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Blue-Green Algae: A Lurking Danger to Pets

June 15, 2021

Have you heard of cyanobacteria? You might know it by its common name: blue-green algae. This is a very dangerous algae that typically thrives in warm, nutrient-rich water. Cyanobacteria can make both people and pets extremely sick, and can even be fatal. It can grow rapidly, or bloom, under the right conditions. Unfortunately, these blooms are becoming much more common. A veterinarian discusses cyanobacteria below.

Warning Signs

Blue-green algae blooms most often happen in summer and early fall. There is a risk of blooms anytime the water temperature goes over 75°F. Local authorities and newscasts often alert people when a body of water has been contaminated, and some post signs. However, if you’re not paying close attention, it can be easy to miss these updates. This is definitely something you want to check before taking Fido swimming!


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


As mentioned above, blue-green algae is highly toxic. You don’t have to drink contaminated water to get sick: you can also absorb the algae through skin contact or even by breathing in water droplets or vapors. This often happens when people (or dogs) go swimming, boating, or tubing in blooming lakes. Cyanobacteria can also stick to pets’ fur, where they can later lick it off.


Blue-green algae can make any animal sick. Unfortunately, they often kill wild animals. As for pets, dogs are particularly at risk, especially those that love to swim or splash around in water. Blue-green algae can cause very serious neurological problems and/or liver failure. Ingestion can be fatal. Warning signs include panting, respiratory problems, vomiting, diarrhea, dizziness/disorientation, seizures, and excessive drooling. The effects of blue-green algae come on very suddenly, and are potentially life-threatening for Fido. If your pet shows any of these warning signs, call your veterinarian immediately. 


A s always, prevention is worth much more than cure. Be careful when choosing Fido’s swimming holes. Don’t let your pooch drink from lakes or ponds, especially ones with blue-green scum! 

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

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