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Blue-Green Algae

Blue-green algae has been in the news a lot lately, and the alerts and testimonials coming out are sad and scary for those of us with water-loving pets. So let’s learn a bit more about this blue-green algae.

Blue-green algae is not actually an algae, but a species of bacteria called cyanobacteria that is a normal resident of many lakes. These bacteria grow best in warm, very nutrient-rich water – conditions that are very common in late summer. Under ideal conditions they can suddenly reproduce very quickly in massive numbers, which are called “blooms.”

Cyanobacteria produce a group of toxins called cyanotoxins. Cyanotoxins include neurotoxins (toxins that target the nervous system), hepatotoxins (toxins that target the liver), and dermatoxins (toxins that target the skin). When populations of cyanobacteria are low or normal, theses toxins are present in such small amounts in the water that they are not dangerous. However, during a bloom the high populations of bacteria produce huge amounts of these toxins. Pets (and people!) can be exposed to these high levels of toxins not only by ingesting water (often during swimming) but by contact with the skin or inhaling water droplets during any water activity that causes splashes (waterskiing, dock diving). In particular, a neurotoxin called anatoxin-a (also called “very fast death factor”!!) can cause death extremely rapidly by blocking nerve signals that control essential functions such as breathing.

Because cyanotoxins can be lethal so quickly, the best advice is to stay out of the water when blooms are present. It can be difficult to tell for sure when a bloom is happening. News outlets, the Department of Health, and Minnesota Pollution Control Agency do release alerts when blooms are identified in specific lakes, so keep an eye on the news. Blooms are sometimes described as looking like pea soup or someone spilled green paint or dye in the water. Click here for examples of blue-green algae blooms.


The Minnesota Pollution Control Agency also has a good link here with some simple tests you can do to check for an algae bloom. These are most useful for lakes where you have a home or cabin, as you need some simple equipment and time to perform them. They are less likely when you run out for an afternoon with your dog and are trying to decide if the water in front of you right now is safe.

So the bottom line is, if you’re not sure then keep your pet out of the water and do not use lake water for cooking, washing, brushing teeth, etc when camping (and note that boiling water does NOT break down the toxins and may in fact concentrate them as some of the water evaporates during boiling). We want our water-loving patients (and their owners!) to stay safe out there!

Karen Christopherson DVM CVA