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Blue-Green Algae: A Lurking Danger to Pets

July 1, 2021

Have you heard of cyanobacteria, and the danger it poses to dogs? Also known as blue-green algae, cyanobacteria is an extremely dangerous algae that typically lives in warm, nutrient-rich water. It can make both people and pets very sick. Blue-green algae grows rapidly, or bloom, under the right conditions. Unfortunately, these blooms are becoming much more common. A veterinarian discusses cyanobacteria below. 

Warning Signs

Usually, blue-green algae blooms happen in summer and early fall. However, they can happen anytime the water temperature goes over 75°F. Many local authorities and newscasts will alert people when a body of water has been contaminated, and some will close lakes or post signs. However, it can be easy to miss these updates. The EPA has a map here with cyanobacteria resources for every state. We recommend double checking before taking Fido swimming.


As mentioned above, blue-green algae is extremely dangerous. You don’t even 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, or even just wading. Cyanobacteria can also stick to pets’ fur, where they can later lick it off.


Blue-green algae looks like pea soup or green paint. It can also cause a swampy, musty odor. You may not see or smell smaller blooms, but they are still very dangerous. It’s also worth noting that, while not all algae blooms are harmful, 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!


Blue-green algae can make any pet sick, but our canine pals 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, and can be fatal. Warning signs include panting, dizziness/disorientation, respiratory problems, diarrhea, vomiting, seizures, and excessive drooling. If your pup shows any of these warning signs, treat it like a medical emergency and call your veterinarian immediately.


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

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