Somewhat of a mystery still surrounds the cause of death of a dog who reportedly ingested river water off of Sand Island in early August.

The Oregon Health Authority initially believed the dog’s death was a result of cyanobacteria, a harmful algae. But after further testing, the agency reports no cyanotoxins in the water.

A border collie nearly 3 years of age, Jax, died Aug. 4, after a day in the water off the north point of the popular island, across from St. Helens. Cyanobacteria, also referred to as blue-green algae, thrive in nutrient-rich water and pets, such as Jax, can be particularly vulnerable, due to their small size.

OHA spokesperson Jonathan Modie said Tuesday, Aug. 20, that sampling over a week after the dog’s death found no harmful cyanotoxins in the water near Sand Island.

“Based on results from last Monday’s (Aug. 12) sampling event that showed non-detections of cyanotoxins on the Oregon side of the Columbia, adjacent to Sand Island, and very recent observations by Port of Ridgefield staff along Lake River indicating no bloom present, OHA has determined there is no justification for further sample collection at this time,” Modie said.

‘There one day, gone the next’

So then what did kill Jax? Well, it might be hard to say. And the answer still may be cyanobacteria, even with OHA’s recent findings.

Stuart Dyer, senior advisor with the Healthy Waters unit of the OHA, said that testing can be difficult because of factors within the bodies of water themselves.

“Small pockets of water, within much larger systems, can accumulate bloom material and that might be an ephemeral accumulation where we’re not going to catch it,” he said. “It might be there one day, gone the next. We do our best.”

The most recent sample in the Sand Island area was collected Aug. 12 and results came in later that week. Dyer said there are no plans to resample for another couple of weeks.

“Based on the results of very recent toxin testing, we have to go with what the data told us, and in this instance, it was telling us there wasn’t really grounds for additional follow up or sampling,” Dyer said.

Bring pets to water, with care

OHA was asked if it has heard of any other dog deaths resulting from ingesting of water in Oregon waterways.

“We generally don’t track dog deaths,” Modie said. “It’s sad for me as a pet owner, we do see dog deaths once in a while, sometimes every year, sometimes none. They do happen and, sadly, it’s very unfortunate.”

Modie pointed out that dogs have a low tolerance for cyanotoxins due to their size and level of activity and that dogs can get sick from low levels of cyanotoxins.

So even with no advisory for where you and your pet plan to recreate in the water, Dyer said to be conscious of the water. An algae bloom may make the water look foamy, scummy, thick like paint and green, blue-green or brownish red, according to OHA.

“We also tell people that when in doubt, stay out,” Dyer said.

The Midway Veterinary Hospital in Warren noted that the harmful algae can be toxic to humans and animals. Symptoms in dogs can include weakness, staggering, convulsions, difficulty breathing and sudden death.

Tanya Bachman, the owner of Jax, said that after her dog vomited and showed diarrhea, he had a seizure and went unconscious. Jax died within an hour.

OHA advises recreational visitors to continually be alert to signs of cyanobacteria blooms. Of particular importance is that blooms can develop and disappear on any water body at any time when bloom conditions are favorable. OHA shared advisory levels for harmful algal blooms at tinyurl.com/ybmc7yaa.