Duckweed and Blue-Green Algae Pose Dangers To Your Lake-Loving Dog

Mary Simpson
by Mary Simpson

Recent death of healthy dogs have pet parents being uber-diligent around lakes, ponds, and streams.

(photo credit: Pokoman / shutterstock.com)

Summer’s here, and with camping, hiking, picnicking and trips to the cottage, there isn’t a pooch around (except maybe mine) who doesn’t want to jump to the lake, pond, or river to cool off. Especially for water dogs such as, well, every variation of retriever and spaniel, the draw to water and the love of swimming is, quite frankly, innate.


But here’s the thing. Regardless of how strong a swimmer your dog may be, no matter how badly he needs a quick dip to escape the summer’s heat, or how carefully you’re monitoring his activities, there are a couple of dangers you will almost certainly have not anticipated.


Let’s start with Duckweed (AKA Watermeal, Lemna minor, Spirodela polyriza, Wolffia columbiana). Just like it sounds, it’s a weed that thrives in still, nutrient-rich water. Yes, this includes lakes, marshes, ponds and slow-running streams – all the places where we’re likely to let our pooch dive right in without a second thought. Now, this particular water weed has a small, clover-like leaf, and when conditions are right (heat and moisture), it rapidly clones and can literally create a carpet across the water’s surface. Great for frogs and bugs who like to rest atop it, but not so great for the ecosystem as the solid mass blocks the light from everything that’s trying to grow beneath the surface.


Nor is it great for dogs who shore dive into the mass. That’s because the hardy, mesh-like composition can trap – and in some instances even drown - dogs who can’t pull themselves out of the heavy web. And while you may not be familiar with this particular weed, there are nine species of Duckweed that have been reported across Canada and in all states except Hawaii and South Carolina. So, it’s out there.


The second challenge to water-loving dogs is something called cyanobacteria, which has already infected five dogs in British Columbia, three of which have died. How were they exposed to such a deadly toxin? By simply jumping into a local lake for a paddle. You see, the bacteria present as simple blue-green algae that one might mistake as a natural phenomenon – something we’ve all seen on lakes whenever heat waves occur. However, this thick layer of surface algae is actually laced with a potent liver toxin that, if ingested as he swims, can cause your pet to experience vomiting, seizures, organ failure, and even death. It can also sicken humans via rashes and respiratory issues.


While water testing was being conducted at the British Columbia lake, it was not to the level it needed to be, with the family of one of the lost dogs demanding higher-grade tests that include full toxin panels. It’s suspected that runoff from cattle operations and shoreline fertilization may have led to contamination of this particular watershed, which, with the heat, contributed to the algae growth.


These instances are not to discourage pet owners from enjoying the great outdoors and waterways with their pets. Just be diligent. Tips for keeping your pet safe when swimming include a quick scan of the water surface condition to ensure it’s free of weeds and algae before Rover jumps in. And always use a flotation vest on any dog who isn’t a strong swimmer. Because exhaustion can also compromise our pet’s safety and that’s not how we want to remember our summers.

Mary Simpson
Mary Simpson

Sharing space with three seriously judgy Schnoodles and 2 felines who prefers to be left alone. #LivingMyBestLife

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