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.