Dog owners warned to avoid certain Swiss lakes after 3 poisonings

Dog owners in Switzerland are being reminded not to walk their pets near lakes where blue-green algae are blooming, after one dog died and several others were poisoned through suspected contact with contaminated water in Glarus. 

One dog dies in Glarus after suspected blue-green algae poisoning

A small vet practice wrote on Facebook last weekend that it had seen three owners who had brought in dogs with suspected cases of poisoning after visiting Lake Obersee Näfels in Glarus. They said they presumed the dogs had been poisoned by blue-green algae in the lake. 

“Two dogs were brought to my practice. Unfortunately, one died before arriving here. One came in with symptoms of poisoning,” the vet told 20 Minuten. A third dog was taken to another veterinary practice for treatment. The vet took to Facebook to warn people against letting their dogs go into the lake - and by extension any Swiss lake known to have a blue-green algae infestation.

Although it’s very difficult to prove that blue-green algae was the cause of the poisoning, the lake has been known to be affected by the toxic algae for years. The municipality confirmed to 20 Minuten that it was aware of the problem and had placed prominent signs around the lake to warn walkers about the danger of entering the lake. 

What is blue-green algae and why is it dangerous to dogs?

The deceptively-named blue-green algae is actually a kind of bacteria that is present in most bodies of water and is usually unproblematic. It only causes issues when it starts to multiply quickly, as it does during prolonged periods of fine weather: it loves high temperatures and sunshine. Some kinds of blue-green algae then produce toxins that can be dangerous for dogs and small children. 

Dogs often die from bathing in or drinking water that contains blue-green algae. They are at particularly high risk of poisoning, according to Beobachter, as they not only drink the water, but also can consume it when licking their fur or paws. Poisoning doesn’t typically occur through skin contact. 

Symptoms of blue-green algae poisoning include increased salivation, vomiting and diarrhoea. In severe cases, it can lead to twitching, cramps, shortness of breath, loss of consciousness and paralysis. 

To protect both humans and animals, most Swiss cantons provide information on where there is currently an excessive concentration of blue-green algae. You can recognise an infestation from the algae’s distinct green colour, which forms a kind of greasy coating on the water surface and often coats stones along the shoreline.