Samples of water taken from eight locations at Twin Brook and Knight’s Pond Preserve in Cumberland tested negative for toxins associated with blue-green algae, which had been suspected of poisoning two dogs after they swam at the Twin Brook recreation area, quickly became ill and were euthanized.

It means the mystery of what sickened the dogs will linger until analysis is complete on tissue samples taken from one of them following its death last Wednesday after suffering seizures and other complications.

The town of Cumberland hired an environmental consultant this week to test the water at the popular green space and erected signs warning of a possible toxic bloom. The consultant, Kristie Rabaska, collected eight samples Tuesday from Twin Brook and nearby Knight’s Pond Preserve and performed rapid tests similar in form to an at-home pregnancy test.

The town of Cumberland put up signs at Twin Brook Recreation Area on Monday warning park-goers of potentially toxic blue-green algae in the water in the park’s brooks. Brianna Soukup/Staff Photographer

The negative tests mean the public shouldn’t blame algae yet, and it’s possible that something else in the water or park sickened the dogs, according to a state lakes biologist who is monitoring the testing, and a veterinarian who treated a third dog that became ill but survived.

During a visit to Twin Brook, Linda Bacon, a lakes biologist for the state Department of Environmental Protection who is assisting the testing, said she found several pools of stagnant water, and said that recent bursts of rain may not have generated enough runoff to wash away concentrations of other potentially harmful organisms living in the murky shallows. But that doesn’t mean the water is toxic or that algae is to blame.

“There’s all kinds of pathogens that could be in those pools, and the likelihood of encountering them is much greater than encountering (toxins) from blue-green algae,” Bacon said.

The tests conducted this week looked for three particular toxins – microcystins, nodularins and anatoxin – that are specific to blue-green algae and most likely to be found in Maine, Bacon said.

The tests did not look for other organisms that can cause illness, such as salmonella, E.coli or the parasite that causes giardia.

Elayna Girardin posted a warning on a community Facebook page after she had to put both of her dogs down last week when they became sick after playing in the water at the park in Cumberland. Brianna Soukup/Staff Photographer

The trouble began after Elayna Girardin, who lives near Twin Brooks, took her two dogs to swim near the Greely Road side of the park on Aug. 21. Both dogs swam or waded in murky water, Girardin said. About a day later, both showed signs of poisoning, and within three days, Girardin euthanized her smaller dog, Luna, a 25-lb Chihuahua mix after she experienced seizures.

Her larger dog, Stella, a 45-lb boxer-pit bull mix, was euthanized six days after swimming in the water. Stella showed similar symptoms – she stopped eating and drinking, her muscles became stiff, she drooled excessively and showed signs of internal bleeding, Girardin said.

Girardin’s veterinarian asked to perform a necropsy of Luna and took tissue samples from her organs that can be more closely analyzed for traces of pathogens. After the post-mortem examination, Girardin said, the vet seemed sure that the illness was caused by blue-green algae toxicity, and said there were signs of liver and kidney failure. She said one dog tested negative for leptospira bacteria, which can cause similar symptoms.

Girardin posted online about the death of her dogs and the indication that the algae bloom was to blame. The online post caught the attention of town officials.

After hearing the negative results, Girardin said she didn’t know how to feel, and wondered about the other variables at play.

Could the recent downpours after her visit Aug. 21 swept away algae that had harmed the dogs? Did they eat something, or ingest another pathogen entirely? She felt stumped, she said.

“It’s tough,” Girardin said. “At least I had an answer, and now I don’t have an answer.”

A third dog that was in the park this weekend became ill but recovered. The dog’s owner, Tracy Silverman, said she took her pet in for preventive treatment and testing after seeing Girardin’s notice online.

Dr. Megan Vaught, a veterinarian at the Maine Veterinary Medical Center in Scarborough who treated Silverman’s dog, ran a standard blood-work panel that showed the pet’s liver enzyme levels were abnormal. But the levels themselves are not conclusive that algae was responsible. Abnormal liver enzyme levels can be caused by something as simple as an upset stomach, Vaught said.

Blue-green algae is among the most common in the world and is found virtually everywhere. Not all blooms of blue-green algae produce toxins, and scientists are still studying why some blooms create the poisonous substances and others do not.

Dogs typically ingest the algae by drinking lake water or consuming bits of the plant matter when it’s left on their coats. Dogs are also attracted to the pungent stink the plant matter gives off when clumps float to the surface and rot. Humans, who rarely drink large quantities of unfiltered lake water, are less likely to become ill, but can still be affected.