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Blue-Green Algae: A Lurking Danger to Pets

June 15, 2021

Have you heard of cyanobacteria blooms? You may know cyanobacteria by its common name: blue-green algae. Cyanobacteria is an extremely dangerous algae that typically lives in warm, shallow, water, which tends to be rich in nutrients. It can make both people and pets very sick. It can grow rapidly, or bloom, under the right conditions. Unfortunately, these blooms are becoming much more common. A local veterinarian discusses cyanobacteria below.


Blue-green algae often looks like pea soup or green paint. It can also cause a stinky, swampy odor. However, you can’t judge a lake by its cover. Smaller blooms can still be dangerous, even though they may not alter the look (or smell) of a lake or pond very much. It’s also worth noting that not all algae blooms are harmful. However, you can’t tell by looking at a lake whether it is or isn’t safe. Err on the side of caution here: if in doubt, just stay out!

Warning Signs

Blue-green algae blooms usually occur in summer and early fall. This is when we usually see them in the Great Lakes. However, blooms can happen whenever the water temperature goes over 75°F. Local authorities and newscasts often alert people when a body of water has been contaminated, and some will even post signs. However, it can be easy to miss these updates. This is definitely something you want to look into before taking Fido swimming!


As mentioned above, blue-green algae is extremely toxic. You don’t have to drink contaminated water to get sick: you can also become ill through skin contact or by breathing in water droplets or vapors. This can happen when swimming, boating, or tubing. Cyanobacteria can also stick to pets’ fur, where they can later lick it off.


Blue-green algae can make any animal sick, but Fido is particularly at risk, as he loves to swim or splash around in water. Blue-green algae can cause very serious neurological problems and/or liver failure. Sadly, it can be fatal. Warning signs to look for include panting, respiratory problems, vomiting, diarrhea, dizziness/disorientation, seizures, and excessive drooling. If your canine buddy shows any of these things, call your veterinarian immediately.


As always, an ounce of prevention is worth more than a pound of cure. Be very careful when choosing Fido’s swimming holes! Also, don’t let your pup drink from lakes or ponds, especially ones with blue-green scum.

Do you have questions about pet care? Contact us, your animal clinic in Carlisle, ON, today!

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