Minutes after the 5-year-old yellow Lab got to the shoreline of Prairie Lake, he vomited.
Then he fell over and couldn't get up, said the dog's owner, Kirsten Tatge of Clear Lake, Minn. Shortly after being taken to the veterinarian, Copper the Lab died.
Although the cause hasn't been confirmed, Tatge's veterinarian suspects the dog ingested toxic blue-green algae that was in the lake.
The Minnesota Pollution Control Agency on Thursday advised keeping pets away from lakes, ponds and slow-moving streams covered in blue-green algae blooms. The blooms often look like green paint, pea soup or floating mats of scum.
Although not all blue-green algae is poisonous, MPCA officials say it's difficult to visually identify the toxic algae, which can be deadly to dogs, livestock and other animals within hours.
Animals may end up ingesting the toxins if they drink the water or lick their coats after emerging from the water.
Blue-green algae blooms can occur anytime during the summer but more often are associated with warm weather and low rainfall. When waterways develop high levels of nutrients, algae blooms.
"This year's unusually heavy rainfall has carried tremendous amounts of nutrients into Minnesota lakes," said MPCA scientist Steve Heiskary. "If the rain slows down and we move into a period of hot, dry summer weather, we could see an exceptional number of algae blooms across the state in the coming weeks, even in lakes that do not normally experience them."