Blue Green Algae Is Poisonous To Dogs

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