All About Dogs

Will Deadly Blue-Green Algae Kill My Dog?

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There is nothing that makes dog-moms and dads take notice like a post on dogs dying.  If you’ve been on social media this summer, you’ve probably seen a story on Arya, the sweet dog who swam in Lake Allatoona and died less than an hour later.

Yes, summer may seem like the perfect time for a water outing with the pups, but at least one dog in Georgia and at least three dogs in North Carolina have died within hours of swimming in ponds and lakes with algae.  Toxic blue-green algae has been blamed for their deaths.

Is it safe to take your dogs swimming anymore? 

The verdict isn’t clear, but here is the information that has come in.

What is Blue-Green Algae?

Blue-green algae is the term for a toxic microscopic bacteria that grows in water.  This cyanobacteria is harmful to both dogs and humans, although it is more often fatal to dogs.

(Blue-green algae is NOT present in this photo) Photo is Meeko swimming in Lake Lanier.

If you suspect any blue-green algae in the water, do not let your dog swim in it or drink the water.  KEEP AWAY!

If a dog ingests the algae, dogs can die within the span of an hour, oftentimes before owners can rush them to a vet.

Where is Blue-Green Algae?

Blue-Green algae is more prolific in stagnant or slow-moving warm water, specifically in lakes, ponds, and slow-moving streams.

It is naturally occurring and can grow anywhere in the world; it is not limited to specific regions, and has popped up in various states in the U.S. (northern states included) and in other countries. 

Though blue-green algae occurs in freshwater, another version of dangerous cyanobacteria can grow in saltwater as well – it just may not look blue-green. 

We live in Georgia, and a handful of lakes in the area are being tested for blue-green algae.  Lake Olmstead in Augusta, Georgia has tested positive for the presence of four types of dangerous bacteria, including toxic algae.  Testing is still in process for Lake Allatoona.1 Lake Lanier has no reports of harmful algae blooms and is closely monitored, although it is unclear whether testing has been done.2

When to Worry About Blue-Green Algae?

Blue-green algae tends to bloom at the end of summer, when temperatures are at their hottest.  Beware especially if it’s very hot outside with little rainfall; this provides the perfect conditions for the algae to grow.  The cyanobacteria prefers water temperatures above 75 degrees Fahrenheit, so can grow quickly in summer and early fall, and other times of the year when conditions are right.3

Signs of Blue-Green Algae

Although it’s difficult to tell if blue-green algae is present without testing the water (it is invisible to the human eye unless it has clumped together), here are a few signs it may be looming.

Water that looks like pea soup or spilled green paint may be a warning of blue-green algae bloom.  In addition, if you see thick mats of scum spread across the top of the water, or dead fish, keep your dog away. 4

(Blue-green algae is NOT present in this photo) Photo is Meeko swimming in Lake Lanier.

Is it always toxic?

Most blue-green algae do NOT produce harmful toxins.  However, there is no way to determine whether it is harmful without testing, so all blue-green algae blooms should be considered potentially toxic and avoided.

Why is Blue-Green Algae So Deadly to Dogs?

Blue-green algae can sicken dogs rapidly, killing them even before they can make it to the vet.  Even a small mouthful of algae-contaminated water can result in fatal poisoning.

The algae can cause liver failure or respiratory paralysis, which can cause death within hours or days.  Earlier symptoms are vomiting, diarrhea, seizures, disorientation, difficulty breathing, shock, and muscular symptoms.  If you suspect it, bring your dog to the vet as fast as you can.

There is no antidote for the toxins created by blue-green algae.  Even if a dog survives the toxins, they likely will suffer long term health problems.

While most fatal to animals, the algae is harmful to humans too, and can cause rashes, vomiting, diarrhea, eye irritation, and headache.5

Did Blue-Green Algae Kill Arya?

An autopsy was not performed on Arya, the border collie who died after swimming in Lake Allatoona.  The veterinarian determined it was indeed a toxin that caused her death, but has not conclusively established that blue-green algae was the culprit.

However, the Georgia Environmental Protection Division (EPD) did find blue-green algae from the cove where Arya had been swimming.  A sample is currently being tested. 6

Where Is It Safe To Swim With Your Dog?

Without every lake in the area being regularly tested for harmful bacteria, it is difficult to know where you can safely bring your dog to swim.  Here are some alternatives with less risk of blue-green algae.

The Beach

Lakes and ponds may be convenient, but they most often have the stagnant, warm water that provides the best growth conditions for blue-green algae.  Beaches, obviously, have constantly moving waves of churning ocean water.  So, there is less opportunity for blue-green algae to bloom. 

However, beaches still carry the risk of other dangerous bacteria that are less common and less fatal than algae.

The Dog Swimming Pool

If you can find a dog-friendly swimming pool in your area, these are great alternatives to the lake!  In well-maintained pools, the water is cleaned regularly and presents almost zero opportunity for blue-green algae to grow.

A swimming pool is not without faults, though.  Depending on how many dogs swim in the pool, it can be breeding ground for other germs.  For instance, if one dog has worms, they can contaminate the water.  Since a swimming pool is a small volume of water, it could potentially infect any other dog that ingests any water from the pool.

Other Swimming Dangers to Dogs

Before the vet concluded that a toxin caused Arya’s death, there was widespread speculation on whether algae was indeed the culprit.  A lot of people, myself included, wondered whether Arya succumbed to water intoxication.

The Dangers of Water Intoxication

Water intoxication can also be fatal if not treated quickly.  It occurs when a dog has ingested too much water.  So, this happens most commonly when a dog has been swimming or playing in water for a long time and has drunk more than his body can handle.  It is just as dangerous as dehydration, although less common. 

To avoid water intoxication, monitor your dog while swimming or playing in the water.  Make sure they have regular rest breaks, particularly after they have ingested water or emptied their water bowl.

Saltwater Poisoning

Similar to water intoxication, saltwater poisoning, or saltwater toxicity, occurs when a dog ingests too much saltwater.  The excessive salt in their body can cause vomiting and diarrhea (commonly) but can progress dangerously to neurologic issues.  Saltwater poisoning can also be fatal if untreated.

To avoid saltwater toxicity, make sure your dog does not ingest too much saltwater.  Instead, offer them plenty of cold fresh drinking water as often as possible.

Better Safe Than Sorry

While risks exist everywhere, deadly blue-green algae is one I’m not sure I’m willing to take.  If you venture out to the lake, be on the lookout for any of the warning signs listed above. 

Note that many organizations in charge of lake water have been inundated with questions lately.  It is possible that testing has been done or is underway to determine whether blue-green algae is present. 

Ask them – check their websites or Facebook pages, or give them a call or email – as a negative test result may be the best peace of mind you can get before jumping into the water.

Be safe out there – we love ALL dogs and care about their well-being!

Are you considering a trip to the beach?  Read our article on Reasons Why Fall Is the BEST Time to Take Your Dog to the Beach


1 Lake Lanier, Harmful Algae Blooms on Lake Allatoona

2 Gainesville Times, Why pet owners near Lake Lanier can relax about toxic algae

3 Minnesota Pollution Control Agency, Blue-green algae and harmful algal blooms

4 Blue Cross, Blue-green algae and its dangers to dogs

5 Pet Poison Helpline, Blue-green Algae (Cyanobacteria)

6 Atlanta Journal Constitution, Dog’s death points to possible toxic algae bloom in Allatoona Lake

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