Norwegian authorities were advising dog owners to keep their pets from interacting with other dogs Tuesday, as hundreds of dogs were sickened by a mysterious — and potentially contagious — bowel disease that has turned deadly in a growing number of cases.

The number of dog deaths had risen to 26 by late Tuesday, according to a representative from AniCura Norge, a veterinary hospital in Oslo.

Post-mortem examinations have failed to provide answers, according to a statement Tuesday by the Norwegian Food Safety Authority. What was clear was that hundreds of dogs across Norway were exhibiting symptoms that included vomiting, diarrhea and fatigue.

As many as 200 dogs have suddenly fallen sick, Norway’s Veterinary Institute told Agence France-Presse.

Veterinarians in the Oslo area began reporting sick dogs to the Norwegian Food Safety Authority this month. Since then, dogs in Bergen on the west coast, in the northern municipality of Nordland and a dozen other towns have fallen sick.

In a statement Tuesday, the food safety authority said that “a mixed culture” of two types of bacteria, Providencia alcalifaciens and Clostridium perfringens, was found in some dogs’ guts. The bacteria are sometimes associated with diarrhea in people as well as dogs.

Advertising

“But we can’t conclude that these are the cause of the symptoms we see,” the statement said.

At one point investigators hypothesized that the disease might be connected to an unusually large number of wild mushrooms growing this year. This theory remained under consideration Tuesday, along with bacteria, viruses and parasites, according to the Norwegian Food Safety Authority.

Salmonella and rat poison have been ruled out, according to the Norwegian Veterinary Institute.

It’s not yet clear how the illness is spreading, if it’s even contagious and whether the cases are related, according to authorities.

But the Norwegian Food Safety Authority urged pet owners to avoid allowing their dogs near “dressage courses, exhibitions, hunting trials and the like” until more answers emerge.

Torstein Holten of Hamar told Norwegian broadcaster NRK that her 7-year-old dog Lexi had been perfectly healthy when she took her for a run one day last week. A day later she was vomiting and riddled with diarrhea.

After seeing her Thursday, a veterinarian told the family to bring her back if her symptoms worsened. The next morning, the Holten family found her dead in the hallway.

In an attempt to figure out what’s going on, the Norwegian Veterinary Institute is asking 2,000 veterinarians to complete questionnaires. The illness is not believed to affect human beings.