Blue Green Algae and Dogs: What to Know

When it comes to blue-green algae, it may not be the first thing pet parents think about when considering potential health hazards for their beloved fur babies. However, there has been an increasing rise in blue-green algae cases reported that have posed a danger to animals and humans alike. This article will explore the threat of these harmful toxins, including identifying factors, where it can be found, how to recognize the symptoms of algae intoxication, and other information for keeping pets safe and free from harm’s way.

What Is Blue-Green Algae?

Blue-green algae, also known as cyanobacteria, is not actually algae, but a poisonous bacteria that can be found in fresh or salt water when the weather is sunny and warm – over 75 degrees or more. Since the high temperatures promote bacterial growth, these algae intoxications – or more simply put, algae poisoning due to toxic blue-green algae found in affected water bodies – take place primarily during the summer months.

Fresh water that is infested with cyanobacteria can be not only dangerous, but deadly to living creatures – specifically thirsty livestock and pets. This water may look as though it is coated in pea-green paint, or have the appearance of a slimy, floating green film on the surface of the water.

According to Larry Brand, a University of Miami marine biology and ecology professor, cyanobacteria is a primitive algae that evolved around 3.5 billion years ago – and are considered harmful algal blooms (HABs). While infested water can pose a health risk to humans, animals are way more likely to ingest them – humans will note the strange appearance of the water and know not to drink it, but sadly, animals aren’t as fortunate. Additionally, veterinarians have reported that toxic algae has been killing animals for 100 years or more, but according to Brand, it has become increasingly more prevalent across the globe in recent years.

How Does Blue-Green Algae Form?

As a result of the changing environment – specifically global warming and the subsequent rising temperatures of climate change – blue green algae is a growing problem across the world. With temperatures rising worldwide, there are an increasing number of reports of the deadly algae, since it thrives in warm weather. Other research indicates that the usage of crop fertilizer and untreated sewage also promotes cyanobacteria proliferation.

Why Is Cyanobacteria Dangerous?

Blue-green algae (cyanobacteria) contains toxins that can be deadly to dogs within days, minutes or even hours of exposure, so it comes as no surprise that canine owners across the U.S. are very concerned as the cyanobacteria-related fatalities continue to pose a threat. This deadly algae contains microscopic bacteria, and can occur in both fresh and salt water, including streams, freshwater lakes, brackish water, and ponds. The harmful toxins produce include anatoxins and microcystins, which affect humans and animals, including livestock, wildlife, and pets.

Blue-green algae is especially dangerous to canines, since dogs are more likely to romp, play and explore while they’re outside. Since they may have a tendency to drink from open water sources or want to go swimming, dogs are much more vulnerable to algae poisoning than humans. Dogs who enjoy playing fetch outdoors with balls, Frisbees or other toys are particularly at risk – in the event that the park or environment includes some type of water body, all it takes is for your dog to jump into a pond to retrieve a toy and the animal may be exposed to cyanobacteria in mere seconds.

Although not every type of blue-green algal blooms produce toxins, it’s impossible to know if they’re toxic without testing. Therefore, all blooms should be considered potentially toxic – it only takes minimal exposure (such as a dog taking a tiny sip of algae-infested water) for a possibly fatal accident.


Blue-Green Algae & Your Dog: How To Avoid Poisoning

If blue-green algae is present, water ingestion and water intoxication (poisoning) can be fatal to dogs and cats. Additionally, dogs may accumulate the green muck on their fur or paws and lick it off, so pet owners need to be extremely mindful of their surroundings when taking family pets outdoors. If there are any type of water bodies in the surrounding areas, it is of utmost importance to monitor dogs at all times to avoid a potentially deadly outing.

Some tips to include blue-green algae toxicity in dogs include:

  • No drinking environmental water: Never allow dogs to drink out of any natural water source, including lakes, ponds, streams, still water or other similar outdoor water bodies. When spending any time outdoors with pets, be certain to bring fresh bottled water and a collapsible bowl.
  • Keep dogs on a leash: Keep dogs on a leash around water bodies, particularly if the water looks dirty, appears foamy, has a green film on it, or has mats floating on the surface.
  • Keep dogs away from water bodies: While toxic algae blooms may present themselves in a wide array of colors – including bright green, blue, red and brown – sometimes they’re mistaken for paint or another substance floating on the water’s surface, so be wary of anything that looks foreign in the water. In addition, the toxins aren’t always visible, so it’s best to err on the side of caution and prevent dogs from playing in or near any water bodies when outdoors.
  • Curb canine curiosity: According to the EPA, toxic algae typically smells bad – yet curious animals (including dogs) are often attracted to the taste and smell of them. Keep dogs away from bodies of water whenever possible to avoid accidental ingestion or physical exposure to cyanobacteria that may be present.
  • Remain proactive & stay informed: Staying vigilant as a pet parent is key – be sure to keep tabs on parks frequented, as many public health departments will post signs if there is a problem. The most effective form of protection in this case is prevention, precaution, and being aware of the environments that humans and dog spend time in.                                             

Symptoms Of Blue-Green Algae Poisoning In Dogs: What To Look For

Here are some physical symptoms and signs that a dog may display if he has accidentally ingested blue-green algae:

In the event that a dog comes in contact with blue-green algae, be sure to rinse him off immediately with clean, freshwater and take him to the vet right away. Additionally, if a dog displays any of the symptoms as seen above after an outing where water bodies were present, be sure to bring him to the vet’s office promptly for medical attention. 


Sources Cited:

1)      Kalter, Lindsay. “Toxic Algae Kills Dogs Across the Country.”, August 14, 2019, Accessed November 20, 2019.

2)      “Blue-green Algae (Cyanobacteria).” Pet Poison, (no publish date), Accessed November 20, 2019.

3)      Carney, Miranda. “Blue-Green Algae and Dogs: Symptoms and Prevention.” American Kennel, August 13, 2019, Accessed November 20, 2019.

4)  “Pet Safety Alert: The Rising Dangers of Blue-Green Algae.”, August 16, 2019, Accessed November 20, 2019.


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