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Blue-Green Algae: A Deadly Danger for Dogs

Does your local pond have this common, deadly algae?

Posted August 06, 2014 in Dog Toxins & Poisons

Pond with Blue-Green Algae

Before you let your dog jump into that lake to cool off this summer, pay heed! As the dog days of summer sadly come to an end, I wanted to write to warn you to be more discriminating about what lakes you let your dog swim in this summer and fall.

Maybe I’m just a bit paranoid, but when it comes to swimming in lakes, you want to make sure to avoid ones that have that green-scum layer on top of the lake. Why? It’s because during really hot summers and the fall, there’s an increased likelihood of the lake developing a thick “bloom” of algae that floats on the surface. So, why do I worry about algae as a toxicologist? I worry because of blue-green algae.

What is blue-green algae?
Blue-green algae, which is also called cyanobacteria, is a microscopic bacteria found in freshwater ponds, lakes, streams, and brackish water ecosystems. Note that not all types of algae are poisonous, but some types (e.g., blue-green) can produce toxins called microcystins and anatoxins. These toxins are so dangerous that they are actually poisonous to other species too: humans, cattle, horses, cats, etc. For this reason, you shouldn’t allow your dog (or child) to swim or drink water that has been potentially contaminated with blue-green algae.

Symptoms of blue-green algae poisoning
Clinical signs of blue-green algae poisoning depend on what type of toxin (e.g., microcystin vs. anatoxin) is present. Clinical signs of blue-green algae that produce microcystins, typically include:

  • Malaise/lethargy
  • Weakness
  • Not eating
  • Vomiting
  • Diarrhea
  • Black-tarry stool
  • Collapse
  • Pale gums
  • Jaundice (yellow) gums
  • Shock
  • Seizures
  • Death

With blue-green algae that produce anatoxins, symptoms include:

  • Inability to walk
  • Hypersalivating
  • Excessive (eye) tearing
  • Tremors
  • Muscle rigidity
  • Difficulty breathing or blue gums
  • Death

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Justine has more than 18 years of experience in the veterinary industry and is a board-certified emergency critical care veterinary specialist and toxicologist as well as the CEO and founder of Vetgirl. She is also a founding member of IDEXX’s Pet Health Network team.