Blue-Green Algae Dangers: Ensuring Your Dog Can Safely Swim in Water

dog by water

The dog days of summer are behind us, but there are still plenty of warm days ahead for pups to dip their toes in their local pond, or doggy paddle at their nearest lake.

While many dogs enjoying leaping into water – either playing with other pups, chasing sticks, or just relaxing — these cooling pools can harbor some hidden risks, with one of the most deadly being blue-green algae.

So before you let your bestie dive in for a swim again, it’s time to take a look at blue-green algae and why dogs should stay away from it.

Related: How to Teach Your Dog to Love Swimming

The Sneaky Threat of Blue-Green Algae

Blue-green algae is one of the scariest things your dog can potentially find in water. That’s because blue-green algae release toxins can severely harm dogs when ingested.

“Blue-green algae is a cyanobacteria that can overgrow in lakes, ponds, and rivers during summer and early fall months producing algae blooms,” says Dr. Carly Fox, Senior Veterinarian in Emergency & Critical Care at Schwarzman Animal Medical Center-NYC. “The algae blooms produce two types of toxins, microcystin and anatoxi, which can cause significant toxicity if ingested or swam in.” 

Blue-Green Algae and Dogs

According to Dr. Fox, blue-green algae poisoning is a very real and potentially fatal toxicity to animals. She adds that common signs of toxicity include vomiting, diarrhea, inappetence, lethargy, collapse, difficulty walking, trouble breathing, foaming at the mouth, and possible seizures. “The two toxins produced by cyanobacteria can lead to hepatic, or liver, and neurologic injury,” Dr. Fox adds. “If severe enough, animals can require intensive hospitalization and even die.”  

Indeed, stories of dogs dying from blue-algae poisoning tend to pop up during warm weather, as a warning to other dog parents to stay away. Texas has reported a number of dogs dying after swimming in blue-algae infested waters. North Carolina saw three dogs die in 2019 after jumping into a pond. One family mourned the loss of their beloved pet in Georgia. And the list goes on. While many of the reports are in the hot southern states, blue-algae can be found all across the U.S.

If you suspect your dog has signs of blue-green algae toxicity after a swim, Dr. Fox recommends contacting your veterinarian immediately. Also, rinse your dog’s skin and fur with fresh water, and do not allow your pup to lick their fur. After calling your vet, you can also contact the ASPCA Animal Poison Control Center at 1-888-426-4435 or the Pet Poison Helpline at 1-855-764-7661 for additional assistance.

Early detection and action can make all the difference, but the Centers for Disease Control and Prevention (CDC) point out that there’s currently no specific antidote for blue-green algae toxicity, and that medical treatment is mainly supportive. 

Related: Could Your Dog Die From Swimming in a Pond?

How to Prevent Blue-Algae Exposure for Your Dog

One of the best ways to ensure safe swim days is by staying updated. After all, an informed dog parent is a smart dog parent. If the local swimming areas are known to be unsafe, you should simply avoid swimming there. 

Otherwise, Dr. Fox recommends checking local advisories or websites or contacting your local park authority and asking where safe swimming holes are. 

Keep your Eye on the Water 

If you approach a lake or pond and notice that the water is stagnant, has a weird color, or perhaps even gives off a strange smell (yet dogs may be attracted to it), it is best to avoid letting your dog take a dip.

“If there are large amounts of bloom, it is usually visible,” says Dr. Fox. “However, small blooms may not be obvious, and sometimes algae can look mixed in with the water giving it a ‘pea soup’ consistency.” In those cases, Dr. Fox points out that you won’t be able to see any roots or individual cells, which can sometimes make identification difficult.  

Blue-Green Algae and Dogs pond

If you are unsure when assessing a body of water, you can look for nearby signs of current swimming conditions. “If there is any visible scum, blooms, foul odor, or foam, swimming should be avoided,” Dr. Fox says. “Swimming in areas where there is clear water, running water, and no visible blooms is preferable.”   

If you’re unsure, best to keep your dog out of the water. 

Post-Swim Bathing Ritual for Your Dog

After an adventurous swim, give your dog a good rinse. “If your dog swims in any suspicious bodies of water, make sure to bathe them directly afterward and monitor for signs of toxicity,” Dr. Fox explains.   

This helps wash off any potential hazards that might cling to their fur. Consider it a mini spa session for your furry buddy after their aquatic adventures. 

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Related: Must-Know Summer Grooming Tips, According to a Pro

No Drinking Allowed for Your Pup

A bit tough for water-loving dogs but teaching your canine companion not to drink from unknown water sources is crucial. Always carry fresh water and a portable bowl with you so your pup can stay hydrated and less tempted to drink dirty water that could be filled with potentially harmful bacteria.  

Fun at Home

If you can’t find a safe swimming spot, why not bring the water fun directly to your backyard? It’s quick and easy to set up a doggie pool, which allows your pup to have fun in a controlled environment where you know the water’s source and quality. Add some toys, and you have the perfect recipe for hours of safe and refreshing play. But of course, always supervise your dog.

One thing to note: Backyards can also be a haven for blue-green algae. Make sure to dump out stagnant water in plant containers, birdbaths, and fountains to prevent blue-green algae growth at home.

When it comes to our four-legged pals, a splash of awareness goes a long way in ensuring their safety. By understanding the risks and arming yourself with knowledge, you can make sure that every swim is a happy and healthy one. So, let’s keep those tails wagging, ears flapping, and paws splashing—safely, of course! 

By Diana Bocco

Diana Bocco is a full-time writer and dog lover. She's certified in pet CPR, used to run a dog rescue group in Thailand, and currently shares her home with two rescue dogs. Her work has been published on PetMD, Animal Wellness, the Discovery Channel, and more. Find more on her website at

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