Organisms, cyanobacteria, known as blue-green algae, can be found in freshwater lakes, streams, ponds, estuaries, hot springs and water from wastewater treatment plants. Concentrations of these organisms can be found at any time but are almost always associated with hot weather and nutrient-rich water. Most blue-green algae blooms are not toxic but sometimes they produce microcystins and/or anatoxins that can kill birds, wild animals, aquatic animals, livestock, people or pets that ingest contaminated water. Unfortunately it is not possible to know if toxins are present when the characteristic “pea soup” scum is present without testing for them. If anatoxins are present a few mouthfuls of contaminated water can be fatal. Dogs that swim in such water and lick themselves when they come out have been poisoned.
Signs of poisoning by microcystins are vomiting, diarrhea, bloody stools, weakness, pale mucous membranes, jaundice, seizures, disorientation, coma, shock and death from liver failure, usually within days. The diagnosis is based upon the history of exposure to the algae and blood work indicating elevated liver enzymes, low blood sugar, low protein and sometimes abnormal clotting.
The anatoxins produce neurotoxicity with signs of muscle tremors, muscle rigidity, and paralysis, along with dyspnea, difficult breathing, and signs of low blood oxygenation. Death can occur very quickly, minutes to hours after exposure, usually from respiratory muscle paralysis.
An article published by George Francis in the journal NATURE in 1878 described animals dying rapidly after drinking water from the Murray River estuary that contained “a thick scum like green oil paint”.
There is no known antidote for these toxins. Immediate supportive treatment, based upon the signs the animal is showing, by your veterinarian is imperative.