Dangerous bathing fun - blue-green algae poisoning in dogs

hund steht in einem fluss hund steht in einem fluss


In hot months, many two-legged and four-legged friends take to the water to cool down.A small stream, a nearby lake, a pond around the corner, all seem ideal for a little refreshment -- if it weren't for blue-green algae. If the water is contaminated, your happy outing can end badly. 

What is blue-green algae? 

Blue-green algae is actually bacteria, which is scientifically called cyanobacteria. Some species produce a blue pigment, hence the ‘blue’ in its name. Mostly, however, they look greenish-blackish, sometimes even reddish. It is among the oldest organisms on the planet and supplies living creatures in the water with oxygen, which it produces itself. In this sense, blue-green algae is in itself an important part of the eco-system. 

The danger occurs when something known as algal bloom forms.This can occur when the water regularly reaches a temperature of 25 degrees or more. So it is most likely to happen in the summer months. In addition, contamination by sewage can also lead to an explosive spread of blue-green algae. Any body of water can be affected. Although the likelihood of algal bloom is somewhat higher in stagnant freshwater, bacteria can also become rampant in a flowing stream or in salt water.

Toxic for dogs and humans  

Some of these bacterial species produce toxins. They are visually indistinguishable from the non-toxic species. Therefore, utmost caution is always advised if contamination with blue-green algae is suspected. This applies to humans and animals. 
In dogs, the toxin enters the body through the mouth when they swallow the toxic water or lick it off their fur. The toxin travels through the bile duct system until it reaches the liver, where it attack the cells. It can also lead to kidney damage, clotting disorders and several neurological symptoms. In the worst case, blue-green algae poisoning can lead to death.

hund trinkt wasser aus einem teich hund trinkt wasser aus einem teich

Possible signs of blue-green algae in the water 

  • The water is murky and bluish-green
  • Green-blackish coatings are found on stones at the edge of the bank
  • A greenish, streaky algae carpet floats on the water surface or a little below it
  • You can see less than 1 metre into the depths
  • You wade knee-deep into the water without stirring up mud and yet you can no longer see your feet
  • At times the water smells of rotten eggs, manure and ammonia

Preventing poisoning 

Of course, it is best if neither you nor your furry friend come into direct contact with the toxic bacteria. Some official bodies provide information on current bathing water quality. In Austria, the Agency for Health and Food Safety (AGES) carries out constant measurements, while Germany has authorities specific to each federal state to do so. The reports are usually available online. In addition, you can ask in your local municipality if there is any information on the current situation. Should there ever be an official bathing ban, be sure to comply with it! 

Since samples are not taken from every single body of water, avoid places that tend to promote the growth of blue-green algae if possible. Take a water bottle with you on every walk so that your dog does not necessarily have to drink water from warm puddles. After swimming in lakes or playing in streams, thoroughly showering with lukewarm, clear water at home is generally a good idea to rinse any potential bacteria residues from their fur. 


Possible symptoms of blue-green algae poisoning

  • increased salivation
  • frantic panting
  • shortness of breath
  • vomiting
  • diarrhoea
  • disorientation
  • weakness, unconsciousness
  • skin rash, itching
  • pale or bluish mucous membranes in the mouth
  • muscle tremor, muscle cramps
  • paralysis

Symptoms usually appear within a short time after contact with the bacteria. If you suspect blue-green algae poisoning in your dog, please seek veterinary help as soon as possible.
If your pet has only caught a small dose of blue-green algae, individual symptoms such as vomiting or diarrhoea may not be immediately associated with the last swimming trip. Inform your vet about recent activities so that the possibility of blue-green algae poisoning can be checked. 

Additional tips from the clinic

Some veterinary clinics recommend having activated charcoal handy as a first aid measure. Discuss this at your clinic and ask about the recommended dose for your furry friend. 
It is always best to bring the dog to the water on a leash and first make sure that it really is safe to go in. If not, you can always offer a treat as a consolation and the promise to come back when you can splash around without worrying.