Some dogs like to jump in the water to cool off on a hot day.
But one North Carolina dog owner learned the dangers associated with that the hard way.
"My whole world revolved around those dogs," Melissa Martin told ABC11.
It was only natural that she spent last Thursday afternoon at a Wilmington pond near her neighborhood with her pups Abby, Izzy and Harpo.
But when they got home, it was clear something was wrong.
"One of the Westies started like trembling really bad so I jerked her up and rushed to the emergency vet," Martin said
The veterinarians were able to determine all three dogs had blue-green algae poisoning -- also known as cyanobacteria -- from the pond. The algae produces a chemical toxic to humans and animals.
"There's some places you can look at the water and see blooms that come up really quickly and that will be obvious or the water looks discolored," said Dr. Kate Aicher with VSH of the Carolinas. "But that's not always a guarantee and there may be some water sources that could have some degree of blue-green algae and potential for toxicity that owners wouldn't be able to recognize that quickly."
She said sometimes you'll be able to see the blooms but other times the water will be clear, which was the case for Martin.
According to the CDC, cyanobacteria live in fresh and saltwater.
The North Carolina Department of Health and Human Services said children and dogs are the most susceptible.
The CDC said cyanobacteria usually multiply and bloom when the water is warm, stagnant and filled with nutrients from sources like fertilizer runoff or septic tank overflows.
Symptoms include vomiting, diarrhea, weakness, difficulty breathing and seizures.
Now, Martin is hoping her story will help prevent this from happening again.
"I can't lose these dogs for no reason," she said. "That's why this is now my focus because I can't just sit around and just think they died for no reason. There has to be a reason."
Martin is reaching out to her local legislators to try to get signs warning of the dangers near ponds. She hopes to bring it to a national level too.
Vet says toxic blue-green algae that killed 3 dogs can be hard to recognize