Deer are Foaming at the Mouth Before Dropping Dead in Washington

Residents in Washington state's San Juan Islands have reported dozens of wild deer dropping dead in recent weeks after first showing signs of foaming at the mouth.

Wildlife experts have zeroed in on an explanation.

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Officials have confirmed the presence of a fast-spreading, deadly viral infection in the species in the San Juan Islands.

The viral infection, known as adenovirus hemorrhagic disease (AHD), was first discovered in California in 1993 and is specific to the deer family. Lab results from the Washington Animal Disease Diagnostic Laboratory at Washington State University confirmed the presence of the virus earlier this month.

"This is the first documented instance of this disease in Washington since the last outbreak in Goldendale in 2017," Washington Department of Fish and Wildlife (WDFW) veterinarian Kristin Mansfield said in a news release. "At this point, the disease appears to be localized to the San Juan Islands."

Similar outbreaks have been detected in Oregon and British Columbia, and cases usually rise in the summer before dropping in the fall. Signs of infection include rapid or open-mouth breathing, foaming or drooling from the mouth, diarrhea, weakness and emaciation. There is no known cure for the disease, and death usually occurs within three to five days after exposure.

Well north of 50 reports of sick or dead have been filed with the WDFW, and the virus has been confirmed on both San Juan Island and Orcas Island with suspected cases on Lopez Island. So far, the disease does not appear to have spread to the mainland.