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Taking your dog to the local swimming hole to cool off and play fetch is a common summer activity — but the quality of the water could seriously hurt or even kill your pet.
The bottom line: Toxic algae kills dogs.
Ingestion of toxic algae from lakes and ponds is a deadly summer disaster that has happened over and over again the past few years.
Here are the stories of at least 12 dogs who have died from toxic algae since 2011:
- On Aug. 9, 2019, Melissa Martin and Denise Mintz of North Carolina lost 3 dogs within 24 hours after the dogs had played in a pond. According to CNN, their veterinarian says the culprit was poisoning from blue-green algae in the pond. “What started out as a fun night for them has ended in the biggest loss of our lives,” said Martin in a heart-wrenching Facebook post.
- Just a day later, on Aug. 10, 2019, Morgan and Patrick Fleming of Georgia took their Border Collie named Arya to Lake Allatoona, where Arya “had the best day playing ball and swimming around.” But then Arya began vomiting in the car on the way home. By the time they got to an emergency facility, the dog was already brain dead and could not be saved. Their vet strongly suspects toxic algae killed the dog. “We lost our fun, loving, and crazy girl to what we can only assume was a lake toxin such as blue green algae,” Morgan Fleming wrote in a post that went viral on Facebook.
- In late July 2019, at least 2 dogs died after swimming in Lady Bird Lake in Austin, Texas. The city eventually closed part of the lake, Red Bud Isle, in the days following the tragedy. But until it was closed off to the public, the area was described as a “horror show” by a woman whose dog had died. “There were hundreds of people at the park,” she told the Statesman newspaper. “I tried to tell as many of them as possible what happened. I probably looked like a crazy person.”
- In June 2015, 2 dogs became ill after playing fetch in Red Rock Lake in western Minnesota, and one of the dogs later died. The suspected culprit, once again, was blue-green algae, and officials warned people to keep pets and children away from water with algae.
- The year before, in summer 2014, yet another dog from Minnesota died after chasing tennis balls thrown into Prairie Lake. The playful pup, a 5-year-old retriever named Copper, “loved the water … and loved chasing balls,” but he started acting strangely and “the last couple times, he didn’t try to go get the tennis balls — he just laid down,” his family told reporters. Copper was dead within minutes. “The algae is right up under the dock by the shore, and it’s a bright-green slimy, bubbly substance,” the dog’s family said.
- In summer 2011, toxic algae in Lake Milford, Kansas’ largest lake, was said to be responsible for 4 dog deaths. A few humans had also been reported sickened. “People aren’t happy because they want to have fun, but our main responsibility is to keep people safe,” said a natural resources officer after the lake was closed just ahead of a big holiday weekend.
Here’s Morgan Fleming’s post in her own words and photos:
Toxic Algae Kills Dogs
Dangerous and sometimes deadly algae can show up not only in lakes but also in oceans, ponds, streams and lakes. Toxic algae can also bloom in your pet’s outdoor water bowls, so always keep them clean.
Summer heat often results in the overgrowth of algae. Although not all algae is bad, cyanobacteria, also known as “blue-green algae,” can be harmful and sometimes fatal to dogs and humans.
If your pet spends any time outside, please keep reading this article to become aware of where this algae is found and how you can avoid it. (You can also help by sharing this article now. Thank you!)
What Is Toxic Algae?
“Some algal blooms leave a film of muck on the surface and make the water ruddy, but others are difficult to immediately detect,” according to CNN.
What about trying to identify the toxic algae by its color? That’s not always possible.
Although the toxic algae is sometimes known as “red tide,” it’s not always red and occurs in many colors such as blue, blue-green, yellow or brown.
“Your typical lay person will not be able to tell one algae from another, or a good from a bad,” an expert told 11 Alive of Atlanta. “It just kind of behooves anybody that sees algae in a lake, in a pond, that they’d probably want to be cautious and just not expose themselves to it or to their pets.”
Toxic algae often emits a bad, smelly odor, but sometimes it’s odorless. Because the smell is not consistent, you should not try to identify it by its smell.
Cyanobacteria algae occurs in cloudy patches of algae. These blooms look like foam or scum floating on the surface of water. It can occur in patches or appear to cover the entire surface of the pond.
When Is It a Concern?
The toxic algae blooms typically appear in late summer and early fall in the Northeast, but they can appear at any time in warmer climates.
Heat is what causes the overgrowth of algae, so locations with warmer climates year round are more susceptible to cyanobacteria in the water.
Where Toxic Algae Grows
Unfortunately, the dangerous bacteria are not limited to one area. Toxic blooms have been documented all over the world.
Toxic algae can occur in any body of water but is especially common in freshwater ponds — a popular location to take your dog for a swim. Salty/brackish water is also known to harbor this bacteria.
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Signs Your Dog Has Been Exposed to Toxic Algae
If you are swimming with your dog and notice any of the following symptoms in the dog, contact a vet immediately:
- Vomiting or diarrhea
- Extreme thirst
- Skin or mucus membrane irritation
- Motor weakness or staggering
- Paralysis of the respiratory of muscular system
The video below shows a man on Lake Erie navigating through toxic algae:
Other Pond Dangers for Dogs
Other than the concern of cyanobacteria, there are other bacteria lurking in natural ponds.
Because natural ponds are visited by wildlife whose urine and feces host a number of illnesses, contagious bacteria and diseases, ponds are breeding grounds for concerning bacteria. When your dog drinks that pond water, they are at risk for contamination.
Some of the common bacteria found in natural ponds are:
- Giardia: A common bacterium found in contaminated feces, once ingested it can cause lasting diarrhea. If you suspect your dog has giardia, have your vet test the dog’s stool.
- Coccidia: This is transmitted from dog to dog through feces. Coccidia can lie dormant in the dog’s body undetected but causes lasting diarrhea. It can also be found by fecal test done by your vet.
- Leptospirosis: Natural water contaminated with infected wildlife urine can cause severe illness in dogs when ingested. A vaccine is available to protect your dog against leptospirosis contamination.
Despite the handful of concerns surrounding natural pond water and allowing your dog to take a dip, we’re not suggesting that you not let your dog swim. Part of being a responsible pet parent is understanding the risks involved in your decisions.
If you suspect your dog has been exposed to toxic algae, contact your vet for instructions on how to ensure your dog’s health and safety.
Finally, help us raise awareness of this summer danger by sharing this article on Facebook now. Thank you!
This pet health content was reviewed for accuracy by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. This article was originally published in 2015 and is regularly updated. It was last reviewed for accuracy and updated Aug. 12, 2019. 
