Editor's note: This story was updated Aug. 27, 2019 with warnings about toxic algae blooms in several New York City parks.
Aug. 14, 2019 -- A deadly variety of algae has caused a recent spate of dog deaths in the Southern United States, causing concern among canine owners nationwide.
A dog died last Wednesday in Texas after wading in a shallow pool near a river; three dogs died in Wilmington, NC, after a trip to a pond last Thursday; and another died after swimming in Lake Allatoona in Georgia on Saturday.
The killer is blue-green algae, or cyanobacteria, that can be found in fresh or salt water and contain toxins that can be fatal to dogs within minutes, hours, or days of exposure.
These primitive algae are considered harmful algal blooms (HABs) and evolved roughly 3.5 billion years ago, says Larry Brand, a University of Miami marine biology and ecology professor. Although they can also be deadly for humans, dogs are far more likely to ingest them.
“What people see typically is they can float up to the surface and form a kind of scum,” Brand says. “They’re usually greenish in color with bluish tints. It’s thick, gooey stuff; people know not to drink it.”
The blooms were also found in three New York City parks in late August -- two in Manhattan and one in Brooklyn. Officials urged residents to avoid the waters of Turtle Pond and Harlem Meer in Central Park, the pond in Morningside Park, and the large pond in Prospect Park in Brooklyn.
Blue-green algae are commonly confused with green algae -- both can create dense material on the water’s surface that can interfere with activities like swimming and fishing, and may have a similar smell, the Environmental Protection Agency says. But, unlike green algae, blue-green algae can be fatal.
According to veterinarians, these toxic algae have been killing animals for over 100 years -- but it’s becoming more common, Brand says.
An increase in untreated sewage and the use of crop fertilizer are causing the harmful blooms to grow. Rising temperatures due to climate change also contributes because the algae grow in warmer weather.
“On a global scale, they’re getting worse,” Brand says. “So you get more incidences of dogs dying.”
The most recent incident happened Saturday, when Morgan and Patrick Fleming took their border collie, Arya, to play ball in the Georgia lake and escape the heat. When Arya vomited and defecated in the car on the ride home, they took her to the emergency department. By the time they got there, she was brain dead.
“We lost our fun, loving, and crazy girl to what we can only assume was a lake toxin such as blue green algae,” Morgan said in a Facebook post.
Melissa Martin and Denise Mintz had a similar experience in North Carolina. The two took their dogs Abby, Izzy, and Harpo to a pond in Wilmington, and within minutes of leaving the pond, Abby, a West Highland white terrier, had a seizure. Izzy and Harpo began seizing shortly thereafter, and Harpo went into liver failure.
The algae produce two different toxins: one that causes neurological problems, and one that leads to liver failure, according to David Dorman, a professor of toxicology at North Carolina State University College of Veterinary Medicine.
Signs that a dog has ingested blue-green algae include twitching, weakness, seizures, vomiting, and diarrhea. Although it is more common to see symptoms within minutes or hours, it might be days before the toxins take effect.
“One of the first cases of algae killing a dog was in 1920,” Dorman says. “It’s a problem that’s been around for a long time, and it’s all too common.”
Dog owners should keep their eyes peeled for water discoloration and dead fish floating in the water, Dorman says. The algae may also produce a foul smell. But, unfortunately, he says, it isn’t always visible -- the algae may lurk in the bottom of the lake attached to sediment or other plants.
The wind may blow them onto the soil as well, so areas near the water may also be dangerous for dogs, says Val Beasley a professor of veterinary, wildlife, and ecological toxicology sciences at Pennsylvania State University.
“Dogs will lick them from the water, lick them off their fur, and they will sometimes eat them off of these other surfaces and can readily be poisoned that way,” he says.
He explained the algae that cause neurological problems act like very potent nicotine, causing twitching and paralysis. Those that affect the liver cause the animal to hemorrhage to death.
Beasley say dog owners seeking treatment for their animals should consult both a veterinarian and an animal poison control center, because not all vets have dealt with algae poisoning.
“Many of these animals will be dead on arrival,” he says. “But if you don’t try, you can’t save them.”