Lake Oswego veterinarian, Dr. Gregg Takashima, wants pet owners to know the warning signs of blue green algae toxicity. Summer is when the bacteria shows up as a scummy, blue-green sheen on area ponds, lakes and rivers.  It can kill a dog that ingests it through drinking the water, or even swimming through it.  Dr. Takashima says if your dog has been in water somewhere and exhibits those symptoms, get immediate vet care.