deaths of as many as 60 cows at a Stevens County dairy found no health threats to people or other animals.

Larry Storey, KREM.com

Cows on the grounds of an Addy dairy farm that is now under investigation.

But investigators also have no clear clue what caused the animals' deaths.

The dairy in Addy, about 75 miles north of Spokane, has not sold milk since December because the owner suspected heavy metal contamination of the cows' feed.

But Eldridge says a detailed investigation found no serious animal diseases or toxic contamination of the animals' feed.

He says veterinarians have not been able to identify a common cause of death and may never know.

Eldridge suggested that the dairy owners take steps to improve the farm's sanitary conditions and seek expert advice on herd health management and nutrition.

AP file photo

A dairy in Addy, WA is the subject of a state investigation.

Lab tests determined the feed is safe to give to cattle and contains the right amounts of nutrition.

Earlier tests found no presence of foreign animal disease, mad cow disease or any other potentially fatal diseases.